Citation
Water control in the peat and muck soils of the Florida Everglades

Material Information

Title:
Water control in the peat and muck soils of the Florida Everglades
Series Title:
Bulletin - University of Florida Agricultural Experiment Station ; 378
Creator:
Clayton, B. S.
Neller, J. R.
Allison, R. V.
Place of Publication:
Gainesville, Fla.
Publisher:
University of Florida Agricultural Experiment Station
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
The Everglades ( local )
Lake Okeechobee ( local )
Soil science ( jstor )
Water tables ( jstor )
Pumps ( jstor )

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
The University of Florida George A. Smathers Libraries respect the intellectual property rights of others and do not claim any copyright interest in this item. This item may be protected by copyright but is made available here under a claim of fair use (17 U.S.C. §107) for non-profit research and educational purposes. Users of this work have responsibility for determining copyright status prior to reusing, publishing or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder. The Smathers Libraries would like to learn more about this item and invite individuals or organizations to contact Digital Services (UFDC@uflib.ufl.edu) with any additional information they can provide.

Downloads

This item has the following downloads:


Full Text



Bulletin 378


November, 1942


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
WILMON NEWELL, Director GAINESVILLE, FLORIDA


Cooperating with
UNITED STATES DEPARTMENT OF AGRICULTURE
SOIL CONSERVATION SERVICE
H. H. BENNETT, Chief







WATER CONTROL IN THE

PEAT AND MUCK SOILS

OF THE FLORIDA EVERGLADES


By


B. S. CLAYTON, J. R. SELLER and R. V. ALLISON


Single copies free to Florida residents upon request to
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA






EXECUTIVE STAFF
John J. Tigert, M.A., LL.D., President of the University'
Wilmon Newell, D.Sc., Director' Harold Mowry, M.S.A., Asso. Director L. 0. Gratz, Ph.D., Asst. Dir., Research W. M. Fifield, M.S., Asst. Dir., Admin.4 J. Francis Cooper, M.S.A., Editor' Clyde Beale, A.B.J., Assistant Editor3 Jefferson Thomas, Assistant Editor' Ida Keeling Cresap, Librarian Ruby Newhall, Administrative Manager' K. H. Graham, Business Manager' Claranelle Alderman, Accountants

MAIN STATION, GAINESVILLE
AGRONOMY
W. E. Stokes, M.S., Agronomist' W. A. Leukel, Ph.D., Agronomist" Fred H. Hull, Ph.D., Agronomist G. E. Ritchey, M.S., Associate' W. A. Carver, Ph.D., Associate Roy E. Blaser, M.S., Associate G. B. Killinger, Ph.D., Associate Fred A. Clark, B.S.A., Assistant
ANIMAL INDUSTRY
A. L. Shealy, D.V.M., An. Industrialist' a R. B. Becker, Ph.D., Dairy Husbandmans E. L. Fouts, Ph.D., Dairy Technologists D. A. Sanders, D.V.M., Veterinarian M. W. Emmel, D.V.M., Veterinarian' L. E. Swanson, D.V.M., Parasitologist' N. R. Mehrhof, M.Agr., Poultry Hush.3 T. R. Freeman, Ph.D., Asso. in Dairy Mfg. R. S. Glasscock, Ph.D., Asso. An. Hush. D. J. Smith, B.S.A., Asst. An. Husb.' P. T. Dix Arnold, M.S.A., Asst. Dairy Husb.' G, K. Davis, Ph.D., Tech. in An. Nutrition L. E. Mull, M.S., Asst. in Dairy Tech.' 0. K. Moore, M.S., Asst. Poultry Hush. C. B. Reeves, B.S., Asst. Dairy Tech. J. E. Pace, B.S., Asst. An. Hush.
ECONOMICS, AGRICULTURAL C. V. Noble, Ph.D., Agr. Economist' :1 Zach Savage, M.S.A., Associate A. H. Spurlock, M.S.A., Associate Max E. Brunk, M.S., Assistant
ECONOMICS, HOME Ouida D. Abbott, Ph.D., Home Econ.' Ruth 0. Townsend, R.N., Assistant R. B. French, Ph.D., Asso. Chemist
ENTOMOLOGY
J. R. Watson, A.M., Entomologist A. N. Tissot, Ph.D., Associate H. E. Bratley, M.S.A., Assistant
HORTICULTURE
G. H. Blackmon, M.S.A., Horticulturist' A. L. Stahl, Ph.D., Associate F. S. Jamison, Ph.D., Truck Hort. R. J. Wilmot, M.S.A., Asst. Hort. R. D. Dickey, M.S.A., Asst. Hort. J. Carlton Cain, B.S.A., Asst. Hort.' Victor F. Nettles, M.S.A. Asst. Hort.' Byron E. Janes, Ph.D., Asst. Iort. F. S. Lagassee, Ph.D., Asso. Hort.2 H. M. Sell, Ph.D., Asso. Hort.'
PLANT PATHOLOGY
W. B. Tisdale, Ph.D., Plant Pathologist' George F. Weber, Ph.D. Plant Path.3 Phares Decker, Ph.D., Asso. Plant Pathologist Erdman West, M.S., Mycologist Lillian E. Arnold, M.S., Asst. Botanist
SOILS
R. V. Allison, Ph.D., Chemist' Gaylord M. Volk, M.S., Chemist F. B. Smith, Ph.D., Microbiologist' C. E. Bell, Ph.D., Associate Chemist J. Russell Henderson, M.S.A., Associates L. H. Rogers, Ph.D., Asso. Biochemist' Richard A. Carrigan, B.S., Asso. Chemist4 L. E. Ensminger, Ph.D., Asso. Soils Chew. H. W. Winsor, B.S.A., Assistant Chemist Geo. D. Thornton, M.S., Asst. Chemist R. E. Caldwell, M.S.A., Soil Surveyor Olaf C. Olson, BS., Soil Surveyor


BOARD OF CONTROL
H. P. Adair, Chairman, Jacksonville R. H. Gore. Fort Lauderdale N. B. Jordan, Quincy T. T. Scott, Live Oak Thos. W. Bryant, Lakeland J. T. Diamond Secretary, Tallahassee

BRANCH STATIONS
NORTH FLORIDA STATION, QUINCY J. D. Warner, M.S., Agronomist in Charge R. R. Kincaid, Ph.D., Asso. Plant Pathologist R. W. Wallace, B.S., Asso, Agronomist J. H1. Wallance, M.A., Asso. Agronomist Elliott WhiLehurst, B.S.A. Asst. An. Husb.' W . C. McCormick, B.S.A., Asst. An. flush. Jesse Reeves, Asst. Agron., Tobacco W. H. Chapman, M.S., Asst. Agron.4
CITRUS STATION, LAKE ALFRED A. F. Camp, Ph.D., Horticulturist in Charge V. C. Jamison, Ph.D., Soils Chemist B. R. Fudge, Ph.D., Associate Chemist W. L. Thompson. B.S., Associate Ento. F. F. Cowart. Ph.D., Asso. Horticulturist W. W. Lawless, B.S., Asst. Horticulturist' R. K. Voorhees, Ph.D., Asso. Plant Path, H. 0. Sterling, B.S., Asst. Hort. T. W. Young, Ph.D., Asso. Hort., Coastal C. R. Stearns, Jr., B.S.A., Chemist
EVERGLADES STA. BELLE GLADE J. R. Neller, Ph.D., Biochemist in Charge J. W. Wilson, Sc.D., Entomologist F. D. Stevens, B.S., Sugarcane Agron. Thomas Bregger, Ph.D., Sugarcane Physiologist
G. R. Townsend, Ph.D., Plant Pathologist R. W. Kidder, M.S., Asst. An. Hush. W. T. Forsee, Ph.D., Asso. Chemist B. S. Clayton, B.S.C.E., Drainage Eng.' F. S. Andrews, Ph.D., Asso. Truck Hort.' Roy A. Bair, Ph.D., Asst. Avron. E. C. Minnurn, M.S., Asst. Truck Hort.
SUB-TROPICAL STA., HOMESTEAD Geo. D. Ruehle, Ph.D. Plant Path. in Charge S. J. Lynch, B.S.A., Asst. Horticulturist E. M. Andersen, Ph.D., Asst. Hort.
W. CENT, FLA. STA., BROOKSVILLE W. F. Ward, M.S., Asst. An. Hush. in Charge2
RANGE CATTLE STA. ONA W. G. Kirk, Ph.D., An. Hush. in Charge E. M. Hodges, Ph.D., Asso. Agron., Wauchula Gilbert A. Tucker, B.S.A., Asst. An. Husb.4 Floyd Eubanks, B.S.A., Asst. An. Hush.
FIELD STATIONS
Leesburg
M. N. Walker, Ph.D., Plant Path. in Charge4 K. W. Loucks, M.S. Asst. Plant Path. E. E. Hartwig Ph.D., Asst. Agron. & Path.
Plant City
A. N. Brooks, Ph.D., Plant Pathologist
Hastings
A. H. Eddins, Ph.D., Plant Pathologist E. N. McCubbin, Ph.D., Asso. Truck Hort.
Monticello
S. 0. Hill, B.S., Entomologist2 A. M. Phillips, B.S., Asst. Entomologist'
Bradenton
Jos. R. Beckenbach. Ph.D., Truck Hart. in Charge
E. G. Kelsheimer, Ph.D., Entomologist F. T. McLean, Ph.D. Horticulturist A. L. Harrison, Ph.D., Asso. Plant Path. David G. Kelbert. Asst. Plant Pathologist
Sanford
R. W. Ruprecht, Ph.D., Chemist in Charge, Celery Investigations Jack Russell, M.S., Asst. Entomologist
Lakeland
E. S. Ellison, Meteorologist' Harry Armstrong, Asso. Meteorologist' ' Head of Department. In cooperation with U. S.
' Cooperative, other divisions, U. of F.
'On leave.















CONTENTS


PAGE
-------------- 5

------- - ---------- 8

--- --- ------ --- --- 1 0

------------ --------- 15

--------------- ------ 17

- . . - 20 . 20 . 27

. . 35 - -1 ------ ---- 38

---- - -- -- ------ 3 9

----- . -- ---- 4 7

- --- -- ------ 56

-_ - -------- ---- 60

--- ---- ----------- 6 0

. . 62

---- 62

------ 70

------- ------- 7 1

------- ----------- 71

- ----- ------- . 71

------------ 72

---------- ------ --- 7 2

. . . --- 72

- ---- ----- I --- 73

__ --- . . - 73


THE EVERGLADES PRO13LE-M . . _ - - . - _DESCRIPTION OF THE EVERGLADES AREA SOILS OF THE EVERGLADES SUBSIDENCE OF PEAT SOILS ---- -- - ----SEEPAGE THROUGH PEAT SOILS . ---------- --- ------CLIMATOLOGICAL DATA ----------------_------- ----- ------R ain fall ------------- - ------------------------ ----- - - -----Evaporation and Transpiration - -- ---- -T em perature .-. . ----- ---------- --WATER CONTROL BY PUMPING ------- - --- . -Description of Pumping Plants . . . _.

Fixed and Operating Costs of Pumping

Efficiency Tests on Pumping Plants . .

F arm D itches . . ---- ---- ---- - -----M ole D rainage . ------ ----- - --------- -- --- --- ---WATER TABLE STUDIES -. - ------ . . . .

The Well Lines ----- . ___ _ ---------Water Table Plots --- ----- ------ .-- -S U M M A RY -------------------------------- -------------------- ---------

S o ils ---------------------- ------- -- ------ --------- - -- ------- -S ub siden ce -------------- -------------- --- ------------ -------S eep a ge . . _' ----------- ----- ----------- ---Rainfall, Evaporation and Temperature

Water Control by Pumping .- . . -.

Ditches and Sub-Drainage ---- --- -

Water Table Studies . . .






FOREWORD
The reclamation and agricultural utilization of the organic soils of the Everglades has created a problem of soil conservation that is vital to the f uture of this area.
The conservation of organic soils tinder cultivation is no less difficult than it is important. Neither is it unique to the soils of the Everglades, since the record of reclamation activities on soils of this type in other states and in other countries of the world shows a practically complete disintegration and destruction of the soil body, almost without exception, under conditions of continued use-and abuse.
Everglades soPs require protection against natural oxidation as well as actual burning, and the consequent surface subsidence which occurs under almost any condition of reclamation.
We must try to learn all there is to be known about the handling of the natural waters of this tremendous flatland area that we may use them in such a way as to protect and conserve the soils under reclaimed as well as unclaimed conditions, just as fully as possible. Such an objective is neither drainage nor irrigation, but WATER CONTROL in the fullest sense of the word.
The program towards which such an ideal approach points must be broad enough to include the hydrology of the entire Everglades system, that is, the Kissimmee watershed and related watersheds, Lake Okeechobee, and the original overflow area which is the Everglades itself. Such a plan also must take cognizance of the eccentricities of the climate from year to year. Also it must give most careful consideration to the development of adequate water reserves to meet not only ever-increasing demands for domestic water supplies, municipal and other, and the growing requirements of agriculture as the reclaimed area steadily expands, but also the equally specific needs for soil conservation under unreclaimed conditions. Fortunately the several requirements of the plan do not conflict but can be developed in full harnmoy with each other, provided the question of water supply is held paramount and there is no serious shortage at any time.
In attacking a problem of this breadth we are, of course, exceedingly grateful for the interest and support of such an organization as the Soil Conservation Service of the U. S. Department of Agriculture. The Chief of this Service, Dr. H. H. Bennett, has had a deep technical interest in the problems of the Everglades for a great many years, as has also Mr. L. A. Jones, Chief of the Drainage Division in the Research Branch of the Service with whose office the cooperation in this phase of the work has been maintained. The results reported in this bulletin relate very closely, of course, to the operation and demonstration project initiated by the Service in 1939 with headquarters in Ft. Lauderdale. This part of the Service's program in the Everglades is under the management of Mr. C. Kay Davis, to whom we are also very much indebted for the steady interest and cooperation of his whole staff during the past three years.
HAROLD MOWRY








WATER CONTROL IN THE PEAT AND MUCK SOILS
OF THE FLORIDA EVERGLADES
By B. S. CLAYTON,' J. R. SELLER and R. V. ALLISON

In the spring of 1932 a cooperative agreement was entered into by the Agricultural Experiment Station of the University of Florida and the Bureau of Agricultural Engineering of the United States Department of Agriculture for the purpose of investigating problems relating to water control in Florida2 peat soils. Headquarters for the work was established at the Everglades Experiment Station near Belle Glade. The work has continued since that time.
Early efforts at water control were confined to a system of gravity ditches. Due to soil subsidence and the flat topography of the land this method proved inadequate and pumps, installed later, now serve nearly all the cultivated land.
All elevations used in this report are based on the old Punta Rassa datum which has been generally used by drainage districts in the northern Everglades. This datum is approximately 1.4 feet below the mean sea level datum of the United States Coast and Geodetic Survey. Hence to reduce the elevations used to mean sea level 1.4 feet should be subtracted from the figures given.
Figure 1 is a map of the northern Everglades showing some of the larger drainage canals and pumping plants.

THE EVERGLADES PROBLEM
The outstanding problem of the Florida Everglades is concerned with prolonging the useful life of the cultivated land and conserving the virgin lands from the destructive effects of subsidence and fires. A successful solution of this problem would benefit the cities of the lower East Coast, since these depend largely on shallow wells for their water supply. Insofar as a higher water table can be maintained in the Glades a larger yield of salt-free water can be obtained from these wells. It is also believed that a higher water table would reduce the frost hazards in the cultivated lands.
Associate drainage engineer, Soil Conservation Service, U. S. Department of Agriculture, and drainage engineer, Everglades Experiment Station.
" Following a reorganization of the Department, effective July 1, 1939, the cooperation has been continued between the Soil Conservation Service and the Experiment Station.






Florida Agricultural Exiperiment Station


I-AKE OKEECHTOBEE Q R
CanalPon

MAoore Haven 7
PahokeeClwito I -------- -----------and well ines inate Hkeecob ra

of--------- the ---- Evr -ae to-- their orgiacnitohihisnwm
practicable. ~ ~ ~ ~ ~ ~ E_ Hoevr ifteaaial aeri oditiue
thata hiherwate tabei manaie th lose from subsi
denc an firs cn bemuc redced

The sefu lif of he cltivted andscan e inreaedb
mantinngth hghstwaertalecopaIles wihgodco
yields. A water table depthof . o . ee rduehebs
yiel fo mos crps nw gown n te Evrgldes





would reul inE a,3 hihe wae tablE. The 7 lan oeihrside



of the NorhaNew Rivter Cagnal aotton fetwr thn that seralicles backv, ls the wateritable, dutrig dry wethrie muh lowiger near tcal thmaaniseea mies lout.s Aso fasubi

posblThe fe flo of theslied ans shoul be iresed by





Wate?- Control in the Soils of the Everglades


dams which should remain closed at all times except during extreme high water.
If these canals were held at near bank f ull stage the total amount of pumping would be increased due to seepage into the diked areas, but as pumping costs are low this increase would not greatly change the cost of operation of pumping districts.
A system of dikes has been proposed as a means of holding rainfall on the idle lands. There is some doubt as to whether the increased height of the water table during the spring months would be sufficient to justify the costs. Also, it would be difficult to protect these dikes from fires. However, the possibility of retaining water by dikes should be examined. Several typical areas should be completely enclosed and the results observed before expanding the system.
The discharge from Lake Okeechobee through its two outlets averages about 11/1 million acre-feet per year, but due to the elevation of the land outside the levee it would be very difficult to spread this water over the virgin lands. However, some of this water could be used to maintain a high level in the large canals during the dry season, and thus decrease the subsidence losses.
Under present conditions the cultivated acreage in the Glades is being expanded without any general plan. This is leading to a condition where much of the land back from the existing roads will have no outlet. Under this condition it is impossible to design outlet canals with any certainty as to the drainage areas which they should serve. This unfortunate situation will become worse unless some general plan of development is adopted.
After a field survey is completed of the agricultural land a map should be prepared and a system of levees and canals projected which would provide outlets for all agricultural land. These levees and canals could be constructed as need arises for new land, but would conform with the general plan adopted. All new land should then come in as sub-districts with pumps placed so as to discharge at points provided in the general plan.
It might prove feasible to provide north and south outlet ditches along range lines and require sub-districts to extend back three miles. Those interested in forming a new sub-district should first prepare a plan and submit this to some designated authority for approval before work is begun. Only in this manner can a consistent plan of development be achieved.
A study of the field data might show that these outlet canals





Florida Agricultural Experiment Station


along the range lines could discharge directly into the open Glades without an excessive increase in the lift of the sub-district pumps. If such a plan proved feasible the pumped water would move very slowly over the virgin lands and increase the height of water table in these areas. Also it would not be necessary to construct drainage works much in advance of development.
Some plan of development is urgently needed and when the survey is completed a study should be made with this end in view.
DESCRIPTION OF THE EVERGLADES AREA
The Everglades area includes Lake Okeechobee with its tributary drainage area; the peat lands known as the Everglades, and the sand ridges on either side.
Lake Okeechobee covers an area of approximately 730 square miles. Its shape. is roughly that of a circle with a diameter of 30 miles. The lake occupies a shallow depression the lowest part of which is approximately at sea level. The total tributary area, including the lake surface, is about 5,200 square miles. Of this total the Kissimmee valley accounts for 3,079 square miles. Prior to the construction of drainage works, the lake overflowed into the Glades when the stage reached an elevation of about 21 feet. Before the opening of the St. Lucie Canal in 1926 the recorded stages varied from 13.8 to 21.7 feet. Since that time the range has been from 11.8 to 19.5 feet and the average stage has been approximately 16.0 feet.
The lake is now regulated through two outlets. The St. Lucie Canal to the Atlantic Ocean has a capacity of 5,000 second feet at a 17-foot lake stage, and the Caloosahatchee Canal to the Gulf has a capacity of 2,500 second feet. The combined capacity of the two outlets is sufficient to lower the lake about one foot from normal level in 30 days. The lake is now regulated by the United States War Department and the stages are held as nearly as possible between 14 and 17 feet.
A levee has'been built a'ong the east and south sides of the lake, extending from the St. Lucie Canal to Fish-eating Creek, a distance of about 50 miles. An additional 15 miles of levee also has been built at the north end of the lake near Okeechobee. The elevation of the levee top varies from 34 to 36 feet. This levee will be a protection against huge waves caused by hurricanes.
The Florida Everglades contains about three-fourths of the





Water Control in the Soils of the Everglades


peat lands of the state and is probably the largest continuous body of peat in the world. It is primarily a great sawgrass marsh covering about 4,000 square miles. It lies in a trough about 40 miles wide by 100 miles in length that extends from Lake Okeechobee almost to the end of the peninsula and is bounded on either side by a low sandy ridge. The slope from north to south is about two inches per mile. The elevation near Lake Okeechobee is now about 16 feet above mean low tide.
Prior to drainage, this great peat area was wet during a large portion of the year. The overflow from Lake Okeechobee together with the normal rainfall of about 54 inches per year and some run-off from the higher lands on either side resulted in a high water table which conserved the soil and permitted a slow increase in depth of peat from year to year.
The depth of peat varies generally from north to south. Near the east side of Lake Okeechobee it is 8 to 12 feet deep but in the southern portion of the Glades it is quite shallow. The depth over a large part of the area is now less than three feet, and probably not more than 500,000 acres has a depth of more than five to six feet.
Approximately 85,000 acres of the peat and muck lands of the northern Everglades are now in agricultural use. About one fourth of this is in sugarcane and most of the remainder is used for truck crops. Nearly all the cultivated acreage is served

Fig. 2.-Limerock under peat along the North New River Canal near South Bay.





Florida Agricultural Experiment Station


by pumps. In addition to this there are about 20,000 acres in cultivation near the southeastern edge of the Everglades and approximately one fourth of this acreage is in citrus groves. The peat depth in this part of the Everglades is very shallow and only a small portion of the land is served by pumps.
A considerable portion of the Everglades area is underlaid with a more or less porous deposit of limestone and marl containing marine shells. This is known as the Fort Thompson formation. It underlies the area adjacent to Lake Okeechobee and extends south to about Twenty Mile Bend on the North New River Canal. West of the Palm Beach County line a layer of sand is usually found between the peat and the rock. Most of the remaining portion of the area is underlaid with Miami polite. This is a white limestone which is considerably more porous than the Fort Thompson formation.
The underlying rock formation along the North New River Canal near South Bay is shown in Figure 2. This picture was taken when the water had been pumped from a section of the canal in order to excavate rock f or a new road.

SOILS OF THE EVERGLADES
The soils of the Everglades usually have been divided into three general types called "custard apple," "willow and elder," and "sawgrass." According to a recent classification and survey these three general types are to be known as Okeechobee muck, Okeelanta peaty muck, and Everglades peat, respectively. There are some finer distinctions and a few other types, but this general classification will be adhered to in this report.
By far the greater portion of the peat soils of the Everglades is composed of the partially decomposed remains of sawgrass. The marshy condition of the Glades, during the period of formation, prevented a more complete decomposition of this material. In its original condition the sawgrass peat is a brown fibrous mass in which the partially decayed sawgrass roots can be readily distinguished. These roots are approximately in a vertical position. After drainage, cultivation and weathering gradually transform the top soil into a condition approaching a true muck. The structure then changes into an amorphous mass, the density increases, the color becomes dark, and the rate of seepage through the soil is retarded.
When saturated the soil is a little heavier than water. After






Water Control in the Soils of the Everglades


drainage, the water retained by the soil is equivalent to about three-fourths the weight of the field sample. The oven-dry weight of the soil below the normal water table is about eight pounds per cubic foot of field sample, and the ash or mineral content is about 10 percent of the dry weight. The oven-dry weights of the upper 18 inches of soil, from fields in cultivation for 10 to 15 years, indicate that the density about doubles after a considerable period of intensive use.
In December, 1935, soil samples were taken from 16 locations within a 10-acre field at the Everglades Experiment Station. The figure for each six inches of depth, as shown in Table 1, is an average of 16 samples taken with a brass cylinder six inches long and four inches in diameter. The field has been drained for the past 20 years but had been in cultivation only two years before the samples were taken. At a depth of 13 to 18 inches is a thin layer of slightly plastic, peaty muck, but the remainder of the soil is typical sawgrass peat.
TABLE I.-OvEN-DRY WEIGHT AND ASH WEIGHT OF SOILS AT
EVERGLADES EXPERIMENT STATION.
Depth Of Oven-Dry Weight Ash Weight Ash to OvenSanip e per Cu. Foot per Cu. Foot Dry Weight
Inches Pounds Pounds Percent
0-6 17.5 1.76 10.1
7-12 12.2 1.27 10.4
13-18 11.4 2.00 17.5
19-24 9.5 1.14 12.0
25-30 8.1 0.68 8.4
31-36 7.5 0.62 8.3
37-42 7.8 0.70 9.0
43-48 7.7 0.73 9.5

Average 10.2 1.11 j 10.6

The large ash weight for the 13 to 18 inch depth is due to the thin layer of peaty muck. If the samples for this depth are omitted the remaining samples of sawgrass peat show an average ash weight of approximately 10 percent of the oven-dry weight. The greater dry weight of the upper portion of the soil shows the effect of compaction, weathering and oxidation as the sawgrass peat is slowly changed into a condition approaching a true muck. It is probable that the water table in this field has averaged about 24 inches and has seldom been lower than 30 inches. The samples below the normal water table show little difference in dry weights.







Florida Agricultural Experiment Station


TABLE 2.-SOIL SAMPLES ON SUBSIDENCE LINES-APRIL, 1938.
Results Based on One Cubic Foot of Field Samp-e.
Moist - Oven-Dry Ash Water in IAsh in Oven
Depth We'ght Weight Weight Moist Soil Dry Soil
Inches Pounds Pounds Pounds Percent Percent

Line A
1-6 I 37.4 9.4 1.41 75 15.0
7-12 43.7 6.9 I 0.69 84 10.0
13-18 54.9 9.6 1.26 83 13.1
19-24 63.3 12.3 2.08 81 16.9
25-30 60.7 9.8 1.35 84 13.8
31-36 I 59.7 8.1 0.94 86 11.6
37-42 63.4 7.8 0.90 88 11.6
43-48 I 65.2 8.6 0.95 87 11.0

Line H
1-6 59.8 23.0 2.78 62 12.1
7-12 I 64.6 14.4 1.90 78 13.2
13-18 62.9 10.9 1.37 83 12.6
19-24 64.1 12.4 2.53 81 20.4
25-30 62.2 8.8 0.86 86 9.8
31-36 1 64.1 7.6 0.79 98 10.4

Lawn
1-6 57.2 14.8 2.46 74 16.6
7-12 61.8 12.6 1 1.75 80 13.9
13-18 62.9 10.3 1.35 84 13.1
19-24 64.6 12.9 2.54 80 1 19.7
25-30 62.5 8.6 0.76 86 1 8.8
31-36 63.1 7.4 0.72 88 9.7

Remarks
Line "A" in Sec. 10 at Everglades Experiment Station. Virgin sawgrass
soil. Water table approximately 3.5'.
Line "H" at Everglades Experiment Station near Well 12. Sawgrass soil
in cultivation since 1924.
Line over grass lawn at Everglades Experiment Station. Sawgrass soil.

Table 2 shows three sets of soil samples taken from lands at the Everglades Experiment Station in April, 1938. The high ash content of the 19 to 24 inch sample in each set is due to the thin layer of peaty muck referred to above. Line A is on virgin sawgrass soil, South of the Experiment Station. Line H is on land which has been in truck crops for about 14 years and the "Lawn" line is on soil which has been covered with St. Lucie grass for nearly the same period.
The Okeechobee (custard apple) or plastic muck of the Everglades covers about 30,000 acres located along the east and south sides of Lake Okeechobee. It is thought to have been formed from the residue of succulent water plants deposited during a period when the area was continuously under water. The ash or mineral content varies from approximately 35 to 70 percent of the oven-dry weight. This soil is dark in color and homo-







Water Control in the Soils of the Everglades


geneous in structure. It was commonly called "custard apple" muck on account of the custard apple trees which originally covered it. The proximity of this soil to the lake probably accounts to some extent for the high mineral content. In its original state this soil was less fibrous and contained more of the elements essential to plant growth than did the sawgrass peat. Hence it was the first of the Everglades lands to be used since it was also somewhat higher and therefore had better natural drainage.

TABLE 3.-SOIL SAMPLES ON SUBSIDENCE LINES-APRIL, 1938.
Results Based on One Cubic Foot of Field Samp'e.


Moist Oven-Dry
Depth W& ght Weight
Inches Pounds Pounds

Line S
1-6 54.2 18.4
7-12 55.3 17.7
13-18 63.8 17.0
19-24 66.0 18.0
25-30 65.3 13.2
30-36 63.1 9.6

Line 0
1-6 47.2 27.5
7-12 40.6 15.3
13-18 47.6 14.3
19-24 55.6 18.0
25-30 62.0 24.3
31-36 69.4 24.6

Line E
1-6 52.2 31.7
7-12 60.9 28.2
13-18 55.5 23.6
19-24 59.4 23.4
25-30 61.8 19.3
31-36 60.8 13.6
37-42 70.8 11.1
43-48 63.1 9.1

Line D
1-6 58.4 41.7
7-12 53.6 24.1
13-18 54.2 20.8
19-24 56.1 18.7
25-30 64.1 15.6
31-36 69.8 16.0
37-42 70.4 18.4
43-48 72.8 18.0


Ash Weight
Pounds


5.46 4.11 7.80 8.19
3.54 1.34


14.85 7.19 7.12 11.35 18.30 15.15


15.88 19.38
17.04 16.31 10.81 2.82 1.55 0.96


26.52 15.91
13.40 12.29 7.80 10.53 10.30
12.22


Water in Moist Soil
Percent


66 68

70

85




70 68 61 65


39
54 58 61
69 78
82 86


29 55 62 67 76 77
74 75


Ash in Oven Dry Soil
Percent


29.7 23.2
45.9 45.5 26.8
14.0


54.0 47.0 49.8 63.1 75.3 61.6


50.1 68,8 72.2 69.7 56.0 20.7
14.0 10.5


63.6 66.0
64.4 65.7 50.0 65.8 56.0 67.9


Remarks
Line S near Well 18 at Canal Point. Willow and elder soil. Line 0 near Well 7 at Canal Point. Okeechobee muck. Line E at Well 10 on Boe farm near Pahokee. Okeechobee muck. Line D at Well 8 near Bean City. Okeechobee muck.






Florida Agricultural Experiment Station


The samples from Lines 0, E and D as shown in Table 3 are typical Okeechobee (custard apple) muck. The low ash content of the bottom 18 inches of soil on Line E is due to a layer of sawgrass peat. At a depth of 25 to 30 inches on Line 0, and 13 to 18 inches on Line E, a two or three inch layer of yellow and grayish material was encountered. Tests showed this to be ash; hence the high mineral content of the samples at the above depths. Such ash deposits found in this location and elsewhere in the Everglades indicate that destructive fires occurred in this area in the distant past.
Between the Okeechobee muck and the Everglades peat is an intermediate soil type, Okeelanta peaty muck, commonly called "willow and elder" land. This is somewhat similar to the sawgrass peat but has a higher ash content and usually a thin, well defined layer of plastic muck within the top two feet of the profile. The zone of Okeelanta peaty muck is not clearly defined but probably covers about 40,000 acres. Line S, shown in Table 3, is on soil of this type.
In addition to the three types of soil previously mentioned there is a substantial area of Loxahatchee and Gandy peats. The former type was formed from a mixture of sawgrass residue and other vegetation, including water grasses and lilies, and largely comprises the so-called "slough areas." These areas are usually quite wet and are probably best suited for wild life reserves. There is a large body of this land along the east side of the Glades














J
Fig. 3.-Shrinkage of organic soils. Center cylinder shows original size. Sample on left is Everglades peat; sample on right is Okeechobee (custard apple) muck.






Water Control in the Soils of the Everglades


between the Hillsboro and West Palm Beach canals. The latter type is composed of woody material derived from various species of bay and myrtle, and occupies the small islands and ridges commonly associated with the sloughs that are made up of the Loxahatchee type.
Peat soils are subject to much shrinkage when dried and will not expand to original volume when water is again added.
Figure 3 shows two soil samples which were oven-dried. The center cylinder shows the original size of the samples. The one on the right is Okeechobee (custard apple) muck; the one on the left is Everglades peat.

SUBSIDENCE OF PEAT SOILS

As the subject of subsidence in the Everglades has been covered in special reportS,3 only a summary will be given here.
Peat soils are formed by the slow accumulation of plant residues under very wet conditionS.4 The complete decomposition of the plant material is prevented by the high water table usually found in swampy areas. After the natural water table is lowered by drainage the ground surface elevation begins to fall. This subsidence is due to loss of water and to slow oxidation; also to compaction of the top layer by cultivation.
After a virgin area is drained the subsidence is very rapid at first, but decreases with time. Figure 4 shows the rate of subsidence along a reference line near Okeelanta, Florida. A small portion of the loss shown is due to fires, but by far the greater portion is due to subsidence resulting from drainage.
Most of the cultivated lands of the northern Everglades have subsided approximately five feet since drainage was begun about 25 years ago. The rate of subsidence of sawgrass soil, in recent years, has averaged about one inch per year. Okeechobee (custard apple) muck subsides at a somewhat slower rate. A large number of reference lines have been established in the northern Everglades for a continued study of this subject.
The data so far available indicate that the rate of subsidence is approximately proportional to the average depth of water

'Clayton, B. S. Subsidence of peat soils in Florida. Bureau of Agricultural Engineering. U.S.D.A. Report No. 1070, 1936. (Mimeog.)
'Allison, R. V., 0. C. Bryan, and J. H. Hunter. The Stimulation of plant response on the raw peat soils of the Florida Everglades through the use of copper sulphate and other chemicals. Florida Agr. Exp. Sta. Bul. 190: 33-80. 1927.






Florida Agricultural Experiment Station


S g.r 19214, o . 20.3 ,


- ' A , 610. , -I

J -,, 191, E I 17.15
SJ-,e 925, [lev 16 78(only I Of lIte


FAS.1933,U-$05.50
I L



0 20 40 00 0 100 20 4 0 Io 200 220 290
Monts oson,,,a, a
Fig. 4.-Surface subsidence of Okeelanta peaty muck near the Bolles Canal.
table.5 As the lowering of the water table exposes a greater volume of soil to slow oxidation a greater subsidence loss naturally occurs.
Total subsidence following drainage does not appear to have been much affected by the type of crop grown, as lands planted to cane, truck crops, or grasses have subsided approximately the same total amount. Even virgin lands exposed to pump drainage or near the large gravity canals have subsided about four feet.
A large number of soil samples have been taken from various reference lines. These have been oven-dried and the density and ash content determined. The results indicate that the top 18 inches of soil on fields used intensively for truck crops has doubled in density in about 10 years of use. The soil densities, based on oven-dry weights, decrease from the top downward. In virgin soil areas which have subsided almost as much as the cultivated fields, the density of the top soil shows very little increase over that below the permanent water table. For equal subsidence a greater loss of soil mass has occurred in the drained but idle lands. It, therefore, appears evident that the land should be placed in cultivation as soon as possible following drainage in order to conserve the soil.
'Roe, H. B. A study of influence of depth of ground water level on yields of crops grown on peat lands. Minn. Agr. Exp. Sta. Bul. 330: 1-32. 1936.





147ater Control in the Soils of the Everglades


Much of the virgin land in the northern Everglades has subsided from three to four feet due to gravity drainage by the large canals and there has been little or no increase in density in the upper portion of the soil. Subsidence levels over similar sawgrass land near Pahokee show that after pump drainage was established and the area was planted to cane a further subsidence of 1.8 feet occurred during 10 years of use. It is probable that approximately an equal amount of subsidence will occur during the next 20 years, making the loss after 30 years of use about 3.6 feet. It is, therefore, important that before new areas of virgin lands are brought into use, the depth of soil and probable subsidence should be carefully considered in planning the drainage works.
From the records available it is estimated that the average water table in the cultivated lands of the northern Everglades is approximately 2.5 feet. This may vary from surface to a depth of four feet, due to the variation in season, rainfall and the amount of pumping. If the water table were held to an average depth of 1.5 to 2.0 feet, the subsidence would be proportionally reduced. Aside from maintaining a higher water table, there appears to be no practical way of decreasing subsidence in peat soils.
SEEPAGE THROUGH PEAT SOIL
There is considerable evidence that the seepage movement in the Everglades is largely through the porous rock and sands beneath the peat. Typical profiles of the water table between drainage ditches approximate a rather flat curve over the major portion of the line, but about 100 feet from the ditches the profiles show a steep slope, indicating the resistance of the peat to lateral seepage. In porous material like sand the slope would be much flatter. It was also noted that the completion of the new lake levee, with the probably impervious seepage fills beneath, apparently had no substantial effect on the ground water table of the protected lands.
In the spring of 1939 the water in the North New River Canal was a f oot or more below the rock over a long stretch below Okeelanta. Well readings on the west side of the canal showed a water table slope towards the canal for a distance of at least two miles back (Fig. 5). From the canal to a point a half mile back, the seepage gradient rose approximately two feet. It was thus evident that the seepage water from the peat lands on either side reached the canal through the porous rock formation.












L- 2 MIes Soth f B,e C
west, pra Hghoy NO 26

w e tb e EI-1111, 9,* 'S











0, 9.049 0,4944 0,0l 0.'9$O 4.0 ,o 0 09'10 oo IO010















es omHghwo NO .6 W-1og,0To e9 1o0 t9o, ,kd W5
-4 19 2 1 4 S--- 3,4


Fig. 5.-Profiles showing water table in virgin peat land after a very dry 'period.






Water Control in the Soils of the Everglades


Figure 5 shows surface profiles and water tables along two lines. One begins at the North New River Canal two miles below the Bolles Canal near Okeelanta and the second begins four miles south of the Bolles Canal. Both lines extend two miles to the west over sawgrass land. The depths to water table were very close to maximum, as the rainfall for the preceding year was one of the lowest recorded.
To make a rough comparison of the rates of seepage through vertical and horizontal sections of sawgrass peat, three samples were taken in brass tubes four inches in diameter. One vertical sample was taken from the top 18 inches of soil, a second from the 18 to 36-inch depth, and a horizontal sample was taken at a depth of three feet. The land has been drained by pumps for 14 years but has been in cultivation for only a few years. The vertical samples were 18 inches long. The horizontal sample after compression of several inches due to forcing the tube through the soil was 11 inches long. The tubes were set up so that the difference in level of the inflowing and outflowing water was held constant at 19 inches.
The average depth of water passing through the top 18-inch sample was 0.30 foot per day, that through the 18 to 36-inch vertical sample was 27.3 feet and that through the horizontal sample was 0.25 foot per day. The second vertical and the horizontal samples were both in the brown fibrous peat, and the wide difference of seepage movement through them doubtless is due to the structure of the partially decayed sawgrass residue which provides small openings along vertical lines. The seepage through the top sample of soil was not much greater than that through the horizontal one. The top soil is changed by weathering and cultivation into a very finely fibrous peat. The density is increased and the original vertical seepage lines are largely obliterated. Hence the decrease in rate of seepage movement. This change is evident in old cultivated fields for, subsequent to a heavy rain, surface water remains for extended periods after the ditches are pumped to a low level.
The rates of seepage through the samples were doubtless affected to some extent by compaction. However, the differences were so great that it seems reasonable to conclude that the seepage movement through the soil is much greater in a vertical than in a horizontal direction.





Floi'ida Agricultural Experiment Statiou


CLIMATOLOGICAL DATA
RAINFALL
On the peat lands near Lake Okeechobee there are four rainfall stations with records of more than 14 years. These are located at Canal Point, Moore Haven, Everglades Experiment Station, and the Shawano Plantation. Also, there was a record at Ritta from 1914 to 1930, inclusive, but this station was discontinued in 1930. Ritta was located on the south shore of the lake about two miles west of the Miami Canal.
The Station at Canal Point is maintained by the Cane Breeding Experiment Station of the U. S. Department of Agriculture; the one at Moore Haven by the U. S. Weather Bureau; and the one at Shawano by the Brown Company. Tables 4, 5, 6 and 7 show the monthly and annual rainfall for the four stations. Maximum, minimum and average monthly and annual rainfalls also are shown.
The average rainfall for the four-month period from June to September at the Everglades Experiment Station is 60 percent of the mean annual precipitation and at the other three stations it is 59 percent of the annual amount. December is the driest month at each of these stations, with an average of about one inch.
Two of the longest rainfall records in South Florida are those at Fort Myers and Miami. A 70-year record at Fort Myers, including 1938, shows a mean annual precipitation of 51.84 inches, a maximum of 82.64 inches, and a minimum of 32.85 inches. At Miami a 51-year record shows a mean annual of 59.51, a maximum of 89.07, and a minimum 33.15 inches.
The record shown for the Everglades Experiment Station covers 14.5 years. The maximum rainfall for a calendar year was 66.14 and the minimum was 40.99 inches. However, the maximum rainfall during a consecutive 12-month period was 73.81 and the minimum was 34.98 inches.
Table 8 shows the record of excessive precipitations at the Everglades Experiment Station for the years 1935 to 1938, as determined from the charts of a weighing rain gage. On'y 15 storms of two inches or more were recorded during these four years. The greatest rate for one hour was 3.25 and that for two hours was 3.35 inches. The Weather Bureau record at Miami for the period 1912 to 1930 shows a maximum of 3.50 in one hour and 6.11 inches in two hours. These Miami records were obtained from November storms.










TABLE 4.-RAINFALL IN INCHES AT CANAL POINT.


Year Jan. Feb.


19 23 1924 1925
1926 1927 1928
1929 191) 90 1931 1!;3,2
1!9"
1934 19835 193 6 193 1938

Av. Max. TV[ .


1.53 3.00
4.46 6. 19. 0.3")) 0. 19
1.34 2.51 2.05 0.26
1.54 0.25 0.16
2.40 4.30 0.12

1.92 6.19
0.12


0.14 2.23
2.24 2.25 1.80 1.38 0.07 3.03 0.91 2.38 0.35 5.36 2.81 5.69 1.81
0.84
2.08 5.69 0.07


Mar.


0.34 3.71
2.46 1.63 2. 37
3.48 0.60
4.32 4.27 0.87
4.7*3 2.77

4.88 1.08

2.56


A


pr. May


55 7.06 17 2.27 50 9.73 33 1.54 08 1.54 72 3.10 32 5.43 25 6.10 71 3.05 67 3.49 42 1.31 .64 6.27 .45 0.76 .39 6.10 .36 1.92 ,45 3.13

.56 3.93 .25 9.73 .39 0.76


June


6.62
4.84 8.62 8.62 6.31
5.42 11.74 16.96
0.49 11.26 7.62 7.96 6.11
14.29 4.44 6.67

8.00 16.96
0.49


July


8.48 11.08 8.47
7.45 7.32
14.57 11.26
4.08

4.91
14.02 5.20 3.98
5.44 14.62 7.28

8.22
14.62 3.33


IAug. ISept.


9.95 1.85 7.12 5.72
8.14 14.13 6.31 3.07
4.67 9.91 8.51
8.14 3.62 i 8.*59
f).37 5.52

7.16
14.13 1.85


8.31


14.82 3.31
16.45 10.70 5.36
5.64 2.40 8.16 11.69 11.90
4.08 5.88
8.45

8.26
16.45 2.40


Oct.


2.17 18.'14 2.25
1.24 3.35 0.77

5.14 4.43


2.40* 4.44 2.84 6.50 3.69

4.39 18.14 0.77


Nov.


0.43 0.89) 1.67 0.72
0.49 1.24 0.69
0.67 0.70 25.09
1.84 0.55* 0.57 5.08 2.23 0.97

2.74 25.09
0.43


Dec.


0.45 0.15 1.99 0.10
0.40 0.*20 1.08 2.77
4.62 0.16 0.09
0.58*
1.22 1.65 0.26 0.10

0.99
4.62 0.09


Annual To a]

48.03 61.30 56.60 53.61
36.44 62.65
54.62 63.29 39.87 67.91 58.95 58.81
41.19 59.82 59.57 38.30

53.81 67.91
36.44


*Rainfall for month estimated from records of nearby stations.










TABLE 5.-RAINFALL IN INCHES AT MOORE HAVEN.


Year 1Jan. 'Feb.


1919 1
1920 2
1921 0
1922 0
1923 0
1924 1
1925 2
1926 3
1927 G
1928 C
1929 C
1930 (
1931 2
1932 [ 1933 1
1934 1
1935
1936 1937 1938

AV. Max.
Min. (


3.70 2.59 1.99*
1.10
0.49 1.75 1.88 1.19
2.09 2.31
0.14 3.23
0.76 3.13 0.19
2.89 1.00
4.97 1.70 0.57

1.88
4.97 0.14


Mar.



2.83 0.53
0.84* 0.74 0.62 3.38
2.04 1.12 1.70
2.46 0.52
4.76
5.90 2.87 3.88 2.73 0.03 1.95
4.83 0.34

2.20 5.90 0.03


Apr. May June


2.05 0.62 5.13 0.66"
0.46 3.55 3.55 3.92 3.82
2.02 1.52 1.55
4.12 3.44 1.76 6.92
2.22 5.18 2.55
4.89 0.21

2.86 6.92
0.21


0.35 6.70 3.05 5.86
5.14 11.70
1.21 6.43 2.13
1.94 4.19 2.73 11.,33 1.59 6.05 3.89
6.43 3.57
5.41 4.94
6.28

4.81 11.70 0.35


2.55 10.59
6.84
2.16* 9.82 12.52 8.86 8.69 15.05 10.79 8.12 9.35 17.'85
1.20 4.96 4.66
4.36 5.84 14.59 3.59
7.40

8.08 17.85
1.20


July IAug. ISept. Oct.


2.87 6.88 15.21 5.11: 7.63
7.54 11.77
4.68 11.24
5.79
5.43 8.44 4.72 2.68 6.25 5.36
8.48 5.09 2.99 13.79 8.20

7.15 15.21 2.68


6.94 4.12 4.51
3.65* 6.72
10.04 4.76 9.83
6.24 8.61
11.82
4.93 11.61
10.34
15.71 5.77 6.20 5.50 5.79
4.71 2.39

7.15
15.71 2.39


10.83 2.72 2.78 0.90 3.18 2.72 2.16* 8.35 14.93 10.70 4.23 1.39 8.41 13.39 1.08 1.54
8.90* 1.93* 6.99 4.12 14.60 0.47 13.45 1.71 11.26 6.33 5.06 1.94 5.99 2.93 2.75 5.18
4.18 5.54 9.53 1.42 11.51 3.55 4.48 8.72 2.23 3.92

7.05 4.26 14.93 13.39 1.08 0.47


*Rainfall for month estimated from records of nearby stations.


0.98
4.86 4.54 2.19 1.56
0.21 0.30 0.93
1.74*
0.38 0.97 1.27
0.45 0.08 3.28 0.92 3.58 1.71 0.58
5.47 1.52

1.79
5.47 0.08


Annual Total


46.38 51.03 33.67 60.39
52.89 60.52
46.06 56.95
44.93 52.62
46.30
78.48 35.92 54.97
41.45 48.20 40.87 57.30 59.63
33.78

50.12
78.48 33.67


0.73 1.15 0.63 0.25 0.89 0.28 0.09 2.83 0.10 0.39 0.31 1.39 2.33 0.35 0.07 0.28 0.26
1.48 1.18
0.44 0.11

0.74 2.83 0.07














Year Jan.


1924
1925 3.58
1926 I5.39 1927 I0.32 1928 i0.31 1929 1.20
1930 I1.92 1931 2.31
1932 1.72
1933 0.64
1934 0.14
1935 0.30
1936 1.91
1937 2.97
1938 0.46

Av. 1.65
Max. 5.39
Min. 0.14


TABLE 6.-RAINFALL IN INCHES AT THE EVERGLADES EXPERIMENT STATION.

Feb. iMar. Apr. May June July Aug. ISept. Oct. Nov.


6.59 3.72 8.49 15.84 0.62
2.49 2.37 3.78 9.38 5.61 5.56 12.;36 4.17 0.49 1.14 0.66 1.48 1.81 3.69 9.29 10.57 10.40 13.60 3.58 0.91 2.90 2.18 2.44 3.19 7.08 12.77 11.45 6.41 4.50 0.42 1.66 3.83 1.78 2.61 9.20 8.25 1 1.3)1 19.04 1.46 1.07 0.49 1.70 2.61 8.92 11.11 7.32 :3.79 12.23 4.71 4.13 2.40 6.32 6.03 4.43 19.61 6.28 :3.74 3.58 4.94 0.56 1.17 3.93 4.41 3.16 0.59 3.05 7.67 10.68 4.16 0.51 2.13 1.56 1.54 4.69 16.01 3.93 r10.59 7.43 3.68 12.36 0.38 5.42 6.90 4.04 9.51 3.85 12.75 11.89 5.30 4.50 1.91 7.10 3.11 5.20 10.15 10.09 12.41 7.44 3.22 0.65 1.32 0.41 5.32 1.08 8.45 6.37 6.54 10.88 5.71 0.36 4.04 2.40 1.96 6.39 18.61 6.09 5.33 5.84 1.65 9.17 1.21 5.87 6.00 3.38 7.74 7.65 7.89 8.35 4.92 2.08 1.14 1.87 0.32 4.52 5.44 8.85 2.65 10.09 2.78 1 2.66

1.71 3.32 3.43 4.62 9.89 7.15 8.17 9.34 4.46 2.74 4.04 7.10 6.90 9.38 19.61 12.77 12.75 19.04 15.84 12.36 0.38 0.41 0.32 1.08 0.59 3.05 2.65 3.58 0.49 0.36


Dec. Annual
To'al

0.22
2.84 53.77
0.55 61.93
0.42 54.08
0.25 60.77
0.92 59.13
3.54 63.35
1.11 42.75
0.50 66.14
0.12 65.30
0.82 62.24
2.07 48.81
1.18 64.57
0.38 58.44
0.21 40.99

1.01 57.30
3.54 66.14
0.12 40.99














TABLE 7.-RAINFALL IN INCHES ON THE SHAWANO PLANTATION.


July


Jan.



14.86
0.37 0.83 2.61


IAug. Sept. Oct. Nov.


7.38 i2.42 0.63 .1R


6.74 2.68 5.36 5.00 0.99
4.51 3.15 7.28 0.57
3.42 0.00

3.42 7.28 0.00


4.58 3.58 1.08 6.'20
2.47 5.29
4.11 11.30
2.01 6.11
4.46 4.25 1.81



0.63


12.02 8.16
114.66 5.66 2.83 8.32 10.83 8.59 9.85 11.36
5.47 2.00 3.73

7.92
14.66
2.00


Mar.


5.19 5.27 7.51 3.20
4.65 2.06 10.36 9.17
4.13 8.19 13.37 8.20

6.73 13.37 2.06


May I June


Year


1925 1926 1927 1928 1929 1930 1931 1932 1933
1934 1935 1936 1937 198

Av. Max. Min.


Dec. L71


6.64 4.91 16.48 10.43 6.14 9.31
4.00 8.03
5.14 12.81 5.03
10.45 6.72

7.75
16.48 2.42


5.85
4.94 8.16
6.64 9.03
1.20 8.45 6.52 5.07 10.13 17.72 7.,13 8.18

7.62 17.72
1.20


Annual Total


50.89
36.49 62.04 53.27
44.24 45.78
46.62 59.11 50.10 59.06 61.56 55.71 39.92

51.15


1.45 0.51 1.05 2.92 0.96 0.96
5.64 3.17
0.54 0.61
5.24 1.45 1.77

2.15
5.64 0.51







TABLE 8.-EXCESSIVE PRECIPITATION AT THE EVERG'ADES EXPERIMENT STATION 1935 TO 1938, INCLUSIVE.


Accumula
Date
1 hr. 2 hrs.

6/25/35 0.94 3.00
8/9/35 0.56 1.95
0.07 0.11
9/:)/35 0.62 0.90
[1.16 1.23
6/336 2.10 2.45
f0.11 0.38
6/15/36 1.80 2.12
3.24 :3.70
116 /3 6 0.10 0.10
. 1.71 1.74
l / 7/,36 0.10 0.12
1.88 1.96
11/12/36 0.10 1.25
1/13/37 0.10 0.14
3/31/:37 0.98 1.96
4.63 4.68
1/6/37 0.58 0.58
6/8/37 2.10 2.26
7 /1 /37 0.24 0.30
2.50
9/5 /37 2.40 2.65
9 /2 /38 2.26 2.32


ted Amount


3 hi's.

3.73 1.97 0.18 0.92 1.33 2.62 0.62 2.44 4.11 0.10 2.24 0.17 2.00 3.45 0.84 2.25

0.73 2.37 0.30


s of Rainfall (in Inches) During Periods

4 hrs. 5 hrs. 6 hrs. 7 hrs. 8 hrs.

3.84 2.00
0.18 0.21 0.2;3 0.42 0.60
0.95 0.97 1.13 1.16 1.16
1.50 1.51 1.52 1.81 2.01

0.82 (U. L.08 1.17 1.43
2.52 2.66 2.85 .00 3.10
4.14 4.18 4.22 5.38 6.55
0.20 0.20 0.22 0.22 0.82
2.45 2.52 2.54 2.79 :3.05
0.30 0.31 0.31 1.10 1.68
2.07 2.09 2.10 2.10 2.12
1.40 1.77 1.78 2.14
2.58 3.92 4.36 4.50 4.50
1.37 2.;M,: 3.28 :1.38 3.84
2.44
0.32 0.70 1.19 2.20 2.42


Note.-- Rains of less than 2.00 inches in 24 hours are not shown. Tabulations of rains of more than 8 hours are shown ii, two or more lines ,o,,cted by brackets. In such cases each amount in the second line includes the total for the eight-hour period in the line above.
The highest amount in a one- or two-hour period is not shown unless two inches or more fell in two consecutive hours.


Highest Amount
(in Inches)
1 hr, 2 hrs.


2.38








TABLE 9.-RAINS OF Two INCHES OR MORE AT THREE STATIONS NEAR LAKE OKEECHOBEE.

Rain Jan. Feb. Mar. Apr. May June July 1Aug. Sept. Oct. Nov. Dec.
(Inches)III
Everglades Experiment Station, 1925 to 1938, Inclusive


2-3 2 3-4
4-5
5-6
6-7
9-12 -


U. S.

2-3 3 1 2
3-4


22


Cane Breeding Station,


1 7


5-6 6-7 7-8
21-22


9 3 5 o 2
4 1 1 2 1
- - 3




Canal Point, 1923 to 1938, Inclusive


5 13 1 2 1
1
2 21


Moore Haven, 1918 to 1938, Inclusive (see note)


10 1, 7 6
2 2 4
2 1


Note.-There was no record at Moore Haven from Feb. to Sept. 1921, and from Sept. to Nov. 1926.


2-3
3-4 4-5 5-6 8-9


1


1
1


5


Z2






Water Control in the Soils of the Everglades


One of the heaviest 24-hour rainfalls ever recorded in Florida occurred at Canal Point in November, 1932. The record at the U. S. Cane Breeding Station showed 21.92 inches. Nearly all the rain fell between 11:00 p.m. November 6, and 7:00 a.m. November 7. During the preceding day 1.90 inches was recorded, making a total of 23.82 inches for 48 hours. Other rain gages within a few miles of this station showed amounts varying from 19.0 to 21.2 inches in 24 hours. The heaviest 24-hour rainfall at the Everglades Station was 10.90, during the same November storm. The maximum 24-hour rainfall recorded within the state, 23.22 inches, occurred at New Smyrna in October, 1924.
Table 9 shows the number of rains of two inches or more which have occurred in 24 hours at the Everglades Station, at Moore Haven, and at Canal Point during the periods of record. The number of rains are shown according to size groups as indicated in the first column. The data show an average of about four rains of two inches or more per year at each station and approximately 60 percent of these rains have occurred during the four-month period from June to September, when there is little or no farming.
Rains of four inches or over have occurred eight times in 14 years at the Everglades Experiment Station; 13 times in 16 years at Canal Point; and seven times in 21 years at Moore Haven,

EVAPORATION AND TRANSPIRATION
To determine the evaporation and transpiration from sugarcane and grasses, records have been kept for the years 1934 to 1938, inclusive. For this purpose four large steel tanks were used. Each tank is four by 12 feet in area by four feet deep and is set in the ground to a depth of 3.5 feet. The bottoms of the tanks were first covered with a three-inch layer of crushed stone about one inch in size so as to allow the water table to more readily equalize when water is added or withdrawn. The excavated peat soil was replaced in layers to an elevation about six inches below the tops of the tanks. The water table in the tanks was kept at a near-constant elevation by adding or withdrawing water as needed, using a two-inch bilge pump for this purpose. The water added or withdrawn was measured in small tanks of such size that an inch over the large tanks was equivalent in volume to a foot in the smaller tanks. The rainfall was measured in a standard rain gage placed nearby. The wind






Florida Agricultural Experiment Station


movement, shown in total miles per month, was recorded on the top of a two-story building about 1,000 feet from the tanks. The crops planted in the tanks were surrounded by other plantings on the outside to protect the tank growth from an excessive exposure to wind and sunlight and thus approximate fie'd conditions as closely as possible. The open pan evaporation data were obtained from a standard U. S. Weather Bureau open pan located near the steel tanks. Tables 10 to 14 show the evaporation and transpiration records for the years 1934 to 1938, inclusive.
The cane record covers a period of five years. The total evaporation and transpiration for the four-month period from June to September was approximately 49 percent of the total for the five-year period and the total for the two-month period from July to August was 27 percent of the five-year total. The ration of cane cut in January does not reach much size till June and the period of heavy growth extends through September. During these summer months the days are long and the temperatures high; hence the heavy evaporation. The average annual loss from Tank 1, f or the period of 1934 to 1937 inclusive, was 46.8 inches. The 1928 record is not included as the ground was kept heavily mulched during that year.
In field practice the cane is usually burned over before harvest and after cutting the fields are fairly well covered with trash from cane tops. This covering is probably a little thicker than that on the tanks. The water table in the tanks averaged about 1.5 feet, while that in the cane fields probably averages about two feet. Hence the field evaporation would be a little less than the figures shown. It is estimated that the evaporation and transpiration over large cane areas is between 42 and 45 inches per year.
During the years 1937 and 1938 evaporation records were kept for a tank covered with three or four inches of cane trash. The water table averaged approximately 1.4 feet. The evaporation for the first year was 12.2 inches and that for the second year was 9.1 inches. The record for 1937 shows that the evaporation from the mulched -tank was about 30 inches less than that from a bare soil tank which was partially shaded by cane around the tank. During the year 1938 the cane tank was also covered with a similar mulch of cane trash in order to determine the approximate transpiration through the cane. The results indicated that 25.9 inches of the total loss from the cane tank was transpiration. The cane yield was 37.4 tons per acre. Calculations









TABLE 10.-EVAPORATION AND TRANSPIRATION FROM TANKS AND OPEN PAN FOR YEAR 1934, EVERGLADES EXPERIMENT STATION, BELLE GLADE, FLORIDA.


Wind Motion


Miles

4,600 5,070 5,650 4,950 4,100 3,860 3,330 3,410 3,540 3,980 4,250 4,220


Average Evaporation and Transpiration
Depth to Cane Cane Bare Soil Open
Water Tank 1 Tank 2 Tank 3 Pan
Feet Inches Inches Inches Inches


2.05 1.94 1.87
1.61 1.76 1.37 1.66 1.35 1.67 1.93 1.99 1.96


1.95 2.63 2.91 4.62 3.66 5.37 7.32 6.51 5.67 5.61
3.48 1.67


2.39 2.86

4.62 3.97 4.59 4.65 4.74 3.69 3.41 2.31 2.05


3.63 3.69 5.56 6.96 6.40 6.19 7.12 6.70 5.77
5.73 4.03 3.49


Mean
Rainfall Temperature
Inches F. �

0.14 63.8
1.91 62.3
7.10 66.4
3.11 70.2
5.20 75,3
10.15 78.5
10.09 79.2
12.41 80.0
7.44 79.6
3.22 76.1
0.65 68.0
0.82 63.8


Year . 50,960 1.76 51.40 49.32 42.65 65.27 62.24 71.9

Note.-Cane in Tank 1 was a large barrel type (P.O.J. 2725) and that in Tank 2 was a medium barrel type (Co. 281). Both canes were planted Feb. 1. 1934, and were cut Dec. 13, 1934. following a hard freeze on Dec. 12. Cane in Tank I produced 46.4 tons per acre and tbat in Tank 2 Produced 33.0 tons per acre. Tank 3 contained bare soil without shade. Tanks 1 and 2 were surrounded with cane on the outside, for a windbreak.


Month


Jail. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.











TABLE 11.-EvAPORATION AND TRANSPIRATION FROM TANKS AND OPEN PAN FOR YEAR 1935, EVERGLADES EXPERIMENT STATION, BELLE GLADE, FLORIDA.

Wind Average Evaporation and Transpiration Mean
Month I Motion Depth to Cane Cane Bare Soil IAlfalfa i Open Rainf all TemperaIWater Tank 1 Tank 2 Tank 3 1Tank 4 Pan ture
Miles Feet Inches inches Inches Inches Inches Inches i F.

Jan. 5,179 18 0.93 0.87 2.08 1 1.74 3.81 0.30 63.4
Feb. j. 4,143 1.78 1.76 1.62 2.24 2.46 4.25 1.32 63.1
Mar . 5,087 1.79 1.98 1.64 2.94 2.23 6.52 0.41 68.8
Apr. _. 4,434 1.38 3.15 4.86 3.81 3.06 7.50 5.32 71.1
May -. 4,073 1.82 2.94 2.73 2.79 I 4.22 8.84 1.08 76.1
June . 2,990 1.46 4.11 4.14 3.54 1 5.01 6.55 8.45 77.3
July ----. 3,851 1.67 5.83 6.26 4.16 6.70 7.38 6.37 79.3
Aug. ._.2,956 1.55 6.54 7.16 4.3 7.28 7.02 6.54 80.1
Sept . 4,1 1.28 5.64 5.28 5.55 3.69 5.54 10.88 79.1
Oct.-- 4,898 136 5.30 5.46 3.81 3.60 5.37 5.71 75.9
Nov. 4,148 1.82 5.25 4.11 1.50 2.49 4.32 0.36 69.0
Dec . . 4,820 1.65 3.08 2.42 2.42 2.64 3.50 2.07 56.4


Year . 50,690 1.61 46.51 46.55 39.21 . 45.12 70.60 48.81 71.6

Note.-Cane in both tanks was the same type as in previous year. S dl was covered with dry cane leaves until Jan. 21. thus reducing evaporation for a period of three weeks. Cane growth was stopped by killing frost o Dec. 1 and crop was harvested on Jan. 14, 1936. Cane in Tank 1 was retarded by wireworms. eThe yield was 42.0 tons per acre. Tank 2 was re,)ianted on April 15. because of wireworm damage. The cane yield was 28.6 tons per acre.
Tank 3 contained bars soil partially shaded by cane around the outsi 'e. but the shade was not equivalent to usual cane field conditions.
Tank 4 had soil substantially bare prior to April 15 when alfalfa was planted. At first the alfalfa made good progress but the stand deteriorated during the summer, and only a scattered growth remained in the fall; he.ice the drop in evaporation.








TABLE 12.-EVAPORATION AND TRANSPIRATION FROM TANKS AND OPEN PAN FOR YEAR 1936, EVERGLADES EXPERIMENT STATION, BELLE GLADE, FLORIDA.


Av. Depth to
Month Wind Water in Ft.
Motion Tanks Tank
r1,.3& 4 2
IMiles

Jan - -------- 4410 1.38
Feb._. 4994 1.21
Mar - ---- 5050 1.42
Apr. __---- 4520 1.47 0.72
May _. 4709 1.24 0.75
June .3526 1.00 0.59
July ------ 3943 1.47 1.00
Aug. 3337 1.46 1.00
Sept - -- ---: 2707 1.31 0.97
Oct._ 3509 1.46 1.08
Nov - ------- 3755 1.14 0.86
Dec.------ 3850 1.42 1.02


Year ------ 4 8,3 10 1.33-


Evaporation and Transpiration

Cane Sawgrass Base Soil Grass
Tank 1 Tank 2 Tank 3 T ank 4
Inches Inches Inches Inches

1.43 * 1.20 2.67
1.02 1.12 2.87
1.64 2.08 4.34
3.48 2.79 3.54 6.80
5.55 3.22 4.43 5.24
5.94 4.86 4.56 I 4.86
6.45 5.42 4.94 7.28
5.36 6.60 4.74 5.95
3.87 5.43 3.78 4.38
3.56 4.25 1.89 3.44
2.76 4.86 2.76 2.13
2.70 4.06 0.93 1.95


43.76 35 .97 51.91


Open Pan
Inches

4.18 3.81 6.22 7.68
7.40 5.94 7.37
6.54 4.92 5.15
4.28 3.13


66.62


Mean Rainfall Temperature


Inches

1.91
4.04 2.40 1.96 6.39 18.61 6.09 5.33
5.84 1.65 9.17 1.18


64.57


F. 0

65.1 63.5 65.5 70.6 73.8 77.0 81.1 80.6 79.3 78.1 68.0 67.0


Note.-Cane (F31-1037) was cut Dec. 29, 1936. Yield of mill cane w is 28.4 tons per acre and 205 lbs. of 96o su,;ar per ton.
Sawgrass was set in Tank 2 on Mar. 3. By May 1 old sawgrass had died down and new sprouts appeared. Stand did not reach full size until Nov. Thereafter a good stand was maintained.
Soil in Tank 3 was Partially shaded during year by cane around tank.
Tank 4 was Planted to Alfalfa on Jan. 29. Stand died down by summer and was mostly grass and weeds during last half of year.
*No record.












TABLE 13.-EVAPORArrON AND TRANSPIRATION FROM TANKSt AND OPEN PAN FOR YEAR 1937, EVERGLADES EXPERIMENT STATION, BELLE GLADE, FLORIDA.


Ja Fe


Wind Av. Del
Month Motion Water
ITanks
________1,3&4
Miles

n.- ---- ----1 4076 1.28
b. - . --------- 4283 1.47


M ar.- ------Apr. M ay --- _---
June _. . July -------
Aug.- ------Sept._.
Oct.-----N ov . . . Dec.


Year ----


-1 4235
4037 3275
* 2978
2914 2853 2812
3345 4418 4275


43,501


th to
in Ft.
Tank Canet
2 Tank I
Inches

0.77 1.73
1.05 2.46
1.06 3.36
0.84 4.63
1.04 5.85
0.77 4.33
0.96 5.43
0.88 5.24
0.95 4.79
0.93 3.44
0.93 2.49
0.99 1.67


1.34 0.93 45.42


Evaporation and Transpiration


Sawgrass Tank 2
Inches

5.61
4.93 6.24 7.53
9.64 7.05 9.95 8.80 8.93 7.60
4.14 3.62


IRainfall i


Bare Soil Mulch Soill Open Tank 3 Tank 4 Pan
Inches Inches inches Inches

1.75 0.53 4.44 2.97
2.91 0.66 3.86 1.21
3.78 0.71 5.30 5.87
4.26 1.06 6.30 . 6.00
4.54 1.05 7.77 3.38
4.53 1.18 6.70 7.74
5.09) 2.05 16.66 7.65
4.99 1.48 16.02 7.89
4.38 1.39 5.58 8.35
.3.20 1.10 4.93 4.92
1.44 0.55 .3.76 2.08
1.41 0.43 3.12 0.38


84.04 42. 28 112.19 64.44 58.44


Mean
Temperature

F.0

70.8
64.7 66.1 70.0
74.0 78.3 79.7 80.6 78.9 73.8 67.1 63.2


72.3


Note.-Cane (F31-1037) was cut Dec. 17. Yield of cane was 20.0 tons per acre and 219 lbs. of 960 su-car per ton. Stand was poor probably due to wire worms. Sawgra s fully grown and shaded by cane around tank. Stand] Probably equal to average in Glades. Rare soil partially shaded by cane around tank. About 4 inches of cane leaves used fajw mulch on Tank 4.








TABLE 14.-EVAPORATION AND TRANSPIRATION FROM TANKS AND OPEN PAN FOR YEAR 1938, EVERGLADES EXPERIMENT STATION, BELLE GLADE, FLORIDA.

Wind Av. Depth to Evaporation and Transpiration inMean
Month Motion Water in Ft. Rainfall TemperaTanks Tank Cane Sawgrass Grass Mulch Soil Open ture
1, 3 & 4 2 Tank I Tank 2 Tank 3 Tank 4 Pan _ _ _J
Miles Inches Inches Inches Inches Inches Inches F.

Jan. -------- 4140 1.60 0.78 0.56 4.01 0.56 3.69 0.46 62.5
Feb. --.-----. 4685 1.45 0.90 0.62 4.17 2.87 0.59 4.22 1.14 65.4
Mar. 3833 1.43 1.02 0.73 6.49 4.93 0.43 5.85 1.87 68.9
Apr. . 4300 1.51 1.04 1.29 7.;2 5.27 0.46 6.78 0.32 69.8
May 3224 1.37 0.92 2.33 7.69 6.98 0.76 6.66 4.52 75.8
June -.-. 2913 1.39 0.90 3.93 7.59 7.26 1.11 6.50 5.44 77.6
July 3188 1.26 0.94 5.70 6.72 5.63 1.65 6.64 8.85 79.0
Aug . . . 3062 1.45 1.00 6.00 7.05 5.80 0.59 6.75 2.65 79.8
Sept. . . 2961 1.36 0.88 5.46 5.99 4.65 1.08 5.92 10.09 78.6
Oct . . 4220 1.43 0.95 3.45 5.09 4.34 0.78 5.34 2.78 72.5
Nov. . 3663 1.39 0.90 2.67 3.48 8.57 0.81 4.08 2.66 71.2
Dec. . 3554 1.50 0.96 2.29 2.25 2.69 0.28 3.36 0.21 63.7


Year 43,743 1.43 0,93 35.03 67.85 53.99 9.10 65.79 40.99 72.1

Note-Cane iF31-436) was planted last week of Dec., 1937, and cut Jan. 3. 1939. Yield was 37.4 tons per acre. Both Cane Tank I and Mulch Tank I were covered with a heavy layer of cane trash during the year. The difference between the total evaporations of the 2 tanks or 25.93 inches is rouhly the transpiration loss through the cane. This amounted to 78.4 pounds of water per pound of mill cane, and 763 pounds of water per y/ pound of 96- sugar.
The sawgrass in Tank 2 was surrounded by cane for a windbreak. The stand of sawgrass was below normal during the last half of year. Tank
3 was planted to Bahia grass in January. The grass was not cut during the year.
-No record.





Florida Agricultural Experiment Station


by Mr. F. D. Stevens, sugarcane agronomist, Everglades Station, showed that the transpiration amounted to 78.4 pounds of water per pound of mill cane, and 763 pounds of water per pound of 96' sugar.
The four-year evaporation record from the uncropped and unmulched tank showed an average loss of 40 inches per year. The difference between the several years is doubtless due, in part, to variation in the amount of shading and probably also to variation in frequency of rainfall. When the surface soil is kept wet by frequent rains evaporation increases.
On January 29, 1936, one of the tanks was planted to alfalfa but the stand died down by summer and was mainly grass and weeds during the last half of the year. Evaporation and transpiration for 11 months exclusive of January totaled 49.2 inches. On January 3, 1938, a tank was planted to Bahia grass. The grass grew well and was not cut during the year. Cane was planted around the tank as a windbreak. The water table averaged 1.4 feet. Evaporation and transpiration for 11 months, exclusive of January, were 54.0 inches. The estimated total for a full year was 57 inches. It is evident that the losses from grass land are very high.
To secure data with which to estimate the evaporation from the sawgrass land of the Everglades, the sawgrass plants from an area of 4x12 feet were transplanted in a tank of the same area in March, 1936. By May I the old sawgrass had died down and new sprouts appeared. These did not reach full size until November. Through the year 1937 the stand was equal to that on the land from which the plants were taken. Cane was planted around the sawgrass tank to serve as a windbreak. The water table averaged nearly a foot in depth. Evaporation and transpiration for the year 1937 amounted to 84 inches.
During the last half of the year 1938 the sawgrass deteriorated to a considerable extent, but was probably somewhat better than the average stand on the virgin areas of the Everg'ades. Evaporation and transpiration for the year amounted to almost 68 inches.
There are very few data on average depth of water table in the sawgrass area of the Everglades. The water table may vary from surface to a depth of four feet or more. It probably averages about two feet. Annual evaporation from the Everglades would be somewhat less than that from the tank, due to the deeper water table and also a little better protection from wind.





Water Control in the Soils of the Everglades


After making some allowance for these differences it is estimated that the mean annual evaporation from the sawgrass lands averages about 60 inches. As this is substantially more than the average rainfall of approximately 53 inches, the results indicate that run-off and seepage from outside areas are a considerable factor in maintaining the water table beneath the peat lands of the Everglades.
Evaporation records from a standard Weather Bureau open pan have been kept by the Everglades Station since 1924. The records for the years 1934 to 1938 show a five-year average loss of 66.54 inches. This evaporation is considerably higher than that from a large open body of water such as a lake. Experiments, in the arid West, conducted by the Irrigation Division of the Soil Conservation Service, USDA,6 indicated that the evaporation from large bodies of open water is approximately 70 percent of that from a standard Weather Bureau open pan. If this ratio also holds for the humid region, the mean annual evaporation from a large body of water such as Lake Okeechobee would approximate 47 inches.

TEMPERATURE
The mean annual temperature at the Everglades Station for the five-year period of 1934 to 1938 was 72.1' F. August was the warmest month with an average of 80.2' and December was the coldest with an average of 62.80 for the five-year period. The Everglades Station has kept a record of temperatures since July, 1924. The maximum of 1001 was reached three times in July, 1931. The minimum recorded at a height of four feet above the ground was 25' on January 15, 1926, and again on December 13, 1934. The record shows that temperatures of 320 or less were experienced 12 times in December, 11 times in January, three times in February and six times in March, during a period of 14 years.
The Everglades Station has kept a record of minimum temperatures from a point near the Hillsboro locks west of Belle Glade to Twenty Mile Bend on the West Palm Beach Canal. The thermometers are located near State Highway 25 and are set in boxes about four feet above the ground. Table 15 shows the readings at the several stations for periods when the minimum at the Experiment Station was 380 or less. Readings at the
' Rohwer, Carl. Evaporation from free water surfaces. U. S. Dept. Agr. Tech. Bul. 271. 1931.






Florida Agricultural Experiment Station


Experiment Station, 4.3 miles below the Hillsboro lock, are taken each day, but those at the other stations were usually read once a week during the cold portion of the year. The readings are

TABLE 15.-MiNimum TEMPERATURES ALONG HIGHWAY No. 25 FOR PERIODS
WHEN MINIMUM WAS 38' F. ou LESS AT THE EVERGLADES EXPERIMENT
STATION FROM DECEMBER, 1929, TO MARCH, 1938.

Date Distance from Hillsboro Lock No. 1 in Miles
0.2 1.3 1 2.6 4.3 8.4** 13.5** 121.5*


12/26/29 . 38.0 34.0 I32.5 33.5 27.0 28.0 27.0
1/31/30 . 38.O-*j 38.0- 35.0- 36.0- - - 31.03/5/30.---30.0 28.0 30.0 30.0 26.5 26.0 21.0
11/26/30. 37.0 36.0 36.0 35.0 34,5 32.0 33.0
12/10/30 -- ---31.0 28.5 29.0 28.5 23.0 23.0 23.0
12/15/30 --. 38.5- 34.0- 34.0- 35.5- 30.0- 28.512/24/30. 41.0- 39.0- 40.*0- 34.0- - 32.0- 31.012/28/30 .i38.5 35.0 35.0 35.0 32.0 32.0 30.0
1/7/31.---35.0 31.5 30.0 29.0 23.5 22.5 20.5
1/15/31 ------ . 38.5- 38.0- 37.5- 36.5- 35.0- - 35.01/22/31 . 39.0 38.0 37.0 32.0 32.0 34.0 31.0
3/5/31 -------- . 34.5 33.0 33.0 32.0 27.0 29.5 27.5
3/12/31 .45.0 44.0 41.0 30.0 34.0 35.0 35.0
4/8/31 . 39.0 35.5 32.5 33.0 28.0 31.0 28.0 10/10/32 .43.0 37.0 37.5 37.0 37.0 32.0 30.0
3/14/32.--35.0 30.0 30.0 32.0 27.0 28.0 25.0
1/29/33 _.32.5 28.5 30.0 34.0 28.5 32.0 28.0
2/6/33 . .36.0 31.0 34.0 35.0 28.0 30.0 31.0
3/4/33 ------- 34.0 29.0 31.5 34.0 24.5 29.0 27.0
1/11/34 ----- - 45.0 37.0 35.5 37.0 34.5 33.0 28.0
1/31/34 . 42.0 38.0 35.0 38.0 37.0 31.0 31.0
2/3/34 -------41.0 34.5 37.0 36.0 26.0 27.0 26.5
3 23 . - 32.0- 34.0- 3. 33.0- 30.0- 29.012/13/34 ----- 26.5 27.0 23.0 25.0 18.0 13.0 13.0
12/14/34 --- 40.0 35.'0 36.0 37.0 30.0 29.0 25.0
1/24/35 . -- 41.0 39.5 38.0 36.0 32.0 30.0 28.0
2/5/35 ----. . 32.0 30.5 30.0 31.0 21.5 27.0 28.0
2/21/35 -- - --- 38.5 37.0 35.0 38.0 30.0 30.0 27.0
2/28/35 . 39.5- 39.0- - 37.0- 31.0- 25.0- 26.012/1/35 .30.0 30.0 31.5 34.0 26.0 27.0 26.5
12/19/35 .35.5 32.0 32.0 34.0 27.0 27.5 28.0
12/21/35 ------30.0 30.0 30.0 30.0 25.0 24.5 24.5
2/1/36 . 38.0 37.5 36.0 36.0 33.0 30.5 31.0
2/11/36 . 36.0 36.0 35.0 37.0 33.0 28.0 33.0
3/19136 ------- 37.0-I 36.0- 36.0- 136.0- 33.0- 36.0-
3/22/36 ------- 34.0 33.5 I34.0 35.0 29.0 35.0 37.0
11/28/36.-141.0 -- -- 34.0- - 36.0- 36.02/6/37.33.0- - 33.5- 37.0- 27.0- 30.0- 30.011/21/37 .40.0- 40.0- 36.0- 36.0- 34.012/7/37. --.32.0- 32.0- 29.0- 31.0- 28.0- -
1/28/38 ------- 30.0- 30.0- 28.0- 32.0- 24.5- - 26.02/26/38 -------. 39.0- 37.0- 38.0- 34.0Average .36.5 33.7 33.3 33.6 28.8 28.8 27.7

*Readings marked (-) are not included in avera es,
"0Locations at Miles 8.4; 1.3.5; and 21.5 were in areas of virgin sawgrass.





Water Cont?-ol iv the Soils of the Everglades


the minimums for the period covered and when the minimum for the period was 380 or less at the Experiment Station the corresponding readings at the several stations are shown as of the same date. For this reason all readings of 38c or less at the Experiment Station are not shown, for if the minimum were 380 for one day of the period and 35" for another day only the lowest reading would be shown.
The table shows the change in minimum temperatures with distance from Lake Okeechobee. The stations at 0.2, 1.3, 2.6, and 4.3, miles from the lock are on cultivated ground while those at 8.4, 14.0, and 21.5 miles from the lock are on virgin land. The lock is 1.3 miles from the new lake levee. The data indicate that low temperatures at the lock average nearly 30 warmer than those at the Experiment Station (4.3 mi.) and nearly 9' warmer than those at Twenty Mile Bend (21.5 miles). There is reason to believe that these low temperatures in the virgin land would be 3 or 40 higher if the land were in cultivation. The very loose top soil and mulch of leaves and trash on the virgin land acts as an insulating cover which retards the flow of heat from the wet soil beneath to the air above.
The Shawano Plantation is located on the Hillsboro Canal about 11 miles southeast of the Everglades Experiment Station. A record of temperatures on the cultivated areas in that location is available since January 1, 1929. A comparison of the minimum readings of 38' or less at the Experiment Station with those at Shawano shows those of the latter station to average 1.10 lower than at the Experiment Station. However, the difference is somewhat greater when the comparison is confined to very low temperatures. From January, 1929, to March, 1938, a tabulation of temperatures, when the minimum was 320 or less at either of these stations, showed an average difference of 2", while the minimum readings on cultivated land near Gladeview (13.5 miles) showed a difference of 4.8'. As the station near Gladeview is about the same distance from Lake Okeechobee as that at Shawano, the comparison indicates that temperatures of 380 or less will average from 3 to 40 higher after the virgin land is prIaced in cultivation.
On March 14, 1932, a minimum temperature of 9" was recorded on a thermograph located one foot above ground on virgin sawgrass land at the Shawano plantation. The water table was very low in the soil at that time and the Glades very dry and





Florida Agricultural Experiment Station


covered with a deep mantle of dead weeds and sawgrass from earlier frosts.
On December 13, 1934, two readings of 13' were recorded on virgin land (see Table 15). One was 13.5 and the other 21.5 miles east of the Hillsboro locks along State Highway 25. A minimum thermometer set by the Everglades Station 15 miles below South Bay and 600 feet west of the North New River Canal on virgin land recorded a low of 14.00 on or about March 5, 1930.
These records indicate that very low temperatures occasionally occur in the virgin areas east and south of Lake Okeechobee. It is probable that higher minimum temperatures would result if the water tables in the outer areas could be held near or above the surface.

WATER CONTROL BY PUMPING
The early drainage of the peat lands around Lake Okeechobee depended on gravity systems discharging into the large outlet canals, which were never entirely completed. Due to the flat topography the ditch gradients are only a few inches per mile and hence the water movement is very slow. The subsidence following original drainage further reduced the effectiveness of the gravity systems. To improve their drainage nearly all the sub-districts in the northern Everglades have installed large pumps, and many farmers also have installed private pumps to increase the effectiveness of their water control. The first large pumping plants were built in 1925. As most of the pumps are reversible, water as needed may be pumped into the areas served and thus control the water levels during dry periods. The majority of the large plants are located near Lake Okeechobee and discharge into the lake; however, a few are located farther back on the large canals and the water from these may run either into the lake or down the canals, depending on the relative lake and canal stages. The amount of pumping varies widely from year to year, depending largely on the amount of rainfall. There is little pumping from November 1 to June 1, the dry portion of the year.
Nearly all the large plants use the screw type pumps with a capacity of from 30,000 to 60,000 gallons per minute, but in recent years a few large vertical turbine pumps of 30,000 to 40,000-gallon capacity have been installed. The large screw pumps are driven by heavy duty diesel engines of from 80 to





Water Control in the Soils of the Everglades 39

180 horsepower and one large vertical turbine pump uses a 125 horsepower electric motor. This particular pump is operated under an off-peak contract and the cost of power has averaged approximately 1.8 cents per k.w.h.
The drainage districts of the northern Everglades have installed pumping plants with a total rated horsepower of approximately 5,500 and a total capacity of approximately 4,200 second feet. The average static lift is probably close to four feet and the maximum lift has seldom reached eight feet. The discharge capacity of most of the large pumping plants is approximately one inch in 24 hours over the area served, but a few have capacities of 1.5 inches. In addition to the large plants there are a number of small plants serving areas of 80 to 640 acres. These are usually privately owned. Many of them are located within the areas served by the district pumps and provide additional facilities for controlling the water table on individual farms. The capacities of these smaller pumps usually range from 1.5 to 3 inches. Approximately 100,000 acres in the northern Everglades are served by pumps and about 85 percent of this acreage is in agricultural use.
Approximately 60 percent of the rainfall near Lake Okeechobee occurs during the four-month period of June to September, and by far the greater part of the pumping is done during these months. During the late winter and spring months a small amount of water is pumped into the districts to raise the water table. This will probably not average over six inches and will seldom exceed 12 inches in the driest years. A comparison of the amount pumped with the estimated difference between rainfall and evaporation indicates that seepage accounts for a large portion of the water pumped from a drainage area.

DESCRIPTION OF PUMPING PLANTS
During the six-year period of 1933 to 1938, inclusive, pumping records have been kept on four large plants near Canal Point and on one small plant at the Everglades Station. The locations of these plants are shown in Figure 1. The four large plants located in the Pelican Lake and Pahokee drainage districts are fairly typical of the larger plants around Lake Okeechobee. They have a discharge capacity of one inch in 24 hours and may be reversed to supply irrigation water when needed. The cultivated acreage is largely planted to sugarcane, but a substantial amount is used for truck crops, All four plants pump directly into the





Florida Agricultural Experiment Station


West Palm Beach Canal and the amount of pumping is considerably affected by the canal stage. The small plant at the Everglades Station near Belle Glade discharges directly into the Hillsboro Canal. This area served is planted to experimental crops of cane, truck and grasses. A larger amount of pumping is done through the summer than is usual on other land. Figure 6 shows a typical pumping plant of the northern Everglades.




A














Fig. 6.-A typical large pumping plant of the northern Everglades. Such plants contain from one to three pumps of approximately 56,000 gallons capacity each.

Pelican Lake Unit No. I.-The two engines are each 80 horsepower, vertical, two-cylinder, type Y, diesels, made by FairbanksMorse and Company, and are directly connected to the pumps. The full speed is 300 revolutions per minute, but this can be varied by special adjustments. The two pumps are each 42-inch Wood-screw type, with a rated capacity of 30,000 gallons per minute. The pump house is made of corrugated metal on timber framework and is set on a concrete foundation. The total cost of the plant was $55,000. Pumping operations were started in 1925.
Fuel oil consumption during the six-year period has averaged 1.14 gallons per acre-foot pumped, and 5.2 gallons per pump-hour of operation. The static lift has averaged 3.5 feet and the maximum lift was 7.1 feet. The plant-days of operation during a year has averaged 68.3. As one or more pumps in a given plant





Water Control in the Soils of the Everglades


may be operated during the day, a plant-day is determined by adding together the total days of operation of each pump during the year and dividing the result by the number of pumps.
Pelican Lake Unit No. 2-This plant is similar to Pelican Lake Unit No. 1. The total cost of the plant was $51,000. Pumping operations were started in July, 1929.
Fuel oil consumption during the six-year period has averaged 1.05 gallons per acre-foot pumped and 5.2 gallons per pumphour of operation. The static lift has averaged 3.9 feet and the maximum lift was 7.5 feet. The plant-days of operation during a year has averaged 44.2.
Figure 7 shows the record of pump operations at the two Pelican Lake plants for the year 1934. Similar charts have been prepared for the other five years of record. Copies of these

I' I ApI,


-A


Fig. 7.-Record of pumping plant operation at Pelican Lake Drainage District, Florida, 1934. Total water pumped for drainage: Unit No. 1, 23,764.2 acre-feet (7.03 feet on 3,379 acres); Unit No. 2, 14,287.2 acre-feet (5.01 feet on 2,853 acres). Total rainfall (both units), 69.78 inches Or 5.82 feet. Total fuel oil used: Unit No. I ' 26,300 gallons; Unit No. 2, 15,985 gallons. Average lift of pumps: Unit No. 1, 3.3 feet; Unit No. 2, 4.3 feet.





Florida Agricultural Experiment Station


may be obtained from the Soil Conservation Service, U. S. Dept. of Agriculture, Washington, D. C. Total amount of pumping, depth over the drainage area, rainfall, fuel oil used, and average lifts are shown for each plant. During the year 1934 Unit No. I pumped approximately seven feet from the drainage area, and Unit No. 2 pumped five feet. This difference is mainly due to the heavy seepage into the area of Unit No. 1 from undrained lands to the east. There is a large area of virgin land between the St. Lucie and West Palm Beach canals, much of which drains to the south. A high water table in lands outside of a pumped area materially increases the amount of pumping. A high stage in the West Palm Beach Canal also increased the pumping in each of these units, due likewise to seepage which reaches the pumped area through the porous limestone and sand beneath the peat. This seepage probably has little effect on the maximum rate of pumping, but prolongs the pumping period.
The rainfall at Azuear, located between the two Pelican Lake units, will probably differ little from the average over the two drainage areas. For the years 1933 to 1938, inclusive, the annual amounts were 61.1, 69.8, 52.5, 57.8, 55.7 and 39.3 inches, respectively. The average was 56.0 inches.
If the rainfall, evaporation and depth pumped for a given area are known, an approximate estimate may be made of the seepage during a year. Azucar is located near the center of Unit 2 of the Pelican Lake District and all land is within two miles of the rain gage. Nearly all the land is in sugarcane. Records at the Everg'ades Station indicate that the annual evaporation from such an area approximates 3.5 feet. The rainfall for 1936 was 4.82 feet, which is close to normal, and the depth pumped was 4.09 feet. These data indicate that the seepage inflow was equivalent to a depth of 2.77 feet. The average annual seepage depth for the six-year period was 2.5 feet. A large area under similar conditions would show a smaller depth of seepage.
East Pahokee Unit No. I.-The two engines are each 180 horsepower, vertical, three-cylinder, type Y, diesels, made by Fairbanks-Morse and Company, and are directly connected to the pumps. The full speed is 257 revolutions per minute and this can be readily reduced by a speed control mechanism on each engine, so that a fairly constant canal stage can be maintained at the pump intake. The two pumps are each a 54-inch Woodscrew type with a rated capacity of 60,000 gallons per minute.





Water Control in the Soils of the Everglades


The pump house is made of corrugated metal on steel framework, and is set on a concrete foundation. The total cost of the plant was S75,000. Pumping operations were started in November, 1929.
Fuel oil consumption during the six-year period has averaged 0.96 gallons per acre-foot pumped, and 6.8 gallons per pump-hour of operation. The static lift averaged 4.4 feet and the maximum lift was 7.5 feet. The average lif t for the year 1938 was 2.9 feet. This low lift was due to the fact that the West Palm Beach Canal was at a very low stage during the year and also because there was considerable pumping for irrigation in December when there was little or no lift. Some water was siphoned into the district through the pumps with the engines disconnected. The plant days of operation during the six-year period has averaged 39.5.
East Pahokee Unit No. 2-The equipment of this plant is similar to that of East Pahokee Unit No. 1, except that there are three engines and pumps instead of two. The total cost of the plant was $105,000. Pump operations were started in January, 1930.
Fuel oil consumption during the six-year period averaged 0.91 gallons per acre-foot pumped and 7.7 gallons per pump-bour of operations. The static lift averaged 4.1 and the maximum lift was 7.6 f eet. The average lift for the year 1938 was 2.3 feet. This low lift was due to the low stage of the West Palm Beach Canal and also to the large amount of pumping for irrigation in April, May and December, when the lift was very low. The amount pumped for drainage in 1938 was 7,757 acre-feet and that pumped for irrigation was 11,039 acre-feet. The plant-days of operation during the six-year period averaged 40.0.
Figure 8 shows the record of pump operations at the two East Pahokee plants for the year 1934. Similar charts have been prepared for the other five years of record. Copies of these may be obtained from the Soil Conservation Service, Washington, D. C. The amount pumped, depth over the drainage area, rainfall, fuel oil used, and average lift are shown for each plant. The records indicate that the stage in the West Palm Beach Canal has a substantial effect on the amount of pumping. This is particularly evident when a comparison is made of the pumping in August and October, 1935.
The drainage areas of these two units are not completely separated, as a ditch at the west end of the district may carry





44 Florida Agricultural Experiment Station

water to either unit. The six-year record for Unit I shows an average annual depth pumped for drainage of 2.26 feet and for irrigation of 0.004 feet. The record for Unit 2 shows 2.25 feet pumped for drainage and 0.30 feet for irrigation. The two units combined show 2.26 feet pumped for drainage and 0.20 feet for irrigation. In 1938, the driest year of record, Unit 2 pumped 0.82 feet for drainage and 1.16 feet for irrigation. The rainfall near the center of Unit 1 for the years 1933 to 1938, inclusive, was 64.57, 66.20, 49.36, 57.45, 53.84 and 33.72 inches, respectively. The average was 54.19 inches. There was no rain gage in Unit 2, but the rainfall will probably differ little from the
above.
A comparison of the depth pumped by Pelican Lake Unit No. 1

A g. S 0 f. 0, t. N- Dec.

e

ec 14






0
:Ac e: , q76.4 4 11
700

> 400 J
300 - 4- L



3'1



411 IS --- h
3- 1. 41 .05 _2

Fig. 8-Record of pump operation at East Pahokee Drainage District,
Florida, 1934. Total water pumped for drainage: Unit No. 1, 16,588.0 acrefeet (2.86 feet on 5,798 acres); Unit No. 2, 30,270.8 acre-feet (3.20 feet on 9,478 acres). Total rainfall (both units), 66.20 inches or 5.52 feet. Total fuel oil used: Unit No. 1, 17,500 gallons; Unit No. 2, 32,087 gallons.
Average lift of pumps: Unit No. 1, 4.7 feet; Unit No. 2, 4.7 feet.





Water Control iv the Soils of the Everglades


with that of East Pahokee Unit No. 1 shows that the six-year average for the former plant was almost twice that of the latter plant. The effect of a high water table outside of a pumped area is here clearly shown. Pelican Lake Unit No. 1 abuts on virgin land to the east in which the water table is usually high due to seepage from higher lands. On the west it abuts on the sandy ridge along Lake Okeechobee whose average stage is as high as the lands in the pumped area. The East Pahokee Unit No. I adjoins pumped lands to the north, south and west. Both areas have about the same frontage on the West Palm Beach Canal.
Everglades Experiment Station Plant.-The electric motor is a four-speed Westinghouse, type C. S. induction model. It is rated from 4.2 to 30 horsepower, depending on the speed used, and is connected to the pump by a set of short V-belts. The four speeds are 445, 590, 890 and 1,180 revolutions per minute. However, nearly all the operation has been at the third speed of 890 revolutions per minute. A small amount of pumping has been done with an oil engine, but the energy so used has been estimated in equivalent kilowatt hours and added to the totals shown for the electric motor.
The pump is a 24-inch vertical turbine rated at 10,000 gallons per minute at high speed, and is so built that water can be pumped either in or out of the area, served by the simple operation of four vertical slides. It was made by the Couch Manufacturing Company and has four speeds of 217, 292, 442 and 574 revolutions per minute. The pump is started and stopped by an automatic float in the intake ditch, and requires little attention during operation. The pump house is made of corrugated metal on steel framework and is set on a concrete foundation. The total cost of the plant was approximately $3,400. It began operating in July, 1931.
The electric power used is three-phase, 60-cycle, 220-volt current. The cost of power up to July 1, 1936, was based on a charge of $4.00 per "contract" horsepower for the first 25 "contract" units per month for four months in each yearly period; $3.00 per horsepower for all additional "contract" horsepower per month for four months in each year; and 3 cents per kilowatt-hour for all energy used per month. Since July 1, 1936, the plant was operated under a new contract, but the cost of power was reduced only a very small amount, although the basis of calculating the cost was changed.





46 Florida Agricultural Experiment Station

The record covers a six-year period. During the first three years the area drained was 162 acres, but after that period an additional 40 acres was added to the farm. This new land may drain either to the South Florida Conservancy District pump or to the Experiment Station pump. It is estimated that approximately 180 acres are now served by the Experiment Station pump and the cost estimates for the last three years are based on that area. The annual cost of electric power during the six-year period has averaged $3.90 per acre served and 6.1 cents per k.w.h. used. The average period of operation has been 49 days per year. The annual rainfall for the six-year period varied from 65.3 to 41.0 inches and averaged 56.7 inches. The static lift has averaged 2.1 feet and the maximum lift was 4.2 feet. The record


'EoPe~oons'fo d-h3 04 P-


11 -


140 lo
Il.ok



25


-36 0 .2 11.4 11 -1t h 0 0. 0 723


fL


Fig. 9.-Record of pump operation at Everglades Experiment Station, Florida, 1934. Total water pumped for drainage, 1,411.1 acre-feet (8.71 feet on 162 acres). Total water pumped for irrigation, 87.7 acre-feet (0.54 feet on 162 acres). Total time of pumping, 1,338 hours (55.8 days). Total energy used, 12,665 k.w.h. Total cost of electric power, $780. Average lift of pump, 2.32 feet.






Water Control in the Soils of the Everglades


for the six years shows an average annual depth of 6.9 feet pumped out for drainage and 0.65 feet pumped in for irrigation. Figure 9 shows the record of pump operation at the Everglades Station for the year 1934. Similar charts have been prepared for the other years. Copies of these may be obtained from the Soil Conservation Service, Washington, D. C. The amount pumped, depth over the drainage area, kilowatt hours used, rainfall, and stages of the Hillsboro Canal are shown for each year.
The charts show that the amount of pumping is increased when the Hillsboro Canal is at a high stage. During May, 1936, with a rainfall of 6.4 inches and an average canal stage of 12.9 feet, only 12 acre-feet were pumped for drainage while in July with a rainfall of 6.1 inches and a canal stage 3.8 f eet higher, 407 acre-feet were pumped. This increase indicates the effect of a high water table outside a cultivated area on the amount of pumping. This, however, is an extreme case, as the variation in outside water table is seldom so wide. The Experiment Station area has a frontage of over a mile on the Hillsboro Canal and due to the use of the land for experimental purposes more pumping is done in the summer than is the case with ordinary farm land. These conditions account for the large annual amount of pumping. A small quantity of water is run into and out of the area by gravity, but it is estimated that the quantities will about balance. From evaporation experiments with sugarcane, grass, bare soil, and open water it is estimated that the annual evaporation from the Experiment Station farm will approximate 3.5 feet. This figure, used with the amount pumped and the rainfall, indicates a seepage inflow varying from two to seven feet per year and averaging five feet. As previously stated, the seepage will depend on the water table in surrounding lands and on the stage of the Hillsboro Canal.

FIXED AND OPERATING COSTS OF PUMPING
The installation costs and fixed charges for each pumping plant are shown in Table 16. The term "fixed charges" as used in this report includes the annual interest on the capital invested and the annual depreciation charge. The interest on invested capital is figured at 6 percent. The depreciation charge has been computed by the sinking fund method and the annual charge is such an amount that, invested at 4 percent compound interest, the sum of the payments and the interest will equal the cost of the building and equipment at the end of their estimated life.







Florida Agricultural Experiment Station

TABLE 16.-FIXED CHARGES OF PUMPING PLANTS.

Cost ___Intere
Plant Engne Depre- at 6
Building and Total ciation Perce:
___ ___ Pumps

can LakeI
iA1~- 29 1A 12"N 1Q(7rf tr, on qt A7 R3 0


Pelican LakeI Unit No. 2

East Pahokee Unit No. 1

East Pahokee Unit No. 2

Everglades Experiment Station I


20,250 130,750


32,000


40,000 1,900


43,000


51,000 75,000


65,000 105,000 1.500 3,400


1,713 2,519 3,526



114


st nt


3,060


4,500 6,300



204


As both the building and equipment in the plants studied are of a very durable type, the life of the entire plant has been estimated at 20 years. The Wood-screw type of pumps have all moving parts above water and the heavy duty diesel engines are of a type that has been in use for 20 years in other fields. The foundations and floors of pump houses are concrete and the buildings are covered with corrugated sheet metal and all but one has steel framework.
The costs of fuel oil or electricity, lubricating oil and labor are shown in Tables 17a, 17b and 17c. The unit costs per acre served and per acre-foot pumped are also shown. The period of operation is expressed in plant-days. As the oil engine plants have two or more pumps and all or part of the units may be in operation at a particular time, the number of days on which some pumping was done was greater than the plant-days shown. The plant-days were determined by reducing the total pump-hours to 24-hour days and dividing the result by the number of pumps.
The Wood-screw pumps were rated with a Pitot tube and current meter. A record of the lifts and speeds was kept. The Experiment Station pump was rated with a current meter but during the last two years a submerged orifice has been used and the discharge computed from a continuous record of the head on the orifice. The cost of fuel oil delivered at the plants has ranged from 6.5 to 7.0 cents per gallon. The cost of lubricating oil and gasoline includes the gasoline used in the lighting plant, in the compressor engine and for the truck used in supervising the


Peli


Total Fixed Charges


j$5,147


4,773 7,019 9,826 318


I


I





TABLE 17A.-COSTS OF FUEL OIL, LUBRICATING OIL, AND LABOR AT PUMPING PLANTS.
ICosts for Year Size Period of I Costs for Year
Plant Year of Area Opera- Water Per Per
Engine Served tion Pumped Fuel Oil Lub. Oil Labor Total Acre Acre-Foot
__ and Gas Served Pumned
H. P. Acres Plant Acre-FeetI Dollars Dollars Dollars Dollars Dollars Dollars "N Days 1 I"
Pelican Lake 1933 10GO 3,379 82.8 19,181 1,384 298 1,510 3,192 0.94 0.17

Unit No. 1 1934 160 3,379 103.4 23,764 1,710 310 1,910 3,930 1.16 0.17
1935 160 3,;7! 48.6 11,105 764 175 1,250 2,189 0.65 0.20 C

1936 160 3,379 62.8 14,174 1,089 220 1,535 2,844 0.84 0.20

1937 160 ,379 87.6 16,024 1,485 255 1,603 3,343 0.99 0.21

1938 160 3,379 24.4 4,904 398 132 788 1,318 0.39 0.27

Average 160 3,379 68.3 14,859 1.138 232 1,433 2,803 0.83 0.19


Pelican Lake 1933 160 2,85,3 41.5 9,858 718 159 1,062 1,939 0.68 0.20

Unit No. 2 1934 160 2,853 61.5 14,287 1.037 235 1,315 2,587 0.91 0.18

1935 1 0 2.853 30.6 7,488 49i2 17 1,143 1,752 0.61 0.23

1936 1 0 2,853 47.8 11,667 784 172 1,295 2,251 0.79 0.19
1937 160 2,853 65.6 15,089 1,124 205 1,313 2,642 0.93 0.18

1938 160 2,853 18.1 4,232 274 120 78 1,072 0.38 0.25

Average 160 2,853 44.2 10,437 738 168 1,134 2,041 0.72 0.20








TABLE 17B.-COSTS OF FUEL OIL, LUBRICATING OIL, AND LABOR AT PUMPING PLANTS.

I Costs for Year
Size IPerio ofI_ _ _ _ _ _
Plant Year of Area Op era- Water I-T - I Per Per
I Engine Served tion Pumped Fuel Oil Lub. Oil Labor Total Acre Acre-Foot
I____ and Gas Served Pumped
H. P. Acres jPlant Acre-Feet Dollars Dollars iDollars Dollars Dollars Dollars
Days
East Pahokee 1933 360 5,798 48.2 15,607 1,070 222 971 2,263 0.39 0.14

Unit No. 1 1934 360 5,798 55.6 16,588 1,138 256 1,160 2,554 0.44 0.15

1935 360 15,798 37.4 11,210 666 172 930 1,768 0.30 0.16

1936 360 5,798 33.5 12,627 792 160 1,276 2,228 0.38 0.18

1937 360 5,798 39.2 15,556 1,001 200 1,188 2,389 0.41 0.15

1938 360 5,798 23.1 8,414 503 155 833 1,491 0.26 0.18

Average 360 5,798 39.5 13,334 832 194 1,060 2,116 0.36 0.16
_________ __t3 East Pahokee 1933 540 9,478 49.7 28,609 1,970 277 1,212 3,459 0.36 0.12

Unit No. 2 1934 540 9,478 54.6 30,271 2,086 305 1,430 3,821 0.40 0.13

1935 540 9,478 35.3 21,385 1,184 197 1,101 2,482 0.26 0.12

1936 540 9,478 41.7 26,071 1,430 286 1,459 3,175 0.333 0.12 (

1937 I 540 9,478 31.1 19,747 1,215 243 1,034 2,492 0.26 0.13

1938 540 9,478 27.6 18,796 964 201 923 2,088 0.22 0.11

Average 540 9,478 40.0 24,146 1,475 252 1,193 2,920 0.31 0.12












TABLE 17c.-COSTS OF ELECTRIC POWER AND L\IIOR AT EVERGLADES EXPERIMENT STATION PUMP.


Plant Year


Everglades 1933

Exp. Station 1934 1935 1936 1937 1938 Average


Size of
Motor


H. P.
30 30 30 30 30 30 30


Area Served

Acres

162 162 162

180-

180!:

180i

171


*Period of


Operation Plant Days 72.4 55.8 51.0 60.9 42.1 11.7 49.0


Water
Pumped Electric
Power
Acre-Feet Dollars

1,670 785

1,499 780

1,349 750

1,822 8:36

1,076 623

329 220

1,291 636


Ccsts for Year
Per
Lub. Oil Labor Total Acre
Served
Dollars Dollars Dollars Dollars

75 860 5.31

75 855 5.28

75 825 5.09

75 911 5.06

75 698 3.88

75 295 1.64

75 741 4.33


Per
Acre-Foot SPumped


Dollars
0.51 0.57 0.61 0.50 0.65 0.90 0.57


Period of






Florida Agiicultural Experiment Station


plants. No cost is shown for lubricating oil at the Experiment Station plant as the amount used is very small and no record is kept.
The labor costs at the four oil engine plants include the wages of attendants and help used in cleaning screens and also that part of the superintendent's salary chargeable to supervision of these plants. The Experiment Station plant requires no regular attendant, so the labor item was estimated.
Tables 18a, 18b and 18c show the total operating costs, including fixed charges. The fixed charges are taken from Table 16. The annual maintenance costs have been estimated at 1 percent of the total investment in the plants. It is probable that $1 per horsepower per year would easily cover the engine repairs. The pumps and buildings require very little maintenance. The records available are not sufficient to determine maintenance costs, but 1 percent is believed to be ample. No insurance is carried on the plants, and no taxes were included in the estimates of pumping costs. The total costs are also shown as unit costs per acre served, per acre-foot pumped and per acre-foot lifted one foot.
Average costs as shown on the tables are based on the full six-year period and hence may not be the same as the average of the separate years. The costs per acre-foot pumped by Pelican Lake Unit 1 is less than that of Unit 2, due to the fact that more water is pumped by Unit 1. The costs, including fixed charges, however, do not vary much on the acre-served basis, being $2.52 for the one and $2.57 f or the other. The levees of Unit I are often subject to greater pressure than those of Unit 2, due to high water on the outside, hence the ditches usually are not pumped as low as those of Unit 2 and the average lift is
0.4 foot less.
The costs for East Pahokee Unit 1 are higher than those of Unit 2. However, the tables show that the average lift is greater for the first unit and the total depth pumped is less. Also the cost of the plant in relation to the acreage served is greater. The costs, including fixed charges, averaged $1.70 per acre for Unit I and $1.45 for Unit 2. These costs are considerably under those shown for the Pelican Lake plants, but it should be noted that the average depths of water pumped are considerably less, and the cost of these plants in relation to the acreage served is lower. The Pelican Lake plants are also less efficient than the East Pahokee plants.






TABLE 18A.-TOTAL OPERATING COSTS OF PUMPING PLANTS, INCLUDING FIXED CHARGES.

Costs for Year
Av. Water Area I Fixed Main- Oils &
Plant Year Static Pumped Served Charges tenance Labor Total Per Acre PerAc.Ft. PerAc. Ft.
Lift I I Amount Served Pumped Liftedlft.
Feet 'Acre-Feet Acres Dollars Dollars Dollars Dollars I Doliars Dollars Dollars I I


3,379 3,379 3,379 3,379 3,379 3,379 3,379


2,853 2,853 2,853


Pelican Lake Unit No. 1








Average Pelican Lake

Unit No. 2


3,192 8,889 2.63
3,930 9,627 2.85

2,189 7,886 2.33

2,844 8.541 2.53

3,343 9,040 2.68 1,318 7,015 2.08

2,803 8,500 2.52


19,181 2:3,764

11,105 14,174 16,024 4,904 14,859


i 0.46
0.41 0.71

0.60 0.56 1.43 0.57


1933 1934 1935 1936 1937 1938




1933 1934 1935 1936 1937 1938


5,147 5,147 5,147 5,147 5,147 5,147 5,147


4,773 4,773 4,773 4,773


7,222 7,870

7,035

7,534 7,)25 6,355 7,324


1,:3) 2,587 1,752 2,251 2,642 1,072 2,040


9,858 14,287 7,488 11,667 15,089 4,232


Average








TABLE 18B.-ToTAL OPERATING COSTS OF PUMPING PLANTS, INCLUDING FIXED CHARGES.


Av.
Plant Year S atic
Lift
Feet

East Pahokee 1933 4.6

Unit No. 1 1934 4.7

1935 4.9

1936 4.2

1937 4.5
1938 2.9

Average 4.4


East Pahokee 1933 4.7

Unit No. 2 1934 4.7

1935 4.4
1936 3.6

1937 4.5
1938 2.3

Average 4.1


Water Area Fixed
Pumped Served [Charges Acre-Feet I Acres Dol~ars 15,607 5,798 7,019 16,588 5,798 7,019 11,210 5,798 7,019 12,627 5,798 7,019 15,556 5,798 7,019 8,414 5,798 7,019 13,334 5,798 7,019


28,609 30,271 21,385 26,071 19,747 18,796 24,146


9,478 9,478 9,478 9,478 9,478 9,478 9,478


9,826 9,826 9,826 9,826 9,826 9,826 9,826


Main- Oils& Costs for Year
tenance Labor Total Per Acre JPerAc.Ft.I PerAc.Ft.
Amount Served I Pumped ILiftedift.


Dotlars


750 750 750 750 750 750 750


1,050 1,050 1,050 1,050 1,050 1,050


1,050


Dollars Dollars I 2,263 10,032 2,554 10,325 1,768 9,537 2,228 9,997 2,389 10,158 1,491 9,260 2,116 9,885


3,459 14,335


3,821 2,482 3,175 2,492 2,088 2,920


14,697 13,358 14,051 13,368 12,964 13,796


Dollars Dollars Dollars
1.73 0.64 0.14

1.78 0.62 0.13

1.64 0.85 0.17

1.72 0.79 0.19

1.75 0.65 0.14

1.60 1.10 0.38

1.70 0.74 0.17













TABLE 18c.-TOTAL OPERATING COSTS OF PUMPING PLANT AT FVEX1LADES EXPERIMENT STATION, INCLUDING FIXED CHARGES.


Av. Water
Plant Year Static Pumnped
Lift
Feet I Acre-Feet Everglades 1933 2.0 1,670

Exp. Station 1934 2.3 1,499

1935 2.3 1,349

1936 2.1 1,822

1937 2.2 1,076

1938 1.7 329

Average 2.1 1,291


Area Fixed Served Charges Acres Dollars

102 818

162 318

162 318

180-ti 318 180-- 318 180-+- 318 171 1 318


Electric Costs for Year
Main- Power
tenance and Total Per Acre PerAc.Ft-.1 PerAc.Ft.
Labor Amount Served Pumped i Liftedlft. Dollars Dollars Dollars Dollars Dollars Dollars

34 860 1,212 7.48 0.73 0.36

:34 855 1,207 7.45 0.81 0.35

24 825 1,177 7.26 0.87 0.38

34 911 1,263 7.02 0.69 0.33

34 698 1,050 5.84 0.98 0.45

34 295 647 3.59 1.97 1.16

34 741 1,093 6.44 0.85 0.40






Florida Agricultural Experiment Station


The fixed charges for the four oil engine plants average approximately two-thirds of the total costs of pumping. The four plants will also average about one gallon of fuel oil per acre-foot pumped. Most of the cultivated land of the northern Everglades is served by pumping units similar to those of the East Pahokee District and it is estimated that the depth pumped will average approximately three feet per year over the area served. Of the four plants considered, probably the costs shown for East Pahokee Unit 1 will more nearly approximate the average costs for the pumped lands. In comparison with the value of crops raised, pumping costs are very low. In addition to the cost of pumping, proper maintenance of ditches and levees would amount to about $2 an acre per year.
The cost tables for the Everglades Station plant show an average annual cost for electric power and labor of $4.33 per acre served and $0.57 per acre-foot pumped. The total costs, including fixed charges, have averaged $6.44 per acre served, $0.85 per acre-foot pumped, and $0.40 per acre-foot lifted one foot. The fixed charges average about one-third the total cost of operation. The rainfall in 1938 was only 41 inches and very little pumping was done. Hence the low costs per acre served and the high costs per acre-foot pumped for that year. Very little pumping of the peat lands is done with electric power.
Rainfall for 1937 was 58.44 inches; depth pumped for drainage was 6.0 feet; and evaporation is estimated at 3.5 feet. Seepage into the pumped area, based on the above data, was approximately 4.6 feet during that year of nearly normal rainfall. This is equivalent to an average inflow of about 500 gallons per minute into the area pumped by the Experiment Station plant. A higher water table without or a lower water table within an area will increase the seepage. A comparison of the amount of pumping with the stages of the Hillsboro Canal clearly shows this effect.
Average annual consumption of electric energy by the Experiment Station plant over the six-year period has been 10,920 kilowatt hours and has cost $666.

EFFICIENCY TESTS ON PUMPING PLANTS
Overall efficiency tests were made at each of the oil engine plants in 1935 and the results are shown in Table 19. The discharge of the pumps was measured with a Pitot tube and the fuel consumed in an hour's time was carefully weighed. The static lifts are the difference in readings of the gages just out-






TABLE 19.-EFFICIENCY TESTS OF Oil, ENGINE PLANTS.


Pel



1/
U


Eam II
I
I
I


Discharge Work
Plant Pump Speed per Static of Pump by
No. Minute Lift per Minute Plant
Revolutions Feet Pounds H. P.

ican Lake
Jnit No. 1 1 276 4.25 227,600 29.3
Jnit No. 1 .2. . 270 4.72 201,300 28.3

Jnit No. 2 . 1 272 3.22 232,100 22.6
Jnit No. 2 .1 269 5.77 182,700 32.0
Unit No. 2 ----- . 2 290 5.95 227,600 41.1
Jnit No. 2 2 275 3.27 234,300 23.2

st Pahokee
Jnit No. 1 1 250 5.80 441,500 77.6
Jnit No. 1 . 1 227 6.15 391,500 72.9
Jnit No. 1 . . 1 202 5.96 301,800 54.6
Unit No. 1 . 1 177 5.96 240,000 43.4
Jnit No. 1 ----. . 2 248 5.14 457,000 71.2


Unit No. 1 ---Unit No. 2 Unit No. 2 Unit No. 2 ---Unit No. 2 --Unit No. 2 .


2

J 1
. 1 S 1 . 1 S 1


U nit N o. 2 . . U nit N o. 2 . . U nit N o. 2 . U nit N o. 2 . U nit N o. 2 -------------------*Value probably too high.


256 256 226 200 176


395,100

483,500 418,200 356,000 279,200 148,600

488,000 480,000 401,100 336,500 263,500


61.8

73.2 62.3 53.3 43.7 23.7


Fuel Oil Energy Overall
Used Output Efficiency
per Hour of Engine of Plant Pounds Brake H.P. Percent


37.4 74.9 31.
34.5 69.0 33.

30.8 61.6 29.
36.4 72.9 35.
46.8 93.6 35.
31.2 62.4 30.


73.7 66.1 54.0 41.4 70.5 57.2

75.5 57.2 46.1 38.6 29.1

71.3 79.0 63.1 47.5 39.2


147.5 132.3 108.0 82.8 141.0 114.5

151.0 114.5 92.2 77.3 58.2

142.6 158.0 126.2 95.0 78.4





Florida Agricultural Experiment Station


side the screens at either end of the plant. The useful work done by the plant, or water horsepower, is, based on the pump discharge and static lift. The energy output of engines is estimated on the basis of 0.50 pounds of fuel oil per brake horsepower. The overall efficiency is the ratio of the water horsepower hours to the indicated horsepower hours or energy used in the engine. The mechanical efficiency or ratio of the brake horsepower to the indicated horsepower is estimated at 80 percent. The term "plant" in Table 19 refers to a complete pump and engine unit. Each plant has two or three such units. It is evident that the East Pahokee plants are much more efficient than the Pelican Lake plants. The East Pahokee pumps are of larger size and probably more recent design. Efficiencies based on fuel consumption and brake horsepower are necessarily only approximate.
In October, 1937, several efficiency tests were made on the Experiment Station pump. The power input was measured by the watt-hour meter and the discharge with a standard weir. The motor is connected to pump with V-belts. The motor efficiency used was 88 percent and the belt efficiency 94 percent. The static lift was measured inside the pump house. The results were as follows:
Pump Static Pump Work Energy Efficiencies
Speed Lift Discharge Done Used Overall Pump
R.P.M. Feet See. Feet H. P. H. P. Percent Percent 574 4.33 17.95 8.82 26.2 34 41
442 3.94 11.72 5.24 15.1 35 42
292 3.46 5.00 1.96 7.9 25 30
The pump used in these efficiency tests was a 24-inch vertical turbine driven by a four-speed Westinghouse induction motor rated 30 horsepower at 1,180 revolutions per minute. A large number of pumps of this type are used in the northern Everglades, but only a few are operated by electric power. This pump was later re-conditioned and the discharge was improved.
Capacity of Pumps.-A 12-year record of rainfall at the Everglades Experiment Station shows the following average periods between rains: Av. Number Av. Period
Size of Rains per Yr. in Months
1.0 inch or more --- -------------------- 17.2 0.7
1.5 inch or m ore --------------- ------------ -- 8.1 1.5
2.0 inch or m ore --------------- ---------------- 4.0 3.0
2.5 inch or more ------ ___ ------------------ 2.3 5.2
3.0 inch or m ore ------- ------------------------ 1.4 8.5
3.5 inch or m ore -_-----_-------------- ------- 1.0 12.0
4.0 inch or more ------------_---------- ------- 0.58 20.6
4.5 inch or more . ----- - ---------- . - 0.33 36.4
5.0 inch or m ore --------------------- -------- - 0.25 48.0






Water Control in the Soils of the Everglades 59

The above figures indicate that excessive rains are not very frequent. The probability of rains of two inches or more is four in a year; of 3.5 inches or more is one in a year; and of 5 inches or more is one in f our years. Many of the heavy rains occur during the three summer months when there is little or no farming. Nearly half of the rains of two inches or over occurred in that period. The damage f rom excessive rains is reduced to a considerable extent by the high absorptive capacity of the peat soils. Under usual conditions an inch of rain will raise the water table about six inches. If the water table were two feet deep, about four inches would be required to saturate the soil. However, as the top soil is changed by cultivation and weathering, the seepage movement is retarded and water will remain on the surface for a considerable period with the ditches at a low stage. Heavy rains sometimes occur when the water table is high and the soil wet from previous small rains. Certainly not more than two inches should be the allowance for the decrease in pump capacity on account of soil absorption. On this basis pumps with a one inch capacity would handle all rains up to three inches and the 12-year record shows only 11 rains of three inches or more outside the summer months. With pumps of 2-inch capacity, rains up to four inches could be cared for in this area, and only six rains of four inches or more have occurred outside the summer. With a 3-inch pump capacity a 5-inch rain could be cared for. The 12-year record shows three rains of five inches or more and one of these fell in the summer period.
The Wood-screw type of pumps used in the larger drainage units have a capacity of approximately one inch in 24 hours. Experience indicates that this rate of discharge is sufficient for sugarcane. During recent years nearly all the pumps installed to serve land used mainly for truck crops have had capacities varying from 1.5 to 3.0 inches. The Experiment Station pump has served from 160 to 180 acres in recent years and the record shows that a 2-inch discharge has been sufficient except in the case of very exceptional rains. For rains exceeding 3.5 inches a greater rate of run-off is usually needed. Only 14 such storms have occurred in the last 15 years and five of these have been in the three summer months. Pumps serving truck lands should have a capacity of two to three inches. The proper depth of run-off will depend on the value of crops raised and also on the area drained. A run-off of more than three inches probably could not be justified on economic grounds. Private pumping





Florida Agricultural Experiment Station


units within a large drainage system are of value in controlling the water table on individual farms, but the run-off provided by such units should not greatly exceed that of the main system.

FARM DITCHES
District laterals are usually spaced a half mile apart along section and half section lines. Farm ditches are spaced from 1,320 to 660 feet apart, the closer spacing being generally used for truck crops. The depth of run-off which these ditches will carry should be equal to that provided by the pumps. The ditch banks should have a 12 to 1 side slope. As the land is practically flat, a three-inch fall per mile is commonly used in calculating ditch sizes.
The maintenance of ditches is an important problem. Water plants such as hyacinths or moss commonly cover or fill the channe's and Para grass grows readily on the banks. Such growth greatly reduces the capacity of a ditch. In addition to these, a soft soupy sludge collects in the bottoms. These growths and deposits should be removed at regular intervals. The ditch banks should be sodded to prevent the growth of weeds and Para grass. The sludge in the bottoms of ditches can best be removed with a pump type of ditch cleaner.

MOLE DRAINAGE
Subdrainage and subirrigation is accomplished by means of moles.' These are formed by drawing a 6-inch, bullet-nosed cylinder through the soil between farm ditches. The depth is commonly 30 inches and the spacing from 12 to 15 feet. The resulting hole is about 4 / inches in diameter.
Cleaner mole holes result if the moling is done when the water table is below the mole depth. Spring is the best time to do this work, f or it then requires less pumping to hold a deep water table.
If the mole work is well done, the lines will probably give satisfactory sub-drainage for a period of from five to eight years. At the end of the effective period the field can readily be re-moled. The cost of such work is about 50 cents per acre.
Following a heavy rain the water table in a moled field will drop more rapidly than in a similar field not moled. Some obser7Allison, R. V. Movement of underground waters. Florida Agr. Exp. Sta. Ann. Rpt. 1928: 117R-118R.































Fig. 10-Mole entering soil at side of ditch. Note vertical cut in bank from mole to surface of the soil where the blade that precedes the mole has entered.

vations at the Everglades Station indicate that after a rain has saturated the soil the water table in a moled field will drop a foot in about one third the time required for a field without moles.
In a pumped area subject to pressure, due to higher water outFig. 11.-Mo'ing machine in operation. The mole (as shown in Fig. 10) is being drawn through the soil at the bottom of a heavy blade carried at the end of the eye-beam and directly beneath the man on the machine at the right.





0%.






Florida Agricultural Experiment Station


side the dikes, the water table in the fields will usually stand substantially higher than that in the ditches. In such cases the mole drains will tend to level out the water table and reduce this difference.
As far as possible it is best to install the mole lines before digging the farm ditches, for in this case the moles will have outlets in ditches at either end, whereas if the work is done later each line will have a dead end. Also the depth should not be less than 30 inches, for experience has shown that shallower lines may be closed up by the weight of farm machines.

WATER TABLE STUDIES
THE WELL LINES
In the spring of 1932 a number of well lines were established to record the rise and fall of the ground water elevations in certain areas near Lake Okeechobee. For several years prior to 1932 the Everglades Station made weekly readings along several lines on the station property. Two of these lines extended in a southwesterly direction from the Hillsboro Canal and across several farm ditches located 240 feet apart.
The data indicated that with a high level in the Hillsboro Canal the seepage gradient diminished rapidly with distance from the canal. On irrigation tests the data also showed that the plot water tables were substantially below the high level in the ditches. Line "G," mentioned in this report, was one of these old lines and the subsequent data were consistent with the earlier measurements. A third line extended from the Hillsboro Canal across virgin land owned by the Experiment Station. This line was relocated in 1932 and designated as Line "A" and readings were continued for several years.
The location of the lines as established in 1932 are shown on Figure 1. A chart for each line shows the fluctuations of the water table in a typical well over a period of several years. The rainfall, lake or canal levels and other data affecting the ground water levels are also shown. A profile for each of the lines shows typical ground water curves, the depth of peat, and the distance between wells. Charts and profiles have been prepared for 12 lines designated as A, B, C, D, E, G, M, 0, Q-R, S, T, and U. A map showing ties to section corners and a short discussion of the water table variations has been prepared for each of the lines.






Water Control in the Soils of the Everglades


In this report, data f or only a few of the more important lines are presented. Charts and profiles for the remaining lines may be secured from the Soil Conservation Service, Washington, D. C.
Well Line D.-Line D (Fig. 1) begins at the old levee on the south side of Lake Okechobee and extends south across the east portion of Sections 5 and 8; Township 44, Range 36, to the Florida East Coast Railroad. The location is about a quarter mile west of the east line of these sections, and is in the South Shore Drainage District. A road ditch along the north side of Section 8 provided some drainage for the land. The drainage


Fig. 12.-Hydrographs of Wells 8 and 27, Line D, and Lake Okeechobee; rainfall near Line D.










JANUARY FEBRUARY MARCH '935


APRIL MAY _ JUNE _j A RY FEBRUARY MARC A MAY JUNE -j


Fig. 13.-Hydrographs of Wells 8 and 27, Line D, and Lake Okeechobee; rainfall near Line D.






Water Control in the Soils of the Everglades


district had no permanent pump installations until the spring of 1938, when a 35,000-gallon pump was installed. Land south of the railroad line is in the South Florida Conservancy District, which is drained by pumps. The water table along Line D is probably lowered somewhat by seepage into this pumped land during the summer and fall months.
The soil is Okeechobee (custard apple) muck underlaid with limestone at an average depth of 7.5 feet. During the period of the record the land was used for truck crops. The drainage was not very good until pumps were installed in 1938.
Well records on this line began in May, 1932, and readings were made about once a week until July, 1934, when automatic gages were installed at Wells 8 and 27. Figures 12 and 13 show the variations in water tables at these wells and also the stages of Lake Okeechobee. The rainfall shown is the average of that at South Bay and Lake Harbor. Figure 15 shows a profile along line D and the depth of soil.
The lowest stages in both wel's occurred in May, 1932, when the lake was at a record low stage. The low stages were preceded by nearly a year of very low lake levels and by more than a year of subnormal rainfall.
Well 8 is located 1,000 feet south of the old Everglades District levee and 1,700 feet south of the new Government levee. The stages in this we'l are strongly affected by the lake level. Near the end of the dry season in the latter part of May or early June the well water has averaged about 0.7 feet below the lake and the extreme differences have ranged from 0.5 to 1.5 feet. The corresponding lake elevations have varied from 12.5 to 15.8 feet. The extreme differences between lake and well stages in January averaged 0.6 feet and ranged from 0.4 to 1.0 feet. The low lake stage for January, 1933, was 14.5 and for January of the years 1934 to 1938 was approximately 16 feet.
Well 27 is located 5,000 feet south of Well 8 and 6,700 feet from the new levee. The extreme low stages in the latter part of May or early June averaged 2.3 feet below the lake and varied from 1.0 to 3.2 feet below. The extreme low stages for January averaged 2.2 feet below the lake and varied from 1.6 to 2.6 feet below.
Wells 8 and 27 are almost one mile apart. The extreme low stages in January for the years 1933 to 1938 show an average difference of 1.5 feet and those for May or June a difference of 1.8 feet. This greater slope at the end of the dry season is






Florida Agricultural Experiment Station


doubtless due to the fact that evaporation and seepage have lowered the water table in land south of the cultivated area.
On account of variation in rainfall and other conditions, it is difficult to determine the effect of changes in lake stage on the water table in the outer lands. Although a comparison of lake stages with the stages in Well 27 do not show a consistent diff erence, it is evident that a substantial change in lake elevation has some effect on this well. However, the effect appears to be small and it seems probable that an increase of two to three feet in the normal lake height would cause no substantial increase on the water table several miles out.
The new levee was completed across the end of Line D in the summer of 1935. Beneath the levee are two trenches which were excavated to rock and then refilled with marl and shell. The purpose of the one near the inner toe is to prevent fires from reaching the organic materials beneath the fill and that of the other is to decrease seepage. A comparison of the stages in Well 8, before and after the levee was completed, indicate that the construction of the levee has had little effect on the water table near this well.
Well Line E-Line E begins at the edge of Lake Okeechobee, about 11/4 miles northeast of Pahokee, in Section 8, Township 42, Range 37, and extends in a southeasterly direction through the Boe farm to the Florida East Coast Railroad. The line crosses a sand ridge at a point 610 feet from the levee. Well 6, at the east toe of the ridge, is 710 feet from the levee and Well 10 is 1,440 feet from the levee. East of the railroad is a low area once covered by Pelican Lake. This is now drained by pumps and as a result the water table along this line is lowered by seepage into this low area. The soil east of the sandy ridge is deep Okeechobee "custard apple" muck and is used for truck crops.
Readings along this line began in - May, 1932. In July, 1934, an automatic water level recorder was installed at Well 10. The principal purpose of the line was to show the effect of lake stages on the water table in the adjacent land. Figure 14 shows the water levels in Wells 6 and 10, lake stages, and rainfall for the first half of the years 1935 to 1938. This period is used because it includes the dry part of the year when the rainfall and water tables are at minimum and the effect of lake stakes are most apparent. Figure 15 shows a profile along this line.
In January, with a normal lake elevation of about 16 feet, the







JANUARY I FEBRUARY MARCH I APRIL MAY JUNE JANUARY I FEBRUARY I MARCH I APRIL MAY JUNE

1935 1936
r-M, Approx vote ground sufac ~ well eIno 10


5 ,W e ll 6
4 I ,f-WeIJ ;0

3 ---l-4 33 54 12,47
00 00 030 _779 6 763 256 46031_L 4
1937 1938

.Aoeroge ground su, ece neor well .O10
, "" " " .- LokeOeeoee04

--- - --------- -







3860
3 343[


Fig. 14.-Hydrographs of Wells 6 and 10, Line E, and Lake Okeechobee; rainfall at Azucar.






































Fig. 15.-Profiles of Lines D and E.





Water Control in the Soils of the Everglades


lowest readings at Well 6 have averaged 1.6 feet below the lake and those at Well 10 have averaged 2.6 feet below lake level. The difference of one foot between these wells is equivalent to a slope of 7.2 feet per mile in the seepage gradient. The extreme low readings in these wells occur near the end of the dry season in May or early June. With a lake elevation of about 15, the low readings in this period have averaged 2.4 feet below the lake at Well 6 and 3.7 feet at Well 10. The difference of 1.3 feet between these wells is equivalent to a slope of 9.4 feet per mile in the seepage gradient. This increase of slope between January and May or June is due to a lowering of the water table in the adjacent lands by seepage and evaporation.
The new levee across the head of Line E was closed in October, 1935. Beneath the fill are two trenches which were dug to rock and refilled with marl and shell. It is probable that very little seepage can penetrate these fills. A study of the well readings along Line E indicates that the new levee has had no substantial effect on the water table in adjacent lands. This and other observations appear to show that the seepage movement between the lake and adjacent lands takes place through the porous limestone and sand beneath the peat rather than directly through the peat deposit.
On account of the variation in rainfall and amount of pumping, it is difficult to determine the effect of changes in lake stage on the water table in this area. A substantial change in lake stage will raise the water table at Well 6, but the raise is considerably less at Well 10. The effect certainly decreases with distance from the lake. A change of several feet from normal lake level would probably have no substantial effect on the water table a few miles from the levee. As previously noted, the water table at Line E is affected by the low land in the old Pelican Lake area. The water table along Line D is the more typical of the general condition around the lake. The lake level is regulated as nearly as possible between 14 and 17 feet. The average stage of 16 feet is probably the most favorable height for present agricultural conditions. However, as the farm lands continue to subside a lower level may become desirable.
As the water table in the peat land near Lake Okeechobee is affected by rainfall, pumping, lake and canal stages, it is difficult to draw general conclusions from a study of fluctuations along well lines. The study, however, shows that the water table in a field is usually not the same as that in the ditches. Follow-





Florida Agricultural Experiment Station


ing a rain the profile of the water table between ditches shows a very flat curve with a rather sharp drop to ditch levels near the ends. This curve will slowly flatten as pumping continues and during dry spells with no pumping may reach a point about one-half foot below ditch levels. Fields adjacent to a levee with high water stage outside may have a water table close to the surface when the interior drainage ditches are at a low level. This pressure causes a seepage flow through the porous rock or sand and thence upward into the fields. If the water table outside a dike were held a foot above the land within it is probable that a strip about 100 yards wide would be too wet for satisfactory farming even though the ditches were held at a low level by pumping. A small ditch along the toe of a dike will substantially depress the seepage gradient.

WATER TABLE PLOTS
To determine the effect of water table depth on crop yields eight water table plots were established at the Everglades Station. The plots are approximately 100 by 240 feet in gross size, and are surrounded by ditches on three sides. Mole drains 15 feet apart extend across each plot and connect the side ditches. Two 1,000-gallon pumps with electric motors maintain the desired water tables at near-constant levels. Two of the plots are equipped with overhead spray lines.
One-third of each plot has been planted to sugarcane, one-third is used f or truck crops, and the other third is used for grass or forage crops. The water tables in the several plots varied from approximately one to three feet. During the years 1937 and 1938 water table depths of 1.0, 1.5, 2.0, 2.5, and 3.0 f eet were held as nearly as possible in the particular plots.
For about 18 months before operation the water table was approximately the same in the whole area and during this period corn was grown on all plots to determine their relative productivity under conditions of equal water tables. The maintenance of definite water tables at different levels was begun in November, 1935.
After a few more crop years a complete report will be prepared covering the crops as well as the soil conservation phases of these water table experiments. The results so far obtained indicate that a 1.5 to, 2.0-foot water table is best for truck crops; that grasses do well on a table held at from 1.0 to 2.0 feet; that some






Water Control in the Soils of the Everglades


varieties of sugarcane produce good yields on a 1.0 to 1.5-foot table while other varieties do better on a deeper table.
The canes producing best on a high water table are of particular value from a soil conservation standpoint, for the higher the water table the less is the surface subsidence of the land.

SUMMARY
An outstanding need of the Everglades is a comprehensive plan of water conservation whereby the water now wasted could be used to maintain a higher water table in the idle lands and thus decrease the losses from subsidence and fires. This should also provide for a definite system of outlet canals for all land of agricultural value so that an orderly development could be achieved. Under present conditions expansion is taking place without such a plan, thus complicating the problem of providing a consistent scheme for the whole area.

SOILS
The major portion of the peat lands of the Everglades consists of the partially decayed residue of sawgrass deposited over a period of thousands of years. A field sample of this soil when oven-dried loses about three-fourths of its weight. The ash or mineral content is about 10 percent of the dry weight. After drainage and cultivation for a period of 10 to 15 years the dry weight of the top 18 inches of soil about doubles. The Okeechobee (custard apple) or plastic muck on the east and south sides of Lake Okeechobee has a mineral content of 35 to 70 percent of the dry weight. Between the "Everglades" peat and the plastic muck is an area of Okeelanta peaty muck (willow and elder) land with a mineral content intermediate between the peat and the muck.
SUBSIDENCE
Subsidence of peat soils is due to natural oxidation, fires, shrinkage and compaction caused by lowering the water table and cultivation. The loss in elevation of the drained deep peat lands in the northern Everglades has been approximately five feet since drainage. About 1112 feet of this loss is accounted for by the increase of dry weight in the upper portion of the soil. The present rate of loss is approximately one inch per year. The loss is about proportional to the average depth of






Florida Agricultural Experivient Stotimi


water table. Okeechobee (custard apple) muck subsides somewhat slower than sawgrass land.

SEEPAGE
The rate of seepage through virgin sawgrass peat soil is very slow in a horizontal direction. However, after cultivation and weathering, the vertical movement through the top portion of the soil also becomes very slow due to changes in the soil structure. There appears to be a considerable movement of the seepage water through the porous rock and sand beneath the peat. Pumping records show that a large part of the water pumped enters the drained area through seepage.

RAINFALL, EVAPORATION AND TEMPERATURE
In the northern Everglades the average rainfall for the fourmonth period from June to September is approximately 60 percent of the mean annual amount. A 141/2-year record at the Everglades Experiment Station shows an average annual rainfall of 57.3 inches. The greatest intensity for a one-hour period was 3.25 inches.
Estimates based on tank experiments with sugarcane indicate an annual evaporation and transpiration from cane fields of 42 to 45 inches per year. Similar experiments with sawgrass showed an annual loss of 84 inches from a dense stand of grass and 68 inches after the stand had deteriorated to some extent. As the average stand over the sawgrass areas of the Everglades is less dense than that in the experimental tanks, it is estimated that the loss from such areas would approximate 60 inches per year.
The lowest temperature recorded in the Everglades was 9,-'F. at Shawano on virgin sawgrass land. A comparison of low temperature records indicates that minimum readings will be about 4 degrees higher on cultivated land than on nearby virgin land at temperatures below 380 F.

WATER CONTROL BY PUMPING
Pumps are essential for the proper control of water in the northern Everglades. The sub-drainage districts of this area have a total rated pumping capacity of 4,200 second-feet. In addition to these sub-district pumps there are a large number of small pumps serving private farms. The area served by






Water Control hi the Soils of the Everglades


pumps in the northern Everglades is approximately 100,000 acres.
Most of the sub-districts are served by large pumps of the Wood-screw type with a capacity of approximately one inch over theareaserved. Records have been kept for four pumping plants of this type over a period of six years. The average static lifts of these plants varied from 3.5 feet to 4.4 feet. The fuel oil consumption was approximately one gallon per acre-foot of water pumped. The mean annual depth pumped over the six-year period varied from 2.3 feet for one of the larger units to 4.4 feet for one of the smaller units and the total cost of pumping, including fixed charges, varied from S1.45 to S2.57 per acre served. The fixed charges amounted to about t,,vo-thirds of the total cost of pumping.
The annual cost of elecfi ic power at the Everglades Experiment Station plant, over a period of six years, averaged 83.90 per acre served and 6.1 cents per k.w.h. used, and the average period of plant operation was 49 days per year. The amount of pumping depends very much on the stage of the Hillsboro Canal, as this affects the rate of seepage into the pumped area.
A pumping capacity of two to three inches is recommended for areas of moderate size used to grow truck crops. The proper depth will depend on the kind and value of crops grown and also on the size of area drained.

DITCHES AND SUB-DRAINAGE
Collection ditches should have a total capacity equal to that of the pumping plant, and should be kept clean of hyacinths, moss and grasses, which greatly reduce the channel capacity.
Mole lines, usually spaced 12 to 15 feet apart and 30 inches deep, provide an inexpensive sub-drainage system and increase the rate of drop of the water table after heavy rains.

WATER TABLE STUDIES
Records from well lines near Lake Okeechobee indicate that the new lake levee has had little or no effect on the seepage gradient from the lake to adjacent lands. A continuous water table record has been kept at a well 6,700 feet south of the new levee near Bean City. During the dry periods from January to June with the lake at a 15 to 16-f oot stage the water table at this well was approximately 2.3 feet below the lake. A substantial change in lake level appeared to have a small effect at






74 Florida AgricuItural Experiment Station

this point, but at a distance of several miles from the lake it is believed the lake effect would be negligible.
Water table studies at the Everglades Experiment Station indicate that truck crops give best results when the depth to water is 1.5 to 2.0 feet, while grasses and some varieties of sugarcane do well when the water in the soil is maintained at an appreciably higher level. Such considerations, under practical conditions in the field, shall have to take into account such features as transportation in the field, plant anchorage in relation to wind damage, and many others.




Full Text

PAGE 1

Bulletin 378 November, 1942 UNIVERSITY OF ;r/'LORIDA AGRICULTURAL EXPERIMENT STATION WILMON NEWELL, Director GAINESVILLE , FLORIDA Cooperating with UNITED STATES DEPARTMENT OF AGRICULTURE SOIL CONSERVATION SERVICE H . H . BENNETT, Chief WATER CONTROL IN THE PEAT Ar~D MUCI( SOILS OF THE FLORIDA EVERGLADES By B. s. CLAYTON, J. R. NELLER and R. v. ALLISON Single copie s free to Florida residents upon request to AGRICULTURAL EXPERIMENT STATION GAINESVILLE. FLORIDA

PAGE 2

EXECUTIVE STAFF John J. Ti g ert, M.A., LL.D., Pr esid ent of the Univc rsit y 3 Wilmon Newell. D .Sc. , Director 3 Harold Mowry, M.S.A., Asso. Director L. 0. Gtatz, Ph.D . , A ss t. Dir., Research W. M. Fifield , M.S., Asst. Dir. , Admin. 4 J. Francis Cooper , M.S.A., Editor" Clytle B ea le, A.B.J ., Assistant Etlitor' Jefferson Thomas, A ss istant Editor 3 Ida Keeling Cresap, Librarian Ruby N ew hall, Administrative Manager 3 K. H. Graham, Bu s ine ss Manager 3 Cfal' ane ll e Alderm a n, Accountant 3 MAIN STATION, GAINESVILLE AGRONOMY W. E. Stokes. M.S .• Agronomistl W. A. Leukel, Ph.D., Agronomist " Fr, , ! H. Hull, Ph.D., Agronomi s t G. E. Ritchey, M.S. , A s sociate' W. A. Carver, Ph . D., Associate Roy E. B laser, M.S., Associate G. B. Killinger, Ph.D., Associat e Fred A. Clark, B.S . A . , Assistant ANIMAL INDUSTRY A. L. Shealy, D.V.M., An. Industrialist' R. B. Becker, Ph.D., Dairy Husbandman• E. L. Fouts, Ph.D., Dairy Technologist 3 D. A. Sanders. D.V.M., Veterinarian M. W. Emmel , D.V.M . , Veterinarian 3 L. E. Swanson, D.V.M., Para s itologist• N. R. Mehrhof, M.A g r., Poultry Hush. 3 T. R. Freeman, Pl':.D., Asso. in Dairy Mfg. R. S. Glasscock, Ph.D., Asso. An. Hush. D. J. Smith, B.S.A., Asst. An . Hush." P. T. Dix Arnold, J\I.S.A., As s t. Dairy Hush.' G . K. Davis , Ph . D ., Tech. in An. Nutrition L. E . Mull, M.S., Asst. in Dairy Tech.' 0. K. Moore, M.S. , As s t. Poultry Husb. C. B. Reeves, B.S., Asst. Dairy Tech. J. E. Pace, B.S., A ss t . An. Hush. ECONOMICS, AGRICULTURAL C. V. NobJe, Ph . D ., Agr. Econom is t 1 :i Zach Sa vage , M.S.A., Associate A. H. Spurlock, M.S.A., Associate Max E . Brunk, M.S . , Assistant ECONOMICS, HOME Ouida D . Abbott, Ph.D., Home Econ. ' Ruth 0. Townsend, R . N .. Assi s tant R. B. French, Ph.D., Asso. Ch e mist ENTOMOLOGY J. R. Watson, A.M .• Entomo1o gh;t 1 A. N. Tissot, Ph.D., Associate H. E. Bratley, M.S . A., Assistant HORTICULTURE G. H. Blackmon, M.S.A., Horticulturist' A. L. Stahl, Ph.D., Associate F. S. Jamison, Ph.D . , Truck Hort. R. J . Wilmot, M.S.A., Asst. Hort. R. D. Dickey, M.S.A., Asst. Hort. J. Carlton Cain, B.S.A., Asst. Hort.' Victor F. Nettles, M.S.A., Asst. Hort.• Byron E. Janes, Ph.D., Asst. Hort. F'. S. La g assee, Ph.D., Asso. Hort . 2 H. M. Sell, Ph.D., Asso. Hort." PLANT PATHOLOGY W. B. Tisdale, Ph . D ., Plant Pathologist' George F. Weber, Ph.D., Plant Path. 3 Phares Decker, Ph.D., Asso. Plant Pathologist Erdman West, M.S., Mycologist Lillian E. Arnold, M.S., Asst. Botanist SOILS R. V. Allison, Ph.D., Chemist> Gaylord M. Volk, M.S .. Chemist F. B. Smith, Ph.D., Microhiologist 3 C. E. Bell, Ph.D., Associate Chemist J. Russell Henderson, M.S.A., Associate• L. H. Rogers, Ph.D., Asso . Biochemist' Richard A . Carrigan, B.S., Asso. Chemist' L. E. Ensminger, Ph . D., Asso. Soils Chem. H. W. Winsor, B.S.A., Assistant Chemist Geo. D. Thornton, M.S., Asst. Chemist R. E. Caldwell, M.S.A., Soil Surveyor Olaf C. Olson, B.S .. Soil Surveyor BOARD OF CONTROL H. P. Adair, Chairman. Jacksonville R. H. Gore, Fort Lauderdale N. B. Jonlan, Quin cy T. T. Scott, Live Oak Tl:os . W . Bryant, Lakeland J. T. Di a mond Secretary, Tallaha sse e BRANCH STATIONS NORTH FLORIDA STATION, QUINCY J. D. Warner, M.S., A~ronomist in Charge R. R. Kincaid, Ph . D . , Asso. Plant Patholo g ist R. W. Wallace, D.S. , As so, Agronomist J. H. Wallance, M.A . , Asso. A gro nomist Elliott Whi(ehurst, B.S.A., Asst. An. Hush.' W. C. McCormick, B.S.A., Asst. An. Hush. Jesse R ee ves, Asst. Agron., Tobacco W. H. Chapman, M.S., Asst. Agron.• CITRUS STATION , LAKE ALFRED A. !". Camp, Ph.D., Horticulturist in Charge V. C. Jamison, Ph.D . , Soils Chemist B. R. Fudge, Ph.D., Associate Chemist W. L. Thompson, B.S., Associate Ento. F. F. Cc,wart, Ph.D., Asso. Horticulturist W. W. Lawless, B.S., Asst. Horticulturist' R. K. Voor.hees, Ph.D., Asso. Plant Path. H. 0. Sterling, n.s .. Asst. HoTt. T. W. Young, Ph.D., Asso. Hort., Coastal C. R. Stearns, Jr., B . S.A., Chemist EVERGLADES STA .. BELLE GLADE J . R. N e ll er, Ph . D ., Biochemist in Charge J. W. Wil so n, Sc.D., Entomolo g ist F'. D. St eve ns, B.S .• Sugarcane Agron. Thoma s B1egger, Ph.D., Sugarcane Physiologist G. R. Townsend, Ph.D., Plant Pathologist R. W. Kidder, M.S . , Asst. An. Hu s h. W . T. Forsee, Ph.D . , Asso. Chemist B. S. Clay t on, B.S.C.E., Drainage Eng. 2 F. S. Andrews, Ph.D., Asso. Truck Hort.' Roy A. Bair, Ph.D., Asst. Aocron. E. C. Minnum, M.S., Asst. Truck Hort. SUB-TROPICAL STA., HOMESTEAD Geo. D. Ruehle, Ph.D . , Plant Path . in Charl!e S. J. Lynch, B.S.A., Asst. Horticulturist E. M. Andersen, Ph.D., Asst. Hort. W. CENT. FLA. STA,, BROOKSVILLE W. F. Ward, M.S., Asst. An. Husb. in Chan re ' RANGE CATTLE STA .. ONA W. G. Kirk, Ph.D., An. Hush. in Charge E. M. Hodges, Ph.D., As so . Agron., Wauchula Gilbert A. Tucker, B . S.A., Asst. An. Hush.' Floyd Eubanks, B.S.A., Asst. An. Husb. FIELD STATIONS Leesburg M. N. W a lker, Ph.D ., Plant Path . in Charge' K. W. Loucks, M.S. , Asst. Plant Path. E. E. Hartwig Ph.D., Asst. Agron. & Path. Plant City A. N. Brooks, Ph.D., Plant Pathologist Hastings A. H. Eddins, Ph.D., Plant P a thologist E. N. McCubbin, Ph . D., Asso. Truck Hort. Monticello S. O. Hill, B.S., Entomologist 2 A. M. Phillips, B.S., Asst. Entomologist' Bradenton Jos. R. Beckenbach . Ph.D., Truck Hort. in Charge E. G. Kelsheimer, Ph.D., Entomologist F. T. McLean, Ph.D ., Horticulturist A. L. Harrison, Ph.D., Asso. Plant Path. David G . Kelhert, Asst. Plant Pathologist Sanford R. W. Ruprecht, Ph.D . , Chemist in Charge, Celery Investigations Jack Ru sse ll, M.S., Asst. Entomoloocist Lakeland E. S. Elli son , Meteor o logist" ' Harry Armstrong, Asso. Met e orolog:ist 2 1 Head of Department. 2 In cooperation with U. S. 3 Cooperative, other divisions. U. of F. 'On leave.

PAGE 3

CONTENTS THE EVERGLADES PROBLEM ..... ........ .. . DESCRIPTION OF THE EVERGLADES AREA . SOILS OF THE EVERGLADES . . ... ... . . SUBSIDENCE OF PEAT SOILS .. . SEEPAGE THROUGH PEAT SOILS . .. .... . CLJMATOLOGICAL DATA .. .. Rainfall ..... . Evaporation and Transpiration Temperature .. . .................. . .. .. . . . . WATER CONTROL BY PUMPING . .... . . Description of Pumping Plants ... . . . . Fixed and Operating Costs of Pum ping Efficiency Tests on Pumping Plants .. . . . Farm Ditches .. . . . . Mole Drainage .. .. . WATER TABLE STUDIES .. The Well Lines ..... Water Table Plots SUMMARY ...... . . Soils . .... . . . Subsidence Seepage ......... . .. ...... . Rainfall , Evaporation and Temperature Water Control by Pumping . Ditches and Sub-Drainage Water Table Studies . . .. ..... . . PAGE 5 8 10 15 17 20 . . ......... .. .. 20 27 35 38 39 . .... . . . .. 47 .... 56 60 60 62 62 70 71 71 71 72 72 72 73 73

PAGE 4

FOREWORD The reclamation and agricultural utilization of the organi c soils of the Everglade s has created a problem of s oil conservation that is vital to the future of this ar ea . The conservation of organic soils under cultivation is no less difficult than it is important. Neith er is it unique to the soil s of the Everglades , s ince the re c ord of reclamation activities on soil s of thi s type in other s tat e s and in oth e r countrie s of the world shows a practically complete disintegration and destruc tion of the s oil body, almost without exception, under conditions of continued use-and abuse. Everglad es soi 1 s require protection a gain s t natural oxidatio~ as well as actual burning, and the con s equent s urface subsidence which occurs under almost any condition of reclamation. We must try to le a rn all th e r e is to b e known about the hand ling of the natural waters of this tremendou s flatland area that we may us e them in such a way as to protect and conserve th e soils under r e claimed as well as unreclaimed conditions, just a s fully as possible . Such an objective i s neither drainage nor ir rigation, but WATER CONTROL in the fullest s ense of the word. The program tow a rds which such an ideal approach points must be broad enough to include the hydrology of the entir e Everglades sy s tem, that is, the Kis s immee watershed and r e lated water s heds, Lake Okeechobe e , and the original overflow area which is the Everglade s itself. Such a plan also must take cognizance of the eccentriciti e s of the climate from year to year. Also it mu s t give most careful c onsideration to the development of adequate water reserves to meet not only ever-increasing de mands for domestic water supplies, municipal and other, and the growing requirements of agriculture as the reclaimed area steadily expands, but also the equally specific needs for soil con servation under unre c laimed condition s . Fortunately the several requirements of the plan do not conflict but can be d e v e loped in full harmnoy with e ach oth e r , provided the question of wat e r supply is h e ld paramount and there i s no s erious shortage at any time. In attacking a problem of this breadth we are, of course, ex ceedingly grateful for the interest and support of such an or ganization as the Soil Conservation Service of the U. S. Depart ment of Agriculture. The Chi e f of this Service, Dr. H. H. Ben nett, has had a deep technical interest in the problems of the Everglades for a great many years, a s has also Mr. L. A. Jones , Chief of the Drainag e Division in the Research Branch of the Service with whose office the cooperation in this phase of the work has been maint a ined. The result s reported in this bulletin relate very closely, of course, to the operation and demonstration project initiated by the Service in 1939 with headquarters in Ft. Lauderdale. This part of the Service's program in the Ever glades is under the management of Mr. C. Kay Davis, to whom we are also very much indebted for the steady interest and co op e ration of his whole staff during the past three years. HAROLD MOWRY

PAGE 5

WATER CONTROL IN THE PEAT AND MUCK SOILS OF THE FLORIDA EVERGLADES By B. s. CLAYTON,1 J. R. NELLER and R. V. ALLISON In the spring of 1932 a cooperative agreement was entered into by the Agricultural Experiment Station of the University of Florida and the Bureau of Agricultural Engineering of the United States Departm ent of Agriculture for the purpos e of investigating problems r ela ting to water control in Florida 2 peat so ils. Headquarters for the work was e st ablished at the Ever glades Experiment Station n ea r Belle Glade. The work has c ontinued s inc e that tim e . Early eff ort s at water control were co nfined to a system of gravity ditche s . Due to so il subsidence and the flat topography of the land thi s m et hod proved inadequate and pumps, installed later, now serve nearly all th e cultivated land. All elevations used in this report are based on the old Punta Rassa datum which has been generally used by drainage dis tr ict s in the n ort he rn Everglades. This datum is approximately 1.4 fee t below the mean se a level datum of the United States Coast and Geodetic Survey. Hence to r ed uce the elevations used to m ea n sea level 1. 4 feet should be subtracted from the figures given. Figure 1 is a map of the northern Ev e rglades showing some of the lar ger drainage ca nal s and pumping plants. THE EVERGLADES PROBLEM The outstanding problem of the Florida Everglade s is con cerned with prolonging the u se ful life of the cultivated land and c ons erv in g th e virgin land s from the destructive e ffect s of sub si dence and fir es . A su cce ssful solution of this problem would benefit the cities of the low er Ea st Coast, si nc e these depend larg e ly on shallow wells for their water supply. Insofar as a higher water table can b e maintain ed in the Glades a larger yield of salt-free water can b e obtained from the se wells. It is also believed that a higher water table would reduce the frost hazards in the cultivated lands. 1 Assoc iate drainag e e ngineer, Soil Conservation Service, U. S. Depart ment of Agriculture, and drainage engineer, Ev erg lad e s Ex per iment Station. "Following a reorganization of the Department, effective July 1, 1939 , the cooperatio n ha s been continued betwe e n the S oi l Cons e rvation Service a nd the Experiment Station.

PAGE 6

6 Florida Agricultural Experiment Station LAKE OKEECHOBEE R. 33E R. 3 4 E. R. 35 E.. R.37 E Fig. 1.-Location of pumping plants, drainage district boundaries, and well lines in the Okeechobee area. R.3 8 E A complete solution of this problem would require a return of the Everglades to their original condition, which is now im practicable. However, if the available water is so distributed that a higher water table is maintained the losses from subsi dence and fires can be much reduced. The useful life of the cultivated lands can be increased by maintaining the highest water table compatible with good crop yields. A water table depth of 1.5 to 2.0 feet produces the best yield for most crops now grown in the Everglades. The water table in the virgin lands can be held somewhat higher by retarding the rate of run-off. The large diagonal canals have increased this rate of run-off and their continuous flow bleeds the Glades of much seepage water which if retained would result in a higher water table. The land on either side of the North New River Canal is about two feet lower than that several miles back, also the water table, during dry weather, is much lower near the canal than several miles out. As far as possible the free flow of these canals should be restricted by

PAGE 7

Water Control in the Soils of the Everglades 7 dams which should remain closed at all times except during extreme high water. If these canals were held at near bank full stage the total amount of pumping would be increased due to seepage into the diked areas, but as pumping costs are low this increase would not greatly change the cost of operation of pumping districts. A system of dikes has been proposed as a means of holding rainfall on the idle lands. There is some doubt as to whether the increased height of the water table during the spring months would be sufficient to justify the costs. Also, it would be diffi cult to protect these dikes from fires. However, the possibility of retaining water by dikes should be examined. Several typi cal areas should be completely enclosed and the results observed before expanding the system. The discharge from Lake Okeechobee through its two outlets averages about 11/4 million acre-feet per year, but due to the elevation of the land outside the levee it would be very difficult to spread this water over the virgin lands. However, some of this water could be used to maintain a high level in the large canals during the dry season, and thus decrease the subsidence losses. Under present conditions the cultivated acreage in the Glades is being expanded without any general plan. This is leading to a condition where much of the land back from the existing roads will have no outlet. Under this condition it is impossible to design outlet canals with any certainty as to the drainage areas which they should serve. This unfortunate situation will be come worse unless some general plan of development is adopted. After a field survey is completed of the agricultural land a map should be prepared and a system of levees and canals pro jected which would provide outlets for all agricultural land. These levees and canals could be constructed as need arises for new land, but would conform with the general plan adopted. All new land should then come in as sub-districts with pumps placed so as to discharge at points provided in the general plan. It might prove feasible to provide north and south outlet ditches along range lines and require sub-districts to extend back three miles. Those interested in forming a new sub-district should first prepare a plan and submit this to some designated authority for approval before work is begun. Only in this manner can a consistent plan of development be achieved. A study of the field data might show that these outlet canals

PAGE 8

8 Florida Agricultural Experiment Station along the range lines could discharge directly into the open Glades without an excessive increase in the lift of the sub-district pumps. If such a plan proved feasible the pumped water would move very s'.owly over the virgin lands and increase the height of water table in these areas. Also it would not be necessary to construct drainage works much in advance of development. Some plan of development is urgently needed and when the survey is completed a study should be made with this end in view. DESCRIPTION OF THE EVERGLADES AREA The Everglades area includes Lake Okeechobee with its tribu tary drainage area; the peat lands known as the Everglades, and the sand ridges on either side. Lake Okeechobee covers an area of approximately 730 square miles. Its shape. is roughly that of a circle with a diameter of 30 miles. The lake occupies a shaI:ow depression the lowest part of which is approximately at sea level. The total tributary area, including the lake surface, is about 5,200 square miles. Of this total the Kissimmee valley accounts for 3,079 square miles. Prior to the construction of drainage works, the lake overflowed into the Glades when the stage reached an elevation of about 21 feet. Before the opening of the St. Lucie Canal in 1926 the recorded stages varied from 13.8 to 21.7 feet. Since that time the range has been from 11.8 to 19.5 feet and the average stage has been approximately 16.0 feet. The lake is now regu'ated through two outlets. The St. Lucie Canal to the Atlantic Ocean has a capacity of 5,000 second feet at a 17-foot lake stage, and the Caloosahatchee Canal to the Gulf has a capacity of 2,500 second feet. The combined capacity of the two outlets is sufficient to lower the lake about one foot from normal level in 30 days. The lake is now regulated by the United States War Department and the stages are held as nearly as possible between 14 and 17 feet. A levee has' been built a'.ong the east and south sides of the lake, extending from the St. Lucie Canal to Fish-eating Creek, a distance of about 50 miles. An additional 15 miles of levee also has been built at the north end of the lake near Okeechobee. The elevation of the levee top varies from 34 to 36 feet. This levee will be a protection against huge waves caused by hurri canes. The Florida Everglades contains about three-fourths of the

PAGE 9

Water Control in th e Soils of th e E ve rglades 9 peat lands of the state and is probably the largest continuous body of peat in the world. It is primarily a great sawgrass marsh covering about 4,000 square miles. It lies in a trough about 40 miles wide by 100 miles in length that extends from Lake Okeechobee almost to the end of the peninsula and is bounded on either side by a low sandy ridge. The slope from north to south is about two inches per mile. The elevation near Lake Okeechobee is now about 16 feet above mean low tide. Prior to drainage, this great peat area was wet during a large portion of the year . The overflow from Lake Okeechobee to gether with the normal rainfall of about 54 inches per year and some run-off from the higher lands on either side resulted in a high water table which conserved the soil and permitted a slow increase in depth of peat from year to year. The depth of peat varies generally from north to south. Near the east side of Lake Okeechobee it is 8 to 12 feet deep but in the southern portion of the Glades it is quite shallow. The depth over a large part of the area is now less than three feet, and probably not more than 500,000 acres has a depth of more than five to six feet. Approximately 85 , 000 acres of the peat and muck lands of the northern Everglades are now in agricultural use. About one fourth of thi s is in s ugarcane and most of the remainder is used for truck crops. Nearly all the cultivated acreage is served Fig. 2.-Limerock under peat along the North New River Canal near South Bay.

PAGE 10

10 Florida Agricultural Experiment Station by pumps. In addition to this there are about 20,000 acres in cultivation near the southeastern edge of the Everglades and approximately one fourth of this acreage is in citrus groves. The peat depth in this part of the Everglades is very shallow and only a small portion of the land is served by pumps. A considerable portion of the Everglades area is underlaid with a more or less porous deposit of limestone and marl con taining marine shells. This is known as the Fort Thompson formation. It underlies the area adjacent to Lake Okeechobee and extends south to about Twenty Mile Bend on the North New River Canal. West of the Palm Beach County line a layer of sand is usually found between the peat and the rock. Most of the re maining portion of the area is underlaid with Miami oolite. This is a white limestsone which is considerably more porous than the Fort Thompson formation. The underlying rock formation along the North New River Canal near South Bay is shown in Figure 2. This picture was taken when the water had been pumped from a section of the canal in order to excavate rock for a new road. SOILS OF THE EVERGLADES The soils of the Everglades usually have been divided into three general types called "custard apple," "willow and elder," and "sawgrass." According to a recent classification and survey these three general types are to be known as Okeechobee muck, Okeelanta peaty muck, and Everglades peat, respectively. There are some finer distinctions and a few other types, but this general classification will be adhered to in this report. By far the greater portion of the peat soils of the Everglades is composed of the partially decomposed remains of sawgrass. The marshy condition of the Glades, during the period of forma tion, prevented a more complete decomposition of this material. In its original condition the sawgrass peat is a brown fibrous mass in which the partially decayed sawgrass roots can be readily distinguished. These roots are approximately in a vertical posi tion. After drainage, cultivation and weathering gradually transform the top soil into a condition approaching a true muck. The structure then changes into an amorphous mass, the density increases, the color becomes dark, and the rate of seepage through the soil is retarded. When saturated the soil is a little heavier than water. After

PAGE 11

Water Control in the Soi/,$ of the Everglades 11 drainage, the water retained by the soil is equivalent to about three-fourths the weight of the field sample. The oven-dry weight of the soil below the normal water table is about eight pounds per cubic foot of field sample, and the ash or mineral content is about 10 percent of the dry weight. The oven-dry weights of the upper 18 inches of soil, from fields in cultivation for 10 to 15 years, indicate that the density about doubles after a considerable period of intensive use. In December, 1935, soil samples were taken from 16 locations within a 10-acre field at the Everglades Experiment Station. The figure for each six inches of depth, as shown in Table 1, is an average of 16 samples taken with a brass cylinder six inches long and four inches in diameter. The field has been drained for the past 20 years but had been in cultivation only two years before the samples were taken. At a depth of 13 to 18 inches is a thin layer of slightly plastic, peaty muck, but the remainder of the soil is typical sawgrass peat. TABLE 1.-OVEN-DRY WEIGHT AND ASH WEIGHT OF SOILS AT EVERGLADE S EXPERIMENT STATION. Depth of I Oven-Dry Weight I Ash Weight Ash to OvenSample per Cu. Foot per Cu. Foot Dry Weight Inches I Pounds I Pounds P e rcent I 0-6 17.5 1.76 10 . 1 7-12 12.2 1.27 10.4 1 3 -18 11.4 2 . 00 17.5 19-24 9.5 1.14 12.0 25-30 8.1 0.68 8.4 3 1-36 7.5 0.62 8.3 37-42 7.8 0.70 9 . 0 43-48 7.7 0 . 73 9 .5 Average 10.2 1.11 10 . 6 The large ash weight for the 13 to 18 inch depth is due to the thin layer of peaty muck. If the samples for this depth are omitted the remaining samples of sawgrass peat show an average ash weight of approximately 10 percent of the oven-dry weight. The greater dry weight of the upper portion of the soil shows the effect of compaction, weathering and oxidation as the saw grass peat is slowly changed into a condition approaching a true muck. It is probable that the water table in this field has aver aged about 24 inches and has seldom been lower than 30 inches. The samples below the normal water table show little difference in dry weights.

PAGE 12

12 Florida Agricultural Experiment Station TABLE 2.-SOIL SAMPLES ON SUBSIDENCE LINES-APRIL, 1938. Results Ba s ed on One Cubic Foot of Field Samp . e. Moist Oven-Dry Ash Water in Depth We ' ght Weight Weight Moist Soil /Ash in Oven Dry Soil Inches Pounds Pounds Pounds Percent I Percent I Line A 1-6 37.4 9.4 1.41 75 15.0 7-12 43.7 6.!) 0.69 84 10.0 13-18 54.9 9.6 1.26 83 13.1 19-24 63.3 12. 3 2.08 81 16.9 25-30 60.7 9.8 1.35 84 13.8 31-36 5 9 . 7 8.1 0.94 86 11.6 37-42 6 3 .4 7 . 8 0.90 88 11.6 43-48 65.2 8.6 0.95 87 11.0 Line H 1-6 59.8 23.0 2.78 62 12.1 7-12 64.6 14.4 1.90 78 13.2 13-18 62.9 10.9 1.37 83 12 . 6 19-24 64.1 12.4 2.53 81 20.4 25-30 62.2 8.8 0.86 86 9.8 31-36 64.1 7.6 0.79 88 10.4 Lawn 1-6 57.2 14.8 2.46 74 16.6 7-12 61.8 12.6 I 1.75 80 13.9 13-18 62.9 10 . 3 I 1.35 84 13.1 19-24 64.6 12 . 9 2.54 80 19.7 25-30 62.5 8.6 0.76 86 8 . 8 31-36 63.1 7.4 I 0.72 88 9.7 ~ .. . --I ~ --. Remarks Line "A" in Sec. 10 at Everg!ades Experiment Station. Virgin sawgrass soil. Water table approximately 3.5'. Line "H" at Everglades Experiment Station near Well 12. Sawgrass soil in cultivation since 1924. Line over grass lawn at Everglades Experiment Station. Sawgrass soil. Table 2 shows three sets of soil samples taken from lands at the Everglades Experiment Station in April, 1938. The high ash content of the 19 to 24 inch sample in each set is due to the thin layer of peaty muck referred to above. Line A is on virgin sawgrass soil, south of the Experiment Station. Line H is on land which has been in truck crops for about 14 years and the "Lawn" line is on soil which has been covered with St. Lucie grass for nearly the same period. The Okeechobee (custard apple) or plastic muck of the Ever glades covers about 30,000 acres located along the east and south sides of Lake Okeechobee. It is thought to have been formed from the residue of succulent water plants deposited during a period when the area was continuously under water. The ash or mineral content varies from approximately 35 to 70 percent of the oven-dry weight. This soil is dark in color and homo

PAGE 13

Watel' Control in the Soils of the E verg lad es 1 3 geneous in struct ure . It was commonly called "custard apple" muck on acco unt of the custard apple trees which originally covered it. The proximity of this soil to the lak e probably accounts to so me extent for the high mineral content. In its original state this soil was l ess fibrous and contained more of the elements essential to plant growth than did the sawgrass peat. Hence it was the first of the Everglades lands to be used since it was also somewhat higher a nd therefore had better natural drainage. TABLE 3.-SOIL SAMPLES ON SUBSIDENCE LINES--APRIL, 1938. Results Based on One Cubic Foot of Field Samp:e. Moist Oven-Dry Ash Water in I A s h in Oven Depth We ; ght Weight W e ight Moist Soil I Dry Soil Inches Pounds Pound s Pounds Percent Line s 1-6 54.2 18.4 5 .46 66 7-12 55.3 17.7 4.11 68 13-18 63.8 17.0 7.80 73 19-24 66.0 18.0 8.19 73 25 30 65.3 1 3 .2 3.54 80 30-36 63.1 9.6 1. 3 4 85 Line 0 1-6 47.2 27.5 14 .85 42 7 12 40.6 15.3 7.19 62 1 3 -18 47.6 14.3 7 .1 2 70 19-24 55.6 18.0 11. 35 68 25 3 0 62.0 24.3 18. 30 61 31 36 69.4 24.6 1 5.15 65 Lin e E 1-6 52 .2 31.7 15.88 39 7-12 60 .9 28.2 19.38 54 13-18 55.5 23.6 17.04 58 19-24 59 . 4 23.4 16.31 61 25-30 61.8 1 9 . 3 10.81 69 3 136 60 . 8 13.6 2.82 78 37-42 70 . 8 11.1 1.55 82 43-48 63. 1 9 . 1 0.96 86 Lin e D 1-6 58.4 41.7 26 .5 2 29 7-12 53.6 24.1 15.91 55 13-18 54.2 20.8 1 3.40 62 19-24 56.1 18.7 12.29 67 25 30 64.1 15.6 7.80 76 31 36 69 .8 16.0 10.53 77 37 42 70.4 18.4 10 . 30 74 43-48 72.8 18.0 12.22 75 Remarks Line S near Well 1 8 a t Canal Point. Willow and elder soil. Line O near Well 7 at Canal P oint. Okeechobee muck. I I I I Lin e E at W e ll 10 on Boe farm near Pahokee. Okeechobee muck. Line D at Well 8 near Bean City. Okeechobee muck. Percent 29.7 23.2 45.9 45.5 26.8 14.0 54.0 47 . 0 49.8 63 .1 75 .3 61.6 50.1 68.8 72.2 69.7 56 . 0 20.7 14.0 10.5 63 .6 66.0 64.4 65.7 50 . 0 65.8 56.0 67 . 9

PAGE 14

14 Florida Agricultural Expe ' riment Station The samples from Lines 0, E and D as shown in Table 3 are typical Okeechobee (custard apple) muck. The low ash content of the bottom 18 inches of soil on Line E is due to a layer of sawgrass peat. At a depth of 25 to 30 inches on Line 0, and 13 to 18 inches on Line E, a two or three inch layer of yellow and grayish material was encountered. Tests showed this to be ash; hence the high mineral content of the samples at the above depths. Such ash deposits found in this location and elsewhere in the Everglades indicate that destructive fires occurred in this area in the distant past. Between the Okeechobee muck and the Everglades peat is an intermediate soil type, Okeelanta peaty muck, commonly called "willow and elder" land. This is somewhat similar to the saw grass peat but has a higher ash content and usually a thin, well defined layer of plastic muck within the top two feet of the profile. The zone of Okeelanta peaty muck is not clearly defined but probably covers about 40,000 acres. Line S, shown in Table 3, is on soil of this type. In addition to the three types of soil previously mentioned there is a substantial area of Loxahatchee and Gandy peats. The former type was formed from a mixture of sawgrass . residue and other vegetation, including water grasses and lilies, and largely comprises the so-called "slough areas." These areas are usually quite wet and are probably best suited for wild life reserves. There is a large body of this land along the east side of the Glades Fig. 3.-Shrinkage of organic soils. Center cylinder shows original size. Sample on left is Everglades peat; sample on right is Okeechobee (custard apple) muck.

PAGE 15

Water Control in the Soils of the Everglades 15 between the Hillsboro and West Palm Beach canals. The latter type is composed of woody material derived from various species of bay and myrtle, and occupies the small islands and ridges commonly associated with the sloughs that are made up of the Loxahatchee type. Peat soils are subject to much shrinkage when dried and will not expand to original volume when water is again added. Figure 3 shows two soil samples which were oven-dried. The center cylinder shows the original size of the samples. The one on the right is Okeechobee (custard apple) muck; the one on the left is Everglades peat. SUBSIDENCE OF PEAT SOILS As the subject of subsidence in the Everglades has been cov ered in special reports, 3 only a summary will be given here. Peat soils are formed by the slow accumulation of plant resi dues under very wet conditions.J The complete decomposition of the plant material is prevented by the high water table usually found in swampy areas. After the natural water table is lowered by drainage the ground surface elevation begins to fall. This subsidence is due to loss of water and to slow oxidation; also to compaction of the top layer by cultivation. After a virgin area is drained the subsidence is very rapid at first, but decreases with time. Figure 4 shows the rate of sub sidence along a reference line near Okeelanta, Florida. A small portion of the loss shown is due to fires, but by far the greater portion is due to subsidence resulting from drainage. Most of the cultivated lands of the northern Everglades have subsided approximately five feet since drainage was begun about 25 years ago. The rate of subsidence of sawgrass soil, in recent years, has averaged about one inch per year. Okeechobee (cus tard apple) muck subsides at a somewhat slower rate. A large number of reference lines have been established in the northern Everglades for a continued study of this subject. The data so far available indicate that the rate of subsidence is approximately proportional to the average depth of water Clayton, B. S. Subsidence of peat soils in Florida. Bureau of Agri cultural Engineering. U.S.D.A. Report No. 1070, 1936. (Mimeog.) 'Allison, R. V., 0. C. Bryan, and J. H. Hunter. The Stimulation of plant re s ponse on the raw peat soils of the Florida Everglades through the use of copper sulphate and other chemical s. Florida Agr. Exp. Sta. Bul. 190: 33-80 . 1927.

PAGE 16

16 Florida Agricultural E x periment Station Fig. 4.-Surface subsidence of Okeelanta peaty muck near the Bolles Canal. table. 5 As the lowering of the water table exposes a greater volume of soil to slow oxidation a greater subsidence loss nat urally occurs. Total subsidence following drainage does not appear to have been much affected by the type of crop grown, as lands p'.anted to cane, truck crops, or grasses have subsided approximately the Bame total amount. Even virgin lands exposed to pump drainage or near the large gravity canals have subsided about four feet. A large number of soil samples have been taken from various reference lines. These have been oven-dried and the density and ash content determined. The results indicate that the top 18 inches of soil on fields used intensively for truck crops has doubled in density in about 10 years of use. The soil densities, based on oven-dry weights, decrease from the top downward. In virgin soil areas which have subsided almost as much as the cultivated fields, the density of the top soil shows very little increase over that below the permanent water table. For equal subsidence a greater loss of soil mass has occurred in the drained but idle lands. It, therefore, appears evident that the land should be placed in cultivation as soon as possible following drainage in order to conserve the soil. " Roe, H. B. A study of influence of depth of ground wat e r level on yields of crops grown on peat lands. Minn. A g r. Exp . Sta. Bui. 330: 1-32 . 1936.

PAGE 17

Water Control in the Soils of the Everglades 17 Much of the virgin land in the northern Everglades has sub sided from three to four feet due to gravity drainage by the large canals and there has been little or no increase in density in the upper portion of the soil. Subsidence levels over similar saw grass land near Pahokee show that after pump drainage was established and the area was planted to cane a further subsi dence of 1.8 feet occurred during 10 years of use. It is probable that approximately an equal amount of subsidence will occur during the next 20 years, making the loss after 30 years of use about 3.6 feet. It is, therefore, important that before new areas of virgin lands are brought into use, the depth of soil and prob able subsidence should be carefully considered in planning the drainage works. From the records avai 1 able it is estimated that the average water table in the cultivated lands of the northern Everglades is approximately 2.5 feet. This may vary from surface to a depth of four feet, due to the variation in season, rainfall and the amount of pumping. If the water table were held to an average depth of 1.5 to 2.0 feet, the subsidence would be propor tionally reduced. Aside from maintaining a higher water table, there appears to be no practical way of decreasing subsidence in peat soils. SEEPAGE THROUGH PEAT SOIL There is considerable evidence that the seepage movement in the Everglades is largely through the porous rock and sands beneath the peat. Typical profiles of the water table between drainage ditches approximate a rather flat curve over the major portion of the line, but about 100 feet from the ditches the pro files show a steep slope, indicating the resistance of the peat to lateral seepage. In porous material like sand the slope would be much flatter. It was also noted that the completion of the new lake levee, with the probably impervious seepage fills be neath, apparently had no substantial effect on the ground water table of the protected lands. In the spring of 1939 the water in the North New River Canal was a foot or more below the rock over a long stretch below Okeelanta. Well readings on the west side of the canal showed a water table slope towards the canal for a distance of at least two miles back (Fig. 5). From the canal to a point a half mile back, the seepage gradient rose approximately two feet. It was thus evident that the seepage water from the peat lands on either side reached the canal through the porous rock formation.

PAGE 18

o,oo 10,00 20 :!,Q,00 Lin e 2 mil e s south of Bolles Conol west trom 1-r 19hwoy No 26 wote, Jobi e ele,otions mo,~ed wS Line 4 m,ies sou!h of Boll e s Coocl w e st from Highwoy No. 26 Weier Tobie tlevotio~s morktd WS 90.00 90,00 Fig. 5.-Profiles showing water table in virgin peat land after a very dry 'period. 00

PAGE 19

Water Control in the Soils of the Everglades 19 Figure 5 shows surface profiles and water tables along two lines. One begins at the North New River Canal two miles below the Bolles Canal near Okeelanta and the second begins four miles south of the Bolles Canal. Both lines extend two miles to the west over sawgrass land. The depths to water table were very close to maximum, as the rainfall for the preceding year was one of the lowest recorded. To make a rough comparison of the rates of seepage through vertical and horizontal sections of sawgrass peat, three samples were taken in brass tubes four inches in diameter. One vertical sample was taken from the top 18 inches of soil, a second from the 18 to 36-inch depth, and a horizontal sample was taken at a depth of three feet. The land has been drained by pumps for 14 years but has been in cultivation for only a few years. The vertical samples were 18 inches long. The horizontal sample after compression of several inches due to forcing the tube through the soil was 11 inches long. The tubes were set up so that the difference in level of the inflowing and outflowing water was held constant at 19 inches. The average depth of water passing through the top 18-inch sample was 0.30 foot per day, that through the 18 to 36-inch vertical sample was 27.3 feet and that through the horizontal sample was 0.25 foot per day. The second vertical and the hori zontal samples were both in the brown fibrous peat, and the wide difference of seepage movement through them doubtless is due to the structure of the partially decayed sawgrass residue which provides small openings along vertical lines. The seepage through the top sample of soil was not much greater than that through the horizontal one. The top soil is changed by weather ing and cultivation into a very finely fibrous peat. The density is increased and the original vertical seepage lines are largely obliterated. Hence the decrease in rate of seepage movement. This change is evident in old cultivated fields for, subsequent to a heavy rain, surface water remains for extended periods after the ditches are pumped to a low level. The rates of seepage through the samples were doubtless af fected to some extent by compaction. However, the differences were so great that it seems reasonable to conclude that the seep age movement through the soil is much greater in a vertical than in a horizontal direction.

PAGE 20

20 Florida Agricultural Expe1"iment Station CLIMATOLOGICAL DATA RAINFALL On the peat lands near Lake Okeechobee there are four rain fall stations with records of more than 14 years. These are located at Canal Point, Moore Haven, Everglades Experiment Station, and the Shawano Plantation. Also, there was a record at Ritta from 1914 to 1930, inclusive, but this station was dis continued in 1930. Ritta was located on the south shore of the lake about two miles west of the Miami Canal. The Station at Canal Point is maintained by the Cane Breed ing Experiment Station of the U.S. Department of Agriculture; the one at Moore Haven by the U. S. Weather Bureau; and the one at Shawano by the Brown Company. Tables 4, 5, 6 and 7 show the monthly and annual rainfall for the four stations. Maximum, minimum and average monthly and annual rainfalls also are shown. The average rainfall for the four-month period from June to September at the Everglades Experiment Station is 60 percent of the mean annual precipitation and at the other three stations it is 59 percent of the annual amount. December is the driest month at each of these stations, with an average of about one inch. Two of the longest rainfall records in South Florida are those at Fort Myers and Miami . A 70-year record at Fort Myers, including 1938, shows a mean annual precipitation of 51.84 inches, a maximum of 82.64 inches, and a minimum of 32.85 inches. At Miami a 51-year record shows a mean annual of 59.51, a maximum of 89.07, and a minimum 33.15 inches. The record shown for the Everglades Experiment Station covers 14.5 years. The maximum rainfall for a calendar year was 66.14 and the minimum was 40.99 inches. However, the maximum rainfall during a consecutive 12-month period was 73.81 and the minimum was 34.98 inches. Table 8 shows the record of excessive precipitations at the Everglades Experiment Station for the years 1935 to 1938, as determined from the charts of a weighing rain gage. On'.y 15 storms of two inches or more were recorded during these four years. The greatest rate for one hour was 3.25 and that for two hours was 3.35 inches. The Weather Bureau record at Miami for the period 1912 to 1930 shows a maximum of 3.50 in one hour and 6.11 inches in two hours. These Miami records were obtained from November storms.

PAGE 21

.. y eai I ,Ja n. I ! HJ2:J I l.5:~ 1i124 :m o 1 !12 ,:i 4.4G 11J2(; G. Ul 1!127 0.8 : l l\l28 0.l!J l!l2\l 1. : H 1!J;)() 2.54 l\l:.1 1 2.05 l!J : {2 0.26 l!l3:l 1.54 1!134 0.25 l!/ 85 0.16 rn:rn 2 . 40 .U1:l7 4.30 l!);J8 0. 1 2 Av. M ax. lv 1 i n . U 1 2 6.19 0.12 F eb . 0.14 2.23 2.24 2.25 1.80 1. 38 O.D7 3 . 03 0.9 1 2.38 0 .35 5 . 36 2.8 1 5.6 9 1.81 0.84 2.08 5.69 O.D7 0. 34 3.71 2 .46 1.63 2 . 87 3 .4 8 0.60 4.32 4.27 0.87 4.n 2 .77 0.17 3.27 4 . 88 1. 08 2 . 56 4. 88 0 . 1 7 T AB L E 1 2 3 3 1 1 2 !J 5 2 6 7 5 0 3 0 3 9 0 .55 .1 7 .5 0 .33 .08 . 7 2 .32 .25 .71 . 67 . 42 . 64 .45 .39 . 36 .45 . 56 .25 .39 -. 4 .-RAIN FA LL IN INCH ES A T CANA L POI N T . M a y ! Jun e I J ul y I A u g. 1 1 Sept. I I 7 . 06 2.27 9.73 1.54 1.54 3 .10 5 . 4 3 1 6.1 0 1 3.05 3 . 49 1 1. 3 1 6.27 0.76 6 .10 1 1.92 3. 13 3.93 9.73 1 0.76 6 . 62 4.84 8.62 8.62 6. 3 1 5.4 2 1. 74 6 . 96 0 .4!J 1. 26 7 . 62 7 . 96 6. 11 4.W 4 .44 6.67 , -8 . 48 \ !J . !J 5 1 1. 08 I 1.85 8.47 ' 7 . 12 7.-15 5 .7 2 7.32 8 . 14 14.57 14 .1 3 11.26 6 . 31 4.08 3.07 3.33 4.67 -E ll 9.9 1 1 1.02 8.51 5.20 8 .1 4 3 . 98 3.62 5.44 8.59 14 . 62 9.37 7.28 5.52 8.00 8.22 7.16 6.96 14.62 1' 14. 1 3 0.4 9 3.3:~ 1.85 _ _ _ _ __ ) _ _ _ _ 8.31 10.[)7 4.0\J 14.82 3.:H 1 6 .4 5 10 . 70 5.3 6 5.64 2 . 4 0 8 .1 6 11. 6!) 11. !J O 4.08 5 . 8 8 8.45 8.26 16.45 2.40 ;3.17 1 8 . 14 2. 25 1. 24 3 . :15 0.77 :;,08 5.14 4.43 4.51 4.36 2.40 * 4.44 2 . 84 6.50 :3 . 69 4. 39 1 8 . 14 0 . 77 40 R a infal1 for mo n th es t i m ated from l'C co 1d s of n earby sta t ions. 0.43 0.8!) 1. 6 7 0. 7 2 0.4!) 1.24 0.69 0.67 0.70 25.09 1.84 0.55* 0.57 5.08 2.23 0.!-J7 2. 7 4 25.09 0.43 0.45 0.15 UJ!J 0.10 0.40 0. 20 1. 08 2.77 4.62 0.16 O. O !J 0 .58* 1.22 1. 65 0. 26 0 .10 O.!J9 4.62 0 . 09 4 8. 0 3 61. 3 0 56.60 5 3 . 6 1 :16.44 6 2.65 54 . G2 6 3.2!J 39 . 87 67.9 1 58.95 58.81 4 1.1 9 59.82 59 . 57 3 8 . 30 53.81 67 .91 3 6.44

PAGE 22

T AB LE 5. -RA INFA LL IN INCH ES A T MOO RE H AVE N. Yea r Jan . Feb. Mar . I Apr. I May I I I I J une Ju l y j A u g. I Sept . ; Oct . I ! i i I 1 918 I 2.05 0 . 35 2 . 55 2.87 6 . 94 1 0. 83 2 . 72 1 9 19 1.25 3 . 7 0 2 .83 0 . 62 6.7 0 1 0 .59 6 . 88 I 4. 1 2 2 . 78 0 .90 19 20 2 .10 2.5 9 0. 53 5 . 13 3 . 05 6.8 4 1 5 .21 4 .51 3.1 8 2.72 1 92 1 0.45 1. 99* 0.8 4* 0 . 66''' 5.86* 2. 1 6* 5. 1 1"' 3.65* 2 .1 6* 8.35 1922 0 . 7 0 1.1 0 0. 74 0.46 5.14 9 . 82 7.63 6.72 14 . 93 1 0.70 1923 0.32 0.4 9 0. 62 3 . 55 1 1.70 12.52 7 . 5 4 10 .0 4 4. 23 1. 39 192 4 3 .05 1.7 5 3. 38 3 . 55 1. 21 8.86 1 1.77 4. 76 8.41 13. 39 1925 2.2 1 1. 88 2.04 3.92 6.43 8.69 4.68 9.83 1. 08 1. 54 1 92 6 3.49 1.1 9 1.1 2 3.82 2.13 15. 0 5 11 . 24 6.24 8 . 90* 1. 93* 19 27 0.11 2.0 9 1.70 2.0 2 1.94 10.79 5. 79 8 .61 6.9 9 4. 12 1 92 8 0.4 2 2 . 3 1 2 .46 1. 52 4.19 8. 1 2 5.43 11.82 1 4 .6 0 0 .47 1 929 0.82 0 .1 4 0 . 52 1. 55 2 . 73 9.35 8.44 4 . 93 1 3.45 1. 71 193 0 0.49 3 . 23 4.76 4.12 1 1.33 17 . 85 4.72 11.6 1 1 1. 26 6 . 33 1 93 1 2 .58 0.7 6 5. 9 0 3.4 4 1.59 1. 2 0 2. 68 10.34 5.0 6 1. 94 1 932 1. 97 3. 1 3 2. 87 1. 76 6.05 4.96 6.2 5 15.71 5.99 2 .93 1933 1. 65 0 .1 9 3 . 88 6.92 3 . 89 4 . 66 5.36 5.77 2 . 75 5 .1 8 193 4 1. 33 2 . 89 2. 73 2.22 6.43 4.36 8.48 6.2 0 4 .1 8 5 . 54 1 93 5 0.52 1.00 0.0 3 5 . 1 8 3 . 57 5.8 4 5 .09 5 .50 9.5 3 1. 42 1 936 2.23 4 . 9 7 1. 95 2.55 5.41 14 . 59 2.99 5.79 11. 5 1 3 . 55 1 937 2 .0 7 1. 70 4 . 83 I 4.89 4.94 3.59 13 . 79 4.7 1 4 . 48 8.72 1 93 8 0 .61 0.5 7 0. 34 0 . 2 1 6.28 7.4 0 8 . 2 0 2 . 39 2. 23 3 . 92 Av. 1. 42 1. 88 2.20 2.86 4 . 81 8 . 08 7. 1 5 7. 1 5 7.05 4 . 26 Max. 3.49 4.97 5. 90 6.92 I 1 1.70 1 7.85 15.2 1 1 5.71 1 4 . 93 1 3 . 39 Mi n. 0.11 0.14 0.0 3 0 .21 0.35 1.2 0 2 . 6 8 2 .3 9 1.0 8 0 .47 * R a i nfa ll fo r month esti m ated from records of nea r by stations. Nov . I D ec. I 0 . 98 0.73 4 . 86 1.1 5 4 .5 4 0 .63 2 . 1 9 0.25 1.56 0 .89 0. 2 1 0 . 28 0 .3 0 0. 0 9 0.93 2 . 83 1 .74* 0 . 10 0. 38 0 . 39 0 .97 0.3 1 1. 2 7 1.39 0 .45 2 . 33 0. 08 0 .3 5 3.28 0. 0 7 0 .92 0 .28 3.58 0.26 1.71 1. 48 0 . 58 1.1 8 5.47 0. 44 1. 52 0 . 11 1.7 9 0 .74 5 .47 2 . 83 0. 08 0.0 7 An nual Total 4 6.38 5 1.0 3 33 . 6 7 60.39 5 2.8 9 6 0.52 46. 06 5 6 . 95 44.9 3 5 2.62 46 . 3 0 78 .4 8 3 5.92 54 .97 4 1.45 48 . 20 40.87 57 .30 59 .6 3 33 .7 8 5 0 . 1 2 78 .4 8 33 .67

PAGE 23

TABLE 6.-RAINFALL IN INCHES AT THE EVERGLADES EXPERIMENT STATION. Year Jan. Feb. 1 1 Mar. I Apr. I M:;--/i ~J-u-ne I July i Aug. i Sept. / Oct. / Nov. I Dec. I Annual ------~I I __ J I I ___ ___,_ __ ______c __ T_o_'._al_ 1 6.5 3. 72 I 8.49 1924 I 1925 I 1926 I 1927 1 11 1928 1929 1930 I 1931 1 1 1932 1933 1 1 1934 1935 I 1936 I 1937 I 1938 11 1 Av. Max. I Min. I 3.58 5.39 0.32 0.31 1.20 1.92 2.31 1.72 0.64 0.14 0.30 1.91 2.97 0.46 1.65 5.39 0.14 2.4 2.37 3.78 9.38 5.61 5.56 12.:36 4.17 o.66 1.4s 1.81 3.69 9.29 10.57 10.40 I rn.60 2.90 2.18 2.44 3.19 1 .08 12.11 11.45 I 6.41 1.66 3.83 1.78 2.61 9.20 8.25 I 1.31 I 19.04 0.49 1.70 2.61 8.92 11.11 7.32 :J.7!) 12.23 2.40 6.32 6.03 4.43 19.61 6.28 :J.74 3.58 I 1.17 3.93 4.41 3.16 0.59 3.05 7.67 110.68 2.13 1.56 1.54 4.69 16.01 3.93 10.5!) 7.43 0.38 5.42 6.90 4.04 9.51 3.85 12.75 11.89 1.91 7.10 3.11 5.20 10.15 10.0H 12.41 7.44 1.32 0.41 5.32 1.08 8.45 6.37 6.54 10.88 4.04 2.40 I 1.96 6.39 18.61 6.09 5.33 5.84 1.21 5.87 6.00 3.38 7.74 7.65 7.89 8.35 i 1.14 1.87 0.32 4.52 5.44 8.85 2.65 10.09 I 1.71 3.32 3.43 4.62 9.89 7.15 8.17 9.34 I 4.04 7.10 6.90 9.38 19.61 12.77 12.75 19.04 0.38 0.41 0.32 1.08 0.59 3.05 2.65 3.58 I 15.84 0.49 3.58 4.50 1.46 4.71 4.94 4.16 3.68 5.30 3.22 5.71 1.65 4.92 I 2.78 I 4.46 15.84 0.49 0.62 1.14 0.91 0.42 1.07 4.13 0.56 0.51 12.36 4.50 0.65 0.36 9.17 2.08 2.66 2.74 12.36 0.36 0.22 2.84 0.55 0.42 0.25 0.92 3.54 1.11 0.50 0.12 0.82 2.07 1.18 0.38 0.21 1.01 3.54 0.12 53.77 61.93 54.08 60.77 59.13 63.35 42.75 66.14 65.30 62.24 48.81 64.57 58.44 40.99 57.30 66.14 40.99 N) c.,:,

PAGE 24

TABLE 7.-RAINFALL IN INCHE3 ON THE SHAWANO PLANTATION. Year Jan. Feb. I Mar. I Apr. I May I June I July Aug. Sept. Oct. Nov. I, ! i I I 1925 I 7.38 2.42 0.63 3 . 84 1.71 1926 I 4.86 I 1.29 1.48 3.24 3.41 5.85 5.64 12.02 6.64 4.58 I 1.45 0.43 50.89 1927 i 0.37 I 1.72 1.82 1.55 3.14 4.94 5.19 8.16 4.91 3.58 0.51 I 0.60 36.49 1928 I 0.83 0.25 2.18 6.74 4.90 8.16 5.27 14.66 16.48 ! 1.08 I 1.05 0.44 62.04 1929 I 0.46 I 0.78 2.08 2.68 6.18 6.64 7.51 5.66 10.43 6.20 I 2.92 1.73 53.27 1930 1.33 2.29 5.09 5.36 3.54 9.03 3.20 2.83 6.14 2.47 I 0.96 2.00 44.24 1931 I 2.61 0.98 4.29 5.00 2.63 1.20 4.65 8.32 I 9.31 5.29 0.96 0.54 45.78 1932 I 2.10 0.99 2.28 0.99 5.02 8.45 2.06 10.83 4.00 4.11 5.64 0.15 46.62 I I 1933 I 1.02 0.19 3.11 4.51 2.01 6.52 10.36 8.59 I 8.03 11.30 3.17 0.30 59.11 1934 I 0.56 1.09 4.38 3.15 6.41 5.07 9.77 9.85 I 5.14 2.01 0.54 2.13 50.10 ' 1935 I 0.61 0.78 0.64 7.28 1.59 10.13 4.13 11.36 I 12.81 6.11 0.61 I 3.01 59.06 1936 I 2.06 I 4.16 3.48 0.57 3.69 17.72 8.19 5.47 ! 5.03 4.46 5.24 1.49 61.56 1937 I 2.45 1.08 5.27 3.42 4.40 7.13 13.37 2.00 I 10.45 4.25 1.45 0.44 55.71 1938 i 0.49 1.95 1.43 0.00 5.25 8.18 8.20 3.73 I 6.72 1.81 1.77 0.39 39.92 I I i Av. I 1.52 1.35 2.89 3.42 4.01 7.62 6.73 7.92 I 7.75 I 4.13 2.15 1.10 51.15 Max. I 4.86 4.16 5.27 7.28 6.41 17.72 13.37 14.66 I 16.48 11.30 5.64 3.01 62.04 Min. I 0.37 0.19 0.64 0.00 1.59 1.20 2.06 2.00 I 2.42 I o.63 0.51 0.15 36.49 I

PAGE 25

Date ( i / 25 / :{!'i 8 / \l / :{!'i G / l ii /: lG 11 / (j / ; l(j 11 / 12 / :36 1/13/87 ;J / 3 1 / :17 t / (i / : fi G / 8 / :i'i 7 1 1 1 :r, !! / 5 / :r , !l / 2 / :3H TABLE 8.-EXCESSIVE PRECIPITATION AT THE EVERGDES EXPERIMENT STATION 1935 TO 1938, INCLUSIVE. A c cumulated Am o unts of Rain fall (in Inche s) During Period s ii Highest Amount (in Inches) ~ _ l _ h_r_. _ _ _ 2_h _ rs. ~rs. 0 .94 0.56 f 0.o7 { 0.62 l 1.16 2.10 f 0.11 { 1.80 [ 3.24 f 0.10 ( 1.71 I 0.10 ) 1.88 0.10 0.10 \ 0 .98 ( 4.6 3 0.58 2.10 { 0.24 2.50 2.40 2 .26 3. 00 1. 95 0.11 O.!lO 1.23 2.45 o. :l8 2 . 12 3. 70 0.10 1.74 0.12 1. 96 1.25 0 . 14 UJG 4.68 0.58 2 . 26 0.80 2.G5 3 .73 1. 97 0.1 8 0 .9 2 1.3 3 2.6 2 0.62 2.44 4.11 0 .10 2.24 0.17 2.00 3.45 0 .84 2.25 0 .73 2.37 0. 8 0 2.32 2.38 4 hr s . 3.84 2.00 0.18 0.95 1.50 0.82 2.52 4.14 0.20 2.45 0.30 2.07 1.40 2.58 1.37 2.44 0.32 5 hrs. 0.21 0.D7 I.GI 11 . !:k 2 ,(i(i 1.18 0.20 2.fJ2 ().:l] 2.0!1 1.77 :J.! 12 0.70 6 hr s . ----0.2:l 1..1 :1 l.5 2 1.08 2.85 t.22 0 .2 2 2. :i4 o.: 3 1 2 . 10 1.78 , Ul6 ].] !I 7 hrs. I 8 hrs. JL .. I .. ii 1 hr . I 2 hr s . 0.42 l.1 (i 1.8:J 1.17 :J,00 5.38 0.22 2.7!1 1.10 2.10 2.14 Ui0 :i.:38 2.20 0.60 1.16 2.01 1.43 3 .10 G.55 0.82 :l.05 urn 2.12 4.50 :J. 84 2.42 ,1 (I f i :i i\ !1 ii 11 I ' ii Ji ,. 11 1 , 2.54 2. 10 I.IG I : uo 2.45 2.83 :1.35 2.26 I i 2.40 2.65 I 2.2(j 2 . 32 :i _____ __ _ I _ _ _ _ _ _ Noll• --H a in ~ of l ess tha n ~.00 inch es in 24 h oul's a r e not s ho wn . T a bulations of rains o f more than 8 hours are :-;how11 iu two or m ore lin es to11 neetecl by brackets. In such crises en eh amount in the second lin e in eludes the t ota l for the eight h o ur period in th e Ii nt. ~ above. Thl' hh.!h l•st amo unt in a on t:.>o r t wo-hour p e l'i od is not shown unl es s two inch es o J more fell in two co n sec utive hour s.

PAGE 26

TABLE 9.-RAINS OF Two INCHES OR MORE AT THREE STATIONS NEAR LAKE OKEECHOBEE. (I!:~~s) I Jan. I Feb. I Mar. I Apr. I May I June I July I Aug. I Sept . I Oct. l Nov. Dec. Everglades Experiment Stat io n, 1925 to 1938, Inclusive I I I I ' I I 2-3 2 3 I 5 3 9 i 3 5 I 5 2 2 I r I I 3 -4 I I 1 4 i 1 I 1 2 1 3 4-5 I I 2 I 3 I 5-6 I I I i 6-7 I I 1 I I I 8-12 I I i i 1 i 1 I I I I I I I I I U. S . Ca ne Br ee ding Station, Canal P o int, 1923 to 19 38, Inclusive I I I I ' I I I I 2-3 ; 3 2 1 7 2 3 6 5 1 3 2 1 I 3 -4 1 3 ' I I 1 I 4-5 I 1 2 1 \ 2 \ 2 5 6 I 1 1 1 I 6 -7 I I 1 I 7-8 I I I 21-22 I I I i i I I I 1 I i I ! I I Mo o re Haven, 1918 to 1938, Inclusive (see note) I I I I I 2-3 I 1 1 4 5 10 I 7 6 I 10 8 3 3-4 I 1 1 2 I 2 4 2 2 1 ~ 4-5 i 2 I 1 1 1 I I 5-6 I 1 -I 8-9 I l I i I I '! I I I I Not e.There was no record at Moore Ha ve n from Feb. to Sept. 1921, and from S e pt. to Nov. 1926.

PAGE 27

Water Control in the Soils of the Everglades 27 One of the heaviest 24-hour rainfalls ever recorded in Florida occurred at Canal Point in November, 1932. The record at the U. S. Cane Breeding Station showed 21.92 inches. Nearly all the rain fell between 11 :00 p.m. November 6, and 7 :00 a.m. November 7. During the preceding day 1.90 inches was re corded, making a total of 23.82 inches for 48 hours. Other rain gages within a few miles of this station showed amounts varying from 19.0 to 21.2 inches in 24 hours. The heaviest 24-hour rain fall at the Everglades Station was 10.90, during the same No vember storm. The maximum 24-hour rainfall recorded within the state, 23.22 inches, occurred at New Smyrna in October, 1924. Table 9 shows the number of rains of two inches or more which have occurred in 24 hours at the Everglades Station, at Moore Haven, and at Canal Point during the periods of record. The number of rains are shown according to size groups as indicated in the first column. The data show an average of about four rains of two inches or more per year at each station and approximately 60 percent of these rains have occurred dur ing the four-month period from June to September, when there is little or no farming. Rains of four inches or over have occurred eight times in 14 years at the Everglades Experiment Station; 13 times in 16 years at Canal Point; and seven times in 21 years at Moore Haven. EVAPORATION AND TRANSPIRATION To determine the evaporation and transpiration from sugar cane and grasses, records have been kept for the years 1934 to 1938, inclusive. For this purpose four large steel tanks were used. Each tank is four by 12 feet in area by four feet deep and is set in the ground to a depth of 3.5 feet. The bottoms of the tanks were first covered with a three-inch layer of crushed stone about one inch in size so as to allow the water table to more readily equalize when water is added or withdrawn. The excavated peat soil was replaced in layers to an elevation about six inches below the tops of the tanks. The water table in the tanks was kept at a near-constant elevation by adding or with drawing water as needed, using a two-inch bilge pump for this purpose. The water added or withdrawn was measured in small tanks of such size that an inch over the large tanks was equiva lent in volume to a foot in the smaller tanks. The rainfall was measured in a standard rain gage placed nearby. The wind

PAGE 28

28 Florida Agricultural Experiment Station movement, shown in total miles per month, was recorded on the top of a two-story building about 1,000 feet from the tanks. The crops planted in the tanks were surrounded by other plant ings on the outside to protect the tank growth from an excessive exposure to wind and sunlight and thus approximate fie'.d condi tions as closely as possible. The open pan evaporation data were obtained from a standard U. S. Weather Bureau open pan located near the steel tanks. Tables 10 to 14 show the evaporation and transpiration records for the years 1934 to 1938, inclusive. The cane record covers a period of five years. The total evaporation and transpiration for the four-month period from June to September was approximately 49 percent of the total for the five-year period and the total for the two-month period from July to August was 27 percent of the five-year total. The ratoon of cane cut in January does not reach much size till June and the period of heavy growth extends through September. During these summer months the days are long and the tem peratures high; hence the heavy evaporation. The average an nual loss from Tank 1, for the period of 1934 to 1937 inclusive, was 46.8 inches. The 1928 record is not included as the ground was kept heavily mulched during that year. In field practice the cane is usually burned over before harvest and after cutting the fields are fairly well covered with trash from cane tops. This covering is probably a little thicker than that on the tanks. The water table in the tanks averaged about 1.5 feet, while that in the cane fields probably averages about two feet. Hence the field evaporation would be a little less than the figures shown. It is estimated that the evaporation and transpiration over large cane areas is between 42 and 45 inche8 per year. During the years 1937 and 1938 evaporation records were kept for a tank covered with three or four inches of cane trash. The water table averaged approximately 1.4 feet. The evaporation for the first year was 12.2 inches and that for the second year was 9.1 inches. The record for 1937 shows that the evaporation from the mulched tank was about 30 inches less than that from a bare soil tank which was partially shaded by cane around the tank. During the year 1938 the cane tank was also covered with a similar mulch of cane trash in order to determine the approxi mate transpiration through the cane. The results indicated that 25.9 inches of the total loss from the cane tank was trans piration. The cane yield was 37.4 tons per acre. Calculations

PAGE 29

TABLE 10.-EVAPORATION AND TRANSPIRATION FROM TANK3 AND OPEN PAN FOR YEAR 1934, EVERGLADES EXPERlMENT STATION, BELLE GLADE, FLORIDA. Month Wind Motion Jan. 4,600 Feb. 5,070 Mai. 5,650 Apr. 4,950 May 4,100 June 3,860 July 3,330 Aug. 3,410 Sept. _ _ --------3,540 Oct . ... . . ------------I 3,980 Av era ge Evaporation and 0 -wJteJ 0 T~~re 1 I T~~r e 2 I __ F_e_e_t_ ~ _ _ I_n_c_h-es , Inch es I Transpiration Bare Soil I Tank 3 Inches \ Open Pan Inches Rainfall M ean Tempera ture Inches ~ ! ~ ~0 2.39 3.63 0.14 2 . 86 3.69 1.91 ; t 38 5.56 7.10 4.62 6.96 3.11 :rn7 G.4o 5.20 1 4.5!J 6.19 10.15 I -1.
PAGE 30

TABLE 11.-EVAP0RATION AND TRANSPIRATION FROM TANK, AND OPEN PAN FOR YEAR 1935, EVERGLADES EXPERIMENT STATION, BELLE GLADE, FLORIDA. I Wind Average Evaporation and Transpiration I Mean Month I Motion Depth to Cane I Cane I Bare Soil I Alfalfa I Open I Rainfall TemperaWater Tank 1 Tank 2 Tank 3 I Tank 4 I Pan ture Miles I Feet Inches inches Inches Inches I Inches Inches F. o I Jan. . .. .... ... 5,179 1.80 0.93 0.87 2.08 1.74 3.81 0.30 63.4 Feb. .......... 4,143 1.78 1.76 1.62 2.24 2.46 4.25 1.32 63.1 Mar. 5,087 1.79 1.98 1.64 2.94 2.23 6.52 0.41 68 . 8 Apr. 4,434 1.38 3.15 4.86 3.81 3.06 7.50 5.32 71.1 May 4,073 1.82 2.94 2.73 2.79 4.22 8.84 1.08 76.1 June .... . . .... 2,990 1.46 4.11 4.14 3 . 54 5 . 01 6.55 8.45 77.3 Ju'.y 3,851 1.67 5.83 6.26 4 . 16 6.70 7.38 6.37 79.3 Aug. ...... . ... 2,956 1.55 6.54 7.16 4.37 7.28 7.02 6.54 80.1 Sept. . .. . ... ... 4,111 1.28 5.64 5.28 5.55 3.69 5.54 10.88 79.1 Oct. 4,898 1.36 5.30 5.46 3.81 3.60 5.37 5.71 75.9 Nov. .......... 1 4,148 I 1.82 5.25 4.11 1.50 / 2.49 4.32 0.36 69.0 Dec. 4,820 I 1.65 3.08 2.42 2.42 I 2.64 3.50 2.07 56.4 I I I Year .. ....... . 1 50,690 1.61 46.51 46.55 39 . 21 45.12 70.60 48.81 71.6 I Note . -Can e in both tanks was the same type as in previous year. S ) i} was covered with dry cane leaves until Jan. 21, thus reducing evaporation for a period of three weeks. Cane growth was stopped by killing frost o Dec . 1 and crop was harves t ed on Jan. 14. 19 36 . Cane in Tank l was retarded by wireworms. The yield was 42.0 tons per acre . Tank 2 was re , >lanted on April 15. beca use of wir ew o r m damage . Tl:e cane yield was 28 . 6 tons per acre. Tank 3 contained bare soil partially shaded by cane around the outsi 'e. but the shade was not equ i val e nt to usu a l cane field conditions. Tank 4 had soil substantially bare prior to April 16 when alfalfa was planted. At first the alfalfa made good pro g re s s but the stand deteriorated during the summer, and only a scattered growth remained in the fall; he.u~e the drop in evaporation. VJ ..... A ..... .... C ;::s

PAGE 31

TABLE 1 2.-EVAPORATION AND TRANSPIRATION FROM TANK'3 AND OPEN PAN FOR YEAR 1936, EVERGLADES EXPERIMENT . STATION, BELLE GLADE, FLORIDA. Av. Depth to I i I Ev a poration and Transpiration I Mean Month Wind Water in Ft. I Ra infall I T e mp e raMotion Tank s I Tank I Cane ISawg ra ss j Bare S oil I Gra ss I Open I I ture 1. 3 & 4 2 Tank 1 I Tank 2 T an k 3 I T ank 4 Pan I I , I Inches Inches In c hes I Inch es Inches Inches I F. ' Miles I I I I Jan. --------i 4410 1.38 * 1.43 * I 1.20 I 2.67 4.18 1.91 65 . 1 I Feb .......... .. ... . [ 499 4 I 1.21 * 1.02 ,1, I 1.12 2.87 3.81 4.04 63.5 Mar . 5050 I 1.42 * 1.64 * I 2 . 0 8 4. 34 6.22 2.40 65 .5 Apr . ..... ... ... ... . . 4520 1.47 0.72 3.48 2.n I 3 .54 6 .80 7.68 1.96 70 . 6 May . ... . ..... .. .. . 4709 I 1.24 0 .75 5.55 3.22 I 4.43 5.24 7.40 6 . 39 73.8 June .. . ..... . . ... . 3526 I 1.00 0. 5 9 5.94 4 . 86 I 4 .5 6 I 4.86 5.94 18 . 61 77.0 July ...... ..... .... . 3943 1.47 1.00 6.45 5 .42 I 4 .!J 4 I 7.2 8 7.37 6.09 81.1 Aug. 3337 I 1.46 1.00 5.36 6.60 I 4.74 5.95 6.54 5.33 80 . 6 I I Sep t. 2707 1. 31 0.97 3.87 5.4.'l I 3.78 4.38 4.92 5.84 7 9 . 3 Oct. ......... ..... . . 3509 1.46 1.08 3.56 4.25 I 1. 8!) 3.44 5.15 1.65 78.1 Nov. -.. , 3755 1.14 0 .8G 2.76 4.86 I 2.76 2 .1 3 4 . 28 9.17 68.0 Dec. -------1 38 50 1.42 1 . 02 2.70 4.06 0 .93 I 1.95 3.13 1.18 67 . 0 I I I Year ..... ---I 48 ,310 1.33 43.76 51.!)l 66.62 64 .57 72 .5 Note.-Cane (F;H-1037) wa s cut Dec. 29, i ns. Yield of mill can e w ,s 28.4 ton s p er acre and 20;; lb s. of 96 su;mr per t o n. Sawgra ss was se t in Tank 2 o n Mar. 3. By May 1 o ld sawgras s h ad J ied down a nd n e w s pr o ut s a pp ea red. Stand did not reach fuJI size until Nov. Ther ea ft~r a l.!ood sta nd was maintained. So,! in T a nk 3 was partially shaded during y ea r by cane ar o und ta nk . Tank 4 was planted to Alfalf a on Jan. 2V . Stand died do wn by oumme r and w as m ost ly grass and weeds during last half of year . *No rec ord.

PAGE 32

TAB L E 1 3.-EVA P 0 R A T ION AND T RANSP IR ATION FROM T ANK S AND OPEN PAN FOR YEAR 1937, EVERGLADES EXPE RI MEN T STATION, BELLE GLADE, FLORIDA. Mont h I an. ... . . . .. .. . --eb. .... .... ar. .. .. . .... . I pr .. J F M A M J J A s 0 N D ... .. . .. . I 1 ay. ... . . . . . i une .... . .... ! 1 uly .. ..... . . .. . .• j u g. ept . . .. ...... ct. ov . -ec . i Wind Motion Mile s 4076 4283 4235 4 0 37 3275 2978 2914 2853 28 12 33 45 4418 4275 Y ea r ... 1 43,50 1 I I Av. Depth to i Water i n Ft. I T anks I T ank I Can e 1, 3 & 4 2 I Tank 1 ! I In c h es I 1.28 0.77 1. 73 i 1.47 i 1.05 2.46 ! ! 1.49 I 1.06 3.36 1.18 0 . 84 4.63 I 1.88 1.04 5.85 1.12 0 . 77 4.33 1.38 0.96 5.43 1.31 0.88 5. 24 1.26 0.95 4. 79 1.30 0.93 3.4 4 1.40 0.93 2.4 9 1.52 0.99 1.67 1.34 0.93 45 . 42 . --. . I Evaporation and T ra n s p irntion I Mean I Ra i n fall T emperaISawgrass \ Bare So il \ Mulch Soi l l Open ! t u re I Tank 2 Tank 3 T ank 4 I Pan ' , I I Inches I Inches I , In ches I I nches I I n ches F. , 5.61 ! 1.75 0.53 4 . 44 I 2.97 7 0 .8 I 4.93 2 . 91 0.66 I 3.86 ! 1.2 1 64.7 I i I 6.24 : us 0.71 I 5.30 5.87 66. 1 7 . 53 4.26 1.06 6.30 6 . 00 70.0 i 9.64 4.54 ' 1.0:'i i 7.77 3.38 74.0 . 7 . 05 4.53 1.1 8 6.70 7 . 74 78.3 fUJ 5 -5.0!l 2.05 I 6.66 I 7.65 79.7 8.80 4.99 1.48 6.02 I 7 . 89 80 . 6 8.93 4.38 1. 39 5.58 I 8.35 78 . 9 7.60 3 . 20 1.10 4.9 3 ' 1 4.92 73.8 4.14 1.44 0. 55 3 .76 I 2 .08 67 . 1 3 . 62 1. 41 0 .43 3 . 12 I 0.3 8 63.2 8 4.04 42.28 ! 12 . Hl 6 l.44 58.44 72 . 3 Not e.Cane (F'.ll-1037) was cut D ec. 17. Yield of cane was 20.0 tons pe,• ac r e and 219 l bs. of % 0 s u ;a r pe t t on. Stand was poor probably due to wir e worm::1. Sawg r a s~ fully grown an d s haded by cane around tank . Slan
PAGE 33

TABLE 14.-EVAPORATION AND TRANSPIRATION ~'ROM TANK S AND OPEN PAN VOR YEAR 1938. EVERGLADES EXPERIMENT STATION, BELLE GLADE, FLORIDA. Month J an. Feb. Mar. A ..... ... .... i Jlr . ..... . ... ...... l May ... 1 June .... .... ... .. 1 July ... ) Aug . . ) Sept. .. .. J g~~.... 1 Dec. .. .. 1 Wind Motion Miles 4140 4685 3833 4300 3224 2913 3 188 3062 2961 4220 3663 3554 i ---~ --Y ea r ,I . .... ... [ 43,743 I Av. Depth to Water in Ft. Evaporation and Transpiration ----Tanks Tank 1, 3 & 4 2 1.(iO 1.45 1.4:J 1..51 1.37 1. 3 !) 1.26 1.4 5 1.:36 1.4 : -l i _ ui . _ _ _ 1 0.78 0.90 1.02 1.04 0 .9 2 0.90 0.94 1.00 0.88 0.95 0.90 0.96 Cane Tank 1 Inches 0.56 0.62 o.n 1.2~! 2.33 3.9:l 5.70 6.00 5.46 3.45 2.67 2.29 1.43 _ . !_o_.9 _ 3 _ I 35.03_ l ' Sawgrnss Tank 2 i Inches .J.OJ 4.17 6.4!1 7. : 1:2 7.6!! 7.fiH (i.72 7.05 5. 9!1 5.0!1 8.48 2.25 __ _ i G7.85 Grass Tank 3 Inches 2.87 . 1,!J:-l 6 .27 G.B8 7 . 26 =>.G:l !'; .8 0 -I.G5 -1.84 : J.57 2.fi!J Rainfall I Mulch Soil / Open Tank 4 Pan I Inches I Inches Inches 0.56 0.5!! 0.43 0.4G 0.76 l.ll 1.6 5 0 .5 !1 1.08 0.78 0.81 I 0.28 I _ __ i _ :J.G!I 0.4G 4.22 1.14 5.85 1.87 6.78 0.32 6.66 4.52 G.G0 5.:14 6.64 8 .85 6.75 2 . 65 5.!12 i 10.09 5.:l4 1 2.78 4.08 ) 2.GG ;LJ(j I 0.21 __ L _._ 9.10 G5.7\J 40.9H J Mean Tempera ture F. o 62.5 G5.4 G8.9 69.8 75.8 77.6 79.0 79 .8 78.6 72.5 71.2 6:3.7 72.1 Not c . Cane \F31-436) was plant e d la s t week of Dec., 1937, and cut Jan. 3 . 193n. Yield was 37.4 tons per acre . Both Cane Tank l anJ Mulch Tank .1 were covere:l with a heavy lay er of ca ne trash during the year . The difference between the total evaporations of the 2 tanks or 25.93 inch es i s rou ;.! hly the transpiration lo s :1 throu .::r h t h e cane. This amounted to '1 8 .4 pounds of water per pound of mill canep and 763 pounds of water p e r p o und o f !)6 s ugar. Th e s aw g rass in Tank 2 was surrounded by cane for a windbreak. The stand of sawgrass was below normal I.luring t he la st haJf of year. Tank :S was planted to Bahia grass in January. The grass was not cut during the year. "'No r ec ord .

PAGE 34

34 Florida Agricultural Experiment Station by Mr. F. D. Stevens, sugarcane agronomist, Everglades Station, showed that the transpiration amounted to 78.4 pounds of water per pound of mill cane, and 763 pounds of water per pound of 96 sugar. The four-year evaporation record from the uncropped and un mulched tank showed an average loss of 40 inches per year. The difference between the several years is doubtless due, in part, to variation in the amount of shading and probably also to varia tion in frequency of rainfall. When the surface soil is kept wet by frequent rains evaporation increases. On January 29 , 1936, one of the tanks was planted to alfalfa but the stand died down by summer and was mainly grass and weeds during the last half of the year. Evaporation and trans piration for 11 months exclusive of January totaled 49:2 inches. On January 3, 1938, a tank was planted to Bahia grass. The grass grew well and was not cut during the year. Cane was planted around the tank as a windbreak. The water table aver aged 1.4 feet. Evaporation and transpiration for 11 months, exc!usive of January, were 54.0 inches. The estimated total for a full year was 57 inches. It is evident that the losses from grass land are very high. To s ecure data with which to estimate the evaporation from the sawgrass land of the Everglades, the sawgrass plants from an area of 4x12 feet were transplanted in a tank of the same area in March, 1936. By May 1 the old sawgrass had died down and new sprouts appeared. These did not reach full size until November. Through the year 1937 the stand was equal to that on the land from which the plants were taken. Cane was planted around the sawgrass tank to serve as a windbreak. The water table averaged nearly a foot in depth. Evaporation and trans piration for the year 1937 amounted to 84 inches. During the last half of the year 1938 the sawgra s s deteriorated to a considerable extent, but was probably somewhat better than the average stand on the virgin areas of the Everg : ades. Evap oration and transpiration for the year amounted to almost 68 inches. There are very few data on average depth of water table in the sawgrass area of the Everglades. The water table may vary from surface to a depth of four feet or more. It probably aver ages about two feet. Annual evaporation from the Everglades would be somewhat less than that from the tank, due to the deeper water table and also a little better protection from wind.

PAGE 35

Water Cont?ol in the Soils of the Everglades 35 After making some allowance for these differences it is estimated that the mean annual evaporation from the sawgrass lands aver ages about 60 inches. As this is substantially more than the average rainfall of approximately 53 inches, the results indicate that run-off and seepage from outside areas are a considerable factor in maintaining the water table beneath the peat lands of the Everglades. Evaporation records from a standard Weather Bureau open pan have been kept by the Everglades Station since 1924. The records for the years 1934 to 1938 show a five-year average loss of 66.54 inches. This evaporation is considerably higher than that from a large open body of water such as a lake. Experi ments, in the arid West, conducted by the Irrigation Division of the Soil Conservation Service, USDA, 6 indicated that the evaporation from large bodies of open water is approximately 70 percent of that from a standard Weather Bureau open pan. If this ratio also holds for the humid region, the mean annual evaporation from a large body of water such as Lake Okeechobee would approximate 47 inches. TEMPERATURE The mean annual temperature at the Everglades Station for the five-year period of 1934 to 1938 was 72.1 F. August was the warmest month with an average of 80.2 and December was the co'dest with an average of 62.8 for the five-year period. The Everglades Station has kept a record of temperatures since July, 1924. The maximum of 100 was reached three times in July, 1931. The minimum recorded at a height of four feet above the ground was 25 on January 15, 1926, and again on December 13, 1934. The record shows that temperatures of 32 or less were experienced 12 times in December, 11 times in Jan uary, three times in February and six times in March, during a period of 14 years. The Everglades Station has kept a record of minimum tem peratures from a point near the Hillsboro locks west of Belle Glade to Twenty Mile Bend on the West Palm Beach Canal. The thermometers are located near State Highway 25 and are set in boxes about four feet above the ground. Table 15 shows the readings at the several stations for periods when the minimum at the Experiment Station was 38 or less. Readings at the Rohwer, Carl. Evaporat i on from fre e water surfaces. U. S. Dept. Agr. Tech. Bui. 271. 1931.

PAGE 36

36 Florida Agricultural Experiment Station Experiment Station, 4.3 miles below the Hillsboro lock, are taken each day, but those at the other stations were usually read once a week during the cold portion of the year. The readings are TABLE 15.-MINIMUM TEMPERATURES ALONG HIGHWAY No . 25 FOR PERIODS WHEN MINIMUM WAS 38 F. OR LESS AT THE EVERGLADES EXPERIMENT STATION FROM DECEMBER, 1929, TO MARCH, 1938. Date Distance from Hillsboro Lock No. 1 in Miles .--'--'o_ .2 _ _,_ 1 _ 1 _ .3_.....,l '-2 _ . ..:... 6 _ '---4 _ . -=3 _ ,___8_.4_*_* --'--13.:...._5* _* _..;.._2_1.:..:..5 _* * I I 12/26 /29 I 38 .0 I 34. 0 32 .5 33.5 27.0 1 /3 1 /30 38.0-*) 38 .03 5.036.03 / 5/30 1 1 30.0 28.0 30.0 30.0 26.5 11 /26/30 ......... . 37.0 36. 0 36 .0 35.0 34.5 12110 ;3 0 ......... ! 31.0 I 28.5 29.o 28.5 23 . 0 12115 13 0 .. ..... .. 1 38.5I 34 .034. 035.512 / 24 /3 0 .1 41.039 .040.034.012 / 28 /3 0 ......... , 38 .5 I 35 .0 35.o 35.o 1/7 /31 .. ............ ! 35 .0 3 1.5 30.0 29.0 1/15 /31 ............ ! 38.5I 38. o37.536.51122 ;3 1 ............ [ 39.o 38.o 3 7 . o 32.o 3/5 / 31 . i 34.5 33 .0 33. 0 32.0 3 / 12 /3 1 .. .. ...... . / 45.o 44. o 41.0 30. 0 4 / 8 / 31 . ' 39.0 3 5.5 32 .5 33.0 10110 1 32 ...... . [ 43.o 37.0 37.5 37.o 3/14 /32 ............ [ 35.o 3 0.o 30.o 32.0 1/29/3 3 . . ......... 1 32 .5 28.5 30 .0 34.0 2 / 6 /3 3 .. , 36.0 31.0 34 .0 35.0 3 / 4 / 33 . . ........ . 1 34 .0 29.0 31. 5 34.0 1/11 /3 4 .. . ..... . 1 45.0 37.0 35.5 37.0 1/31 /34 ............ [ 42.o 38.o 35. o 38 .o 2131 3 4 ..... I 41.0 3 4.5 37.o 36.o :V12 / 34 ... .... . . ... 1 3 2.034. 0 34.512 / 1 3 / 34 . ... 1 26.5 27.0 23.0 25.0 12 / 14 /3 4 I 40.0 35 .0 36 .0 37.0 1/24 /35 ...... . [ 41.0 39.5 38. 0 36.0 2/5/35 .. . 32.0 3 0.5 30.0 31.0 2 / 21/ 3 5 38.5 37 .0 35. 0 38.0 2 / 28 / 35 .. 1 39 .539 .037 .012 / 1 / 35 .... . 3 0.0 30.0 31.5 34.0 12/19 /35 .. 35.5 3 2.0 32.0 34.0 12 / 21 /35 3 0.0 30.0 3 0.0 30.0 2/1 / 36 . . ............ 38.0 37.5 36.0 36.0 2 / 11 /3 6 36.0 36. 0 35 .0 37.0 3/19 /3 6 ............ 1 37.0I 36 .oI 36.oI 36.03/22 /36 ............ 1 34.0 I 33.5 34.o 35.o 11/28 /3 6 41.0 34.02 / 6 /3 7 ' 33.033 . 537.011 / 21 / 37 .. 1 40.040.036.036 .012 /7 /3 7 32.032. 029.031.01/28 /38 30.03 0.028.032.02/26 /38 . . ......... 1 39. onoI 38.o32.0 23.5 35.032.0 27.0 34.0 28.0 37.0 27.0 28.5 28.0 24.5 34.5 37.0 26.0 33.018.0 30.0 32.0 21.5 30.0 31.026.0 27.0 25.0 33.0 33.0 33.029.0 27.034.028.024.534.028.0 26.0 32.0 23.0 30.032.032.0 22.5 34.0 29.5 35.0 31.0 32.0 28.0 32.0 30.0 29.0 33.0 31.0 27.0 30.013.0 29.0 30.0 27.0 30.0 25.027.0 27.5 24.5 30.5 28.0 36.035.0 36.030.027.0 31.0 21.0 33.0 23.0 28.5 31.0 30.0 20.5 35.031.0 27.5 35.0 28.0 30.0 25.0 28.0 31.0 27.0 28.0 31.0 26.5 29.0 13.0 25.0 28.0 28.0 27.0 26.0 26.5 28.0 24.5 31.0 33.0 37.0 36.030.026.0 l i i i I _ _ ___, Average ........ / 36.5 / 33 .7 I 33 . 3 I 33.6 __I . 28.8 I 28.8 I 27.7 .*Readings marked (-) are not included in avera!!es. C"a tions at Mil ei:; 8.4; 1 !{.5; a n
PAGE 37

Water Control in th e Soil:; of the Everglades 37 the minimums for the period covered and when the minimum for the period was 38 or les s at the Experiment Station the corresponding readings at the several s tations are shown as of the same date. For this reason all readings of 38 c or le ss at the Experiment Station are not shown, for if the minimum were 38 for one day of the period and 35 for another day only the lowest reading would be shown. The table shows the change in minimum temperatmes with distance from Lake Okeechobe e. The stations at 0.2, 1.3, 2.6 , and 4.3, miles from the lock are on cultivated ground while those at 8.4, 14.0, and 21.5 miles from the lock are on virgin land. The lo c k is 1.3 miles from th e new lake levee. The data indicate that low temperatures at the lock average nearly 3 warmer than tho s e at the Experiment Station (4.3 mi.) and nearly 9 warmer than those at Twenty Mile Bend (21.5 miles). There is reason to believe that these low temperatures in the virgin land would be 3 or 4 higher if the land were in cultivation. The very loo se top soil and mulch of leaves and trash on the virgin land acts as an insulating cover which retards the flow of heat from the wet soil beneath to the ail' above. The Shawano Plantation i s locat e d on the Hill s boro Canal about 11 miles southeast of the Everglades Experiment Station. A record of temperatures on the cultivated areas in that loca tion is available since January I, 1929. A comparison of the minimum readings of 38 or less at the Experiment Station with those at Shawano shows thos e of the latter station to aver age I.I O lower than at the Experiment Station. However, the difference is somewhat greater when the comparison is confin e d to very low temperatures. From January, 1929, to March, 1938, a tabulation of temperatures, when the minimum was 32 or less at either of these s tations, showed an average difference of 2 , while the minimum reading s on cultivated land near Glade view (13.5 miles) showed a difference of 4.8 . As the station near Gladeview is about the same distance from Lake Okeechobee as that at Shawano, the comparison indicates that temperatures of 38 or less will average from 3 to 4 higher after the virgin land is p"laced in cultivation. On March 14, 1932, a minimum temperature of 9 was re corded on a thermograph located one foot above ground on virgin sawgrass land at the Shawano plantation. The water table was very low in the soil at that time and the Glades very dry and

PAGE 38

38 Florida Agricultural Experiment Station covered with a deep mantle of dead weeds and sawgrass from earlier frosts. On December 13, 1934, two readings of 13 were recorded on virgin land (see Table 15). One was 13.5 and the other 21.5 miles east of the Hillsboro locks along State Highway 25. A minimum thermometer set by the Everglades Station 15 miles below South Bay and 600 feet west of the North New River Canal on virgin land recorded a low of 14.0 on or about March 5, 1930. These records indicate that very low temperatures occasionally occur in the virgin areas east and south of Lake Okeechobee. It is probable that higher minimum temperatures would result if the water tables in the outer areas could be held near or above the surface. WATER CONTROL BY PUMPING The early drainage of the peat lands around Lake Okeechobee depended on gravity systems discharging into the large outlet canals, which were never entirely completed. Due to the flat topography the ditch gradients are only a few inches per mile and hence the water movement is very slow. The subsidence following original drainage further reduced the effectiveness of the gravity systems. To improve their drainage nearly all the sub-districts in the northern Everglades have installed large pumps, and many farmers also have installed private pumps to increase the effectiveness of their water control. The first large pumping plants were built in 1925. As most of the pumps are reversible, water as needed may be pumped into the areas served and thus control the water levels during dry periods. The majority of the large plants are located near Lake Okeechobee and discharge into the lake; however, a few are located farther back on the large canals and the water from these may run either into the lake or down the canals, depending on the relative lake and canal stages. The amount of pumping varies widely from year to year, depending largely on the amount of rainfall. There is little pumping from November 1 to June 1, the dry portion of the year. Nearly all the large plants use the screw type pumps with a capacity of from 30,000 to 60,000 gallons per minute, but in recent years a few large vertical turbine pumps of 30,000 to 40,000-gallon capacity have been installed. The large screw pumps are driven by heavy duty diesel engines of from 80 to

PAGE 39

Water Control in the Soils of the Everglades 39 180 horsepower and one large vertical turbine pump uses a 125 horsepower electric motor. This particular pump is operated under an off-peak contract and the cost of power has averaged approximtaely 1.8 cents per k.w.h. The drainage districts of the northern Everglades have in stalled pumping plants with a total rated horsepower of approx imately 5,500 and a total capacity of approximately 4,200 second feet. The average static lift is probably close to four feet and the maximum lift has seldom reached eight feet. The discharge capacity of most of the large pumping plants is approximately one inch in 24 hours over the area served, but a few have capaci ties of 1.5 inches. In addition to the large plants there are a number of small plants serving areas of 80 to 640 acres. These are usually privately owned. Many of them are located within the areas served by the district pumps and provide additional facilities for controlling the water table on individual farms. The capacities of these smaller pumps usually range from 1.5 to 3 inches. Approximately 100,000 acres in the northern Everglades are served by pumps and about 85 percent of this acreage is in agricultural use. Approximately 60 percent of the rainfall near Lake Okee chobee occurs during the four-month period of June to Septem ber, and by far the greater part of the pumping is done during these months. During the late winter and spring months a small amount of water is pumped into the districts to raise the water table. This will probably not average over six inches and will seldom exceed 12 inches in the driest years. A comparison of the amount pumped with the e s timated difference between rain fall and evaporation indicates that seepage accounts for a large portion of the water pumped from a drainage area. DESCRIPTION OF PUMPING PLANTS During the six-year period of 1933 to 1938, inclusive, pumping records have been kept on four large plants near Canal Point and on one small plant at the Everglades Station. The locations of these plants are shown in Figure 1. The four large plants located in the Pelican Lake and Pahokee drainage districts are fairly typical of the larger plants around Lake Okeechobee. They have a discharge capacity of one inch in 24 hours and may be reversed to supply irrigation water when needed. The cultivated acreage is largely planted to sugarcane, but a substantial amount is used for truck crops. All four plants pump directly into the

PAGE 40

40 Florida Agricultural Expe1 iment Station West Palm Beach Canal and the amount of pumping is consider ably affected by the canal stage. The small plant at the Ever glades Station near BeIIe Glade discharges directly into the Hills boro Canal. This area served is planted to experimental crops of cane, truck and grasses. A larger amount of pumping is done through the summer than is usual on other land. Figure 6 shows a typical pumping plant of the northern Everglades. Fig. 6 . -A typical large pumping plant of the northern Everglade s. Such plants contain from one to three pumps of approximately 56,000 gallons capacity each. Pelican Lake Unit No. 1.-The two engines are each 80 horse power, vertical, two-cylinder, type Y, diesels, made by Fairbanks Morse and Company, and are directly connected to the pumps. The full speed is 300 revolutions per minute, but this can be varied by special adjustments. The two pumps are each 42-inch Wood-screw type, with a rated capacity of 30,000 gallons per minute. The pump house is made of corrugated metal on timber framework and is set on a concrete foundation. The total cost of the plant was $55,000. Pumping operations were started in 1925. Fuel oil consumption during the six-year period has averaged 1.14 gallons per acre-foot pumped, and 5.2 gallons per pump-hour of operation. The static lift has averaged 3.5 feet and the maxi mum lift was 7.1 feet. The plant-days of operation during a year has averaged 68.3. As one or more pumps in a given plant

PAGE 41

' !3 Water Control in the Soils of the Everglades 41 may be operated during the day, a plant-day is determined by adding together the total days of operation of each pump during the year and dividing the result by the number of pumps. Pelican Lake Unit No. 2.-This plant is similar to Pelican Lake Unit No. 1. The total cost of the plant was $51,000. Pumping operations were started in July, 1929. Fuel oil consumption during the six-year period has averaged 1.05 gallons per acre-foot pumped and 5.2 gallons per pump hour of operation. The static lift has averaged 3.9 feet and the maximum lift was 7.5 feet. The plant-days of operation during a year has averaged 44.2. Figure 7 shows the record of pump operations at the two Pelican Lake plants for the year 1934. Similar charts have been prepared for the other five years of record. Copies of these -j_, --------\----, --4-_t T ro,/ 9.71 1 " Fig. 7.-Record of pumping plant operation at Pelican Lake Drainage District, Florida, 1934. Total water pumped for drainage: Unit No. 1, 23,764.2 acre-feet (7.03 feet on 3,379 acres); Unit No. 2, 14,287.2 acre-feet (5.01 feet on 2,853 acres). Total rainfall (both units), 69.78 inches or 5.82 feet. Total fuel oil used: Unit No. 1, 26,300 gallons; Unit No. 2, 15,985 gallons. Average lift of pumps: Unit No. 1, 3.3 feet; Unit No. 2, 4.3 feet.

PAGE 42

42 Florida Agricultural Experiment Station may be obtained from the Soil Conservation Service, U. S. Dept. of Agriculture, Washington, D. C. Total amount of pumping, depth over the drainage area, rainfall, fuel oil used, and average lifts are shown for each plant. During the year 1934 Unit No. 1 pumped approximately seven feet from the drainage area, and Unit No. 2 pumped five feet. This difference is mainly due to the heavy seepage into the area of Unit No. 1 from undrained lands to the east. There is a large area of virgin land between the St. Lucie and West Palm Beach canals, much of which drains to the south. A high water table in lands outside of a pumped area materially increases the amount of pumping. A high stage in the West Palm Beach Canal also increased the pumping in each of these units, due likewise to seepage which reaches the pumped area through the porous limestone and sand beneath the peat. This seepage probably has little effect on the maxi mum rate of pumping, but prolongs the pumping period. The rainfall at Azucar, located between the two Pelican Lake units, will probably differ little from the average over the two drainage areas. For the years 1933 to 1938, inclusive, the an nual amounts were 61.1, 69.8, 52.5, 57.8, 55.7 and 39.3 inches, respectively. The average was 56.0 inches. If the rainfall, evaporation and depth pumped for a given area are known, an approximate estimate may be made of the seepage during a year. Azucar is located near the center of Unit 2 of the Pelican Lake District and all land is within two miles of the rain gage. Nearly all the land is in sugarcane. Records at the Everg'.ades Station indicate that the annual evap oration from such an area approximates 3.5 feet. The rainfall for 1936 was 4 . 82 feet, which is close to normal, and the depth pumped was 4.09 feet. These data indicate that the seepage inflow was equivalent to a depth of 2.77 feet. The average annual seepage depth for the six-year period was 2.5 feet. A large area under similar conditions would show a smaller depth of seepage. East Pahokee Unit No. 1.-The two engines are each 180 horsepower, vertical, three-cylinder, type Y, diesels, made by Fairbanks-Morse and Company, and are directly connected to the pumps. The full speed is 257 revolutions per minute and this can be readily reduced by a speed control mechanism on each engine, so that a fairly constant canal stage can be maintained at the pump intake. The two pumps are each a 54-inch Wood screw type with a rated capacity of 60,000 gallons per minute.

PAGE 43

Water Control in the Soils of the Everglades 43 The pump house is made of corrugated metal on steel frame work, and is set on a concrete foundation. The total cost of the plant was $75,000. Pumping operations were started in No vember, 1929. Fuel oil consumption during the six-year period has averaged 0.96 gallons per acre-foot pumped, and 6.8 gallons per pump-hour of operation. The static lift averaged 4.4 feet and the maximum lift was 7.5 feet. The average lift for the year 1938 was 2.9 feet. This low lift was due to the fact that the West Palm Beach Canal was at a very low stage during the year and a!so because there was considerable pumping for irrigation in December when there was little or no lift. Some water was siphoned into the district through the pumps with the engines disconnected. The plant days of operation during the six-year period has aver aged 39.5. East Pahokee Unit No. 2.-The equipment of this plant is similar to that of East Pahokee Unit No. 1, except that there are three engines and pumps instead of two. The total cost of the plant was S105,000. Pump operations were started in January, 1930. Fuel oil consumption during the six-year period averaged 0.91 gallons per acre-foot pumped and 7.7 gallons per pump-hour of operations. The static lift averaged 4.1 and the maximum lift was 7.6 feet. The average lift for the year 1938 was 2.3 feet. This low lift was due to the low stage of the West Palm Beach Canal and also to the large amount of pumping for irrigation in April, May and December, when the lift was very low. The amount pumped for drainage in 1938 was 7,757 acre-feet and that pumped for irrigation was 11,039 acre-feet. The plant-days of operation during the six-year period averaged 40.0. Figure 8 shows the record of pump operations at the two East Pahokee plants for the year 1934. Similar charts have been prepared for the other five years of record. Copies of these may be obtained from the Soil Conservation Service, Washington, D. C. The amount pumped, depth over the drainage area, rain fall, fuel oil used, and average lift are shown for each plant. The records indicate that the stage in the West Palm Beach Canal has a substantial effect on the amount of pumping. This is particular : y evident when a comparison is made of the pump ing in August and October, 1935. The drainage areas of these two units are not completely separated, as a ditch at the west end of the district may carry

PAGE 44

, , , oo " 44 Florida Agricultural Experiment Station water to either unit. The six-year record for Unit 1 shows an average annual depth pumped for drainage of 2.26 feet and for irrigation of 0.004 feet. The record for Unit 2 shows 2.25 feet pumped for drainage and 0.30 feet for irrigation. The two units combined show 2.26 feet pumped for drainage and 0.20 feet for irrigation. In 1938, the driest year of record, Unit 2 pumped 0.82 feet for drainage and 1.16 feet for irrigation. The rainfall near the center of Unit 1 for the years 1933 to 1938, inclusive, was 64.57, 66.20, 49.36, 57.45, 53.84 and 33.72 inches, respec tively. The average was 54.19 inches. There was no rain gage in Unit 2, but the rainfall will probably differ little from the above. A comparison of the depth pumped by Pelican Lake Unit No. 1 --. ' ' 7. --_ .. --,-' ' . . , _____ __ 1 ---i 40 0 . . --t JO O ---~ ] 20 0 ---i .. ! 1 00 ---1 o . A. c rete e 1 c, 700 1 1:, 6 00 ---------J 4 0 0 . ---1 .
PAGE 45

Water Control in the Soils of the Everglades 45 with that of East Pahokee Unit No. 1 shows that the six-year average for the former plant was almost twice that of the latter plant. The effect of a high water table outside of a pumped area is here clearly shown. Pelican Lake Unit No. 1 abuts on virgin land to the east in which the water table is usually high due to seepage from higher lands. On the west it abuts on the sandy ridge along Lake Okeechobee whose average stage is as high as the lands in the pumped area. The East Pahokee Unit No. 1 adjoins pumped lands to the north, south and west. Both areas have about the same frontage on the West Palm Beach Canal. Everglades Experiment Station Plant.-The electric motor is a four-speed Westinghouse, type C. S. induction model. It is rated from 4.2 to 30 horsepo,ver, depending on the speed used, and is connected to the pump by a set of short V-belts. The four speeds are 445, 590, 890 and 1,180 revolutions per minute. However, nearly all the operation has been at the third speed of 890 revolutions per minute. A small amount of pumping has been clone with an oil engine, but the energy so used has been estimated in equivalent kilowatt hours and added to the totals shown for the electric motor. The pump is a 24-inch vertical turbine rated at 10,000 gallons per minute at high speed, and is so built that water can be pumped either in or out of the area, served by the simple opera tion of four vertical slides. It was made by the Couch Manu facturing Company and has four speeds of 217, 292, 442 and 574 revolutions per minute. The pump is started and stopped by an automatic float in the intake ditch, and requires little attention during operation. The pump house is made of corrugated metal on steel framework and is set on a concrete foundation. The total cost of the plant was approximately $3,400. It began operating in July, 1931. The electric power used is three-phase, 60-cycle, 220-volt cur rent. The cost of power up to July 1, 1936, was based on a charge of $4.00 per "contract" horsepower for the first 25 "contract" units per month for four months in each yearly period; $3.00 per horsepower for all additional "contract" horse power per month for four months in each year; and 3 cents per kilowatt-hour for all energy used per month. Since July 1, 1936, the plant was operated under a new contract, but the cost of power was reduced only a very small amount, although the basis of calculating the cost was changed.

PAGE 46

,so 46 Florida Agricultural Experiment Station The record covers a six-year period. During the first three years the area drained was 162 acres, but after that period an additional 40 acres was added to the farm. This new land may drain either to the South Florida Conservancy District pump or to the Experiment Station pump. It is estimated that approxi mately 180 acres are now served by the Experiment Station pump and the cost estimates for the last three years are based on that area. The annual cost of electric power during the six-year period has averaged $3.90 per acre served and 6.1 cents per k.w.h. used. The average period of operation has been 49 days per year. The annual rainfall for the six-year period varied from 65.3 to 41.0 inches and averaged 56.7 inches. The static lift has averaged 2.1 feet and the maximum lift was 4.2 feet. The record Fe b . March Dec. '!!24 0 --\--200 , -+--L -< l , 1:i o _. I I ___ i L. -H ,1 L I 1 1 .2 kw.•lir. 87.4 Kw.hr I -~ '. -_L_ 4 0,?.4kw .h r . I -_J iE -_ __j_ --1-0 402okw h.r JO l " --r-I _ _ 1 __ _ ! : i ""J:; l t,.," .. .. ; r ~ __ _______ _ , ---l-1 ---__, --_ ----__I Fig. 9.-Record of pump operation at Everglades Experiment Station, Florida, 1934. Total water pumped for drainage, 1,411.1 acre-feet (8.71 feet on 162 acres). Total water pumped for irrigation, 87.7 acre-feet (0.54 feet on 162 acres). Total time of pumping, 1,338 hours (55.8 days). Total e nergy used, 12,665 k .w .h . Total cost of electric power, $780. Average lift of pump, 2.32 feet.

PAGE 47

Water Control in the Soils of the Everglades 47 for the six years shows an average annual depth of 6.9 feet pumped out for drainage and 0.65 feet pumped in for irrigation. Figure 9 shows the record of pump operation at the Everglades Station for the year 1934. Similar charts have been prepared for the other years. Copies of these may be obtained from the Soil Conservation Service, Washington, D. C. The amount pumped, depth over the drainage area, kilowatt hours used, rain fall, and stages of the Hillsboro Canal are shown for each year. The charts show that the amount of pumping is increased when the Hillsboro Canal is at a high stage. During May, 1936, with a rainfall of 6.4 inches and an average canal stage of 12.9 feet, only 12 acre-feet were pumped for drainage while in July with a rainfall of 6.1 inches and a canal stage 3.8 feet higher, 407 acre-feet were pumped. This increase indicates the effect of a high water table outside a cultivated area on the amount of pumping. This, however, is an extreme case, as the variation in outside water table is seldom so wide. The Experiment Sta tion area has a frontage of over a mile on the Hillsboro Canal and due to the use of the land for experimental purposes more pumping is done in the summer than is the case with ordinary farm land. These conditions account for the large annual amount of pumping. A small quantity of water is run into and out of the area by gravity, but it is estimated that the quantities will about balance. From evaporation experiments with sugarcane, grass, bare soil, and open water it is estimated that the annual evaporation from the Experiment Station farm will approximate 3.5 feet. This figure, used with the amount pumped and the rainfall, indicates a seepage inflow varying from two to seven feet per year and averaging five feet. As previously stated, the seepage will depend on the water table in surrounding lands and on the stage of the Hillsboro Canal. FIXED AND OPERATING COSTS OF PUMPING The installation costs and fixed charges for each pumping plant are shown in Table 16. The term "fixed charges" as used in this report includes the annual interest on the capital invested and the annual depreciation charge. The interest on invested capital is figured at 6 percent. The depreciation charge has been computed by the sinking fund method and the annual charge is such an amount that, invested at 4 percent compound interest, the sum of the payments and the interest will equal the cost of the building and equipment at the end of their estimated life.

PAGE 48

48 Flo rida Agric u ltural Experiment Station TABLE 16 . -FIXED CHARGES OF PUMPING PLANTS. I C I Intere st Total ost Depreat 6 Fixed ciation Perc e nt Charge s Plant I Engine s I I Building and Total Pump s ,--------p p $1,847 $3,300 $5,147 1 , 713 3, 060 4,773 I I I elican Lake I I I Unit No. 1 ) $2 4,250 I $3 0,1so l $55,ooo I I ! e li ca n Lak e I U nit No. 2 I 20,250 i 3 0,750 51,000 E E E 2,519 4,500 7 , 019 3,526 6,300 9,826 I I ast Pah o k ee : I Unit No . 1 I 32, 000 i 43 ,000 75,000 a s t Pahoke e I I Unit No. 2 I 40,000 65 ,000 105,000 I verglades I I 114 204 3 18 Experiment I I Station I 1,900 l 1.500 3,400 -As both the building and equipment in the plants studied are of a very durable type, the life of the entire plant has been esti mated at 20 years. The Wood-screw type of pumps have all moving parts above water and the heavy duty diesel engines are of a type that has been in use for 20 years in other fields. The foundations and floors of pump hou ses are concrete and the build ings are covered with corrugated s heet metal and all but one has s teel framework. The costs of fuel oil or electricity, lubricating oil and labor are shown in Tables 17a, 17b and 17c. The unit costs per acre served and per acre-foot pumped are also shown. The period of operation i s expressed in plant-days. As the oil engine plants h a ve two or more pumps and all or part of the units may be in operation at a particular time, the number of days on which some pumping was done was greater than the p~ant-days shown . The plant-days were determined by reducing the total pump-hours to 24-hour days and dividing the result by the number of pumps. The Wood-screw pumps were rated with a Pitot tube and cur rent meter. A record of the lifts and speeds was kept. The Experiment Station pump was rated with a current meter but during the last two years a submerged orifice has been used and the discharge computed from a continuous record of the head on the orifice. The cost of fuel oil delivered at the plants has ranged from 6.5 to 7.0 cents per gallon. The cost of lubricating oil and gasoline includes the gasoline used in the lighting plant, in the compressor engine and for the truck used in supervising the

PAGE 49

TABLE 17A.-COSTS OF FUEL OIL, LUBRICATING OrL. AND LABOR AT PUMPING PLANTS. ... I I I I / Year Size I Period of I Costs for Year Plant of Area I OperaI Water I Per I Per 1, Engine Served tion Pumped I Fuel Oil I Lub. Oil I Labor Total Acre Acre-Foot I I I and Gas Served Pumped :s:: I I H. P. Acres I Plant I Acre-Feet I Dollars I Dollars I Dollars I Dollars Dollars I Dollars .:i Days I I I NPelican Lake I l\J38 ](j() :3,:mi 82.8 rn,181 1,:l84 2H8 1,510 I 3,192 0.94 0.17 : c-:i Unit No. 1 I 1934 l(j() :i,:n9 103.4 ' 23,764 1.710 ! :no 1,910 3,930 1.16 0.17 C ;:l N1935 l(i() :•;,:-;7u 48.6 11,105 7fi4 175 1,250 2,189 0.65 0.20 -a: C ,,.... 1936 ](i() :3,:37D 62.8 14,174 1,08!1 220 1,535 2,844 0.84 0.20 "" ! ;:l N-1937 lH0 :~,::37!) 87.6 16,024 l ,.!8!i 2!i5 1,60:l 3,343 0.!HJ 0.21 ;::,-, (,:, rn:38 l(iO :i,:ml 24.4 4,!J04 :3!)8 1:l2 788 1,318 0.3!) 0.27 VJ 0 A vel'ag-e l(iO :i,:mi 68.3 14,85\J 1.nrn 2:i2 1,4:33 2,803 0.83 0.19 0 -----~~ ' ....... I, I ,,.,_ Peliean Lake 1933 1(,0 2,85.'1 41.5 !),858 718 15!) l ,062 i Ul:l!J 0.68 0.20 (,:, i t,j Unit No. 2 rn:34 l(i() ' 2,85:3 61.5 14,287 1,0::, 2:lfi 1,315 2,587 0.!11 0.18 "' "' 19% l r;o ' 2,85:3 30.G 7,488 4!12 l l'i 1,14:3 1,752 0.(il 0.2H 4 (Q 1936 ](i() 2,853 47.8 11,667 784 172 1,2!15 2,251 0.7!) 0.19 Ra ,:,:, I 1937 J(i() 2,853 65.6 15,08!1 1,124 205 1,:lrn 2,642 '.r. 0.D:l 0.18 1938 160 2,85:, 18.1 4,2:l2 274 120 ti78 1,072 o.:38 0.25 Average l(iO i' .. 2,853 44.2 10,4:37 7:rn HiH 1, l:l4 2,041 0.72 0.20 ~1 .... I """ ------~-I

PAGE 50

Plant East Pahokee Unit No. 1 Average East Pahokee Unit No. 2 Average TABLE 17B.-COSTS OF FUEL OIL, LUBRICATING OIL, AND LABOR AT PUMPING PLANTS. I I ~1--~---~I-~ Costs for Year I Size I I Period of I __ _ Year I of Area I OperaWater I I I I I Per I Per I Engine Served I tion Pumped I Fuel Oil I Lub. Oil j Labor Total / 1 Acre I Acre-Foot I I I I and Gas , Served I Pumped I H. P. I Acres I Plant Acre-Feet I Dollars I Dollars I Dollars I Dollars I Dollars I Dollars I j \ \ Days I I 11933 I 360 II 5,798 I 48.2 15,607 1,070 I 222 I 971 1,160 930 2,263 2,554 1,768 2,228 \ 1934 I 360 5,798 I 55.6 16,588 Ii 1,138 256 I II , I 1935 360 5,798 37.4 11,210 666 I :11: 1936 360 I 5,798 I 33.5 12,627 792 172 160 200 155 194 1937 I 360 I 5,798 39.2 15,556 1,001 I :': 1938 I 360 5,798 23.1 I 8,414 503 1, I I I I 360 5,798 I 39.5 13,334 832 I I I 1 1 I I I 1933 I 540 9,478 49.7 28,609 1,970 I I I I I 1934 I 540 9,478 54.6 30,271 2,086 : I I 1 1 11935 I 540 9,478 35.3 21,385 1,184 I i 1936 I 540 I 9,478 41.7 26,071 1,430 I \ 1937 I 540 9,478 31.1 19,747 1,215 I I I I I 11938 I 540 Ill 9,478 27.6 18,796 964 II 1 1 540 9,478 40.0 24,146 1,475 ) I I I 277 305 197 286 243 201 252 1,276 I I 1,1ss 833 I 1,060 1 1 1,212 II 1,430 1,101 I 1,459 I 1,034 I 923 2,389 1,491 2,116 3,459 3,821 2,482 3,175 2,492 2,088 I I I I 1,193 I 2,920 I 0.39 0.44 0.30 0.38 0.41 0.26 0.36 0.36 0.40 0.26 0.33 0.26 0.22 0.31 0.14 0.15 0.16 0.18 0.15 0.18 0.16 0.12 0.13 0.12 0.12 0.13 0.11 0.12 0-, 0

PAGE 51

TABLE 17c.-COSTS OF ELECTRIC POWER AND L\BOR AT EVERGLADES EXPERIMENT STATION PUMP. --_ _ I _ __ _ __ _ Plant I I Year I I Everglades 1 103;3 Exp. Station! l!/84 I 1!!35 I!J 3 6 1937 1 l!J38 I Average I _ __ __ ___ ( Size of Moto1 H.P. 30 /lO 3 0 3 0 3 0 3 0 3 0 Ar e a Served Acres 162 162 162 1 80 180 180 171 I I Period of I I Cc s ts for Year OperaI Water I I I -1 -. . [ Per tion I Pumped I El ect ric Lub. Oil L ab or Total Acre Plant Day s 72.4 55.8 51.0 60.9 42.1 11.7 49.0 I I Power I I ' Served I Acre-Feet I Dollars I Dollars I Dollars I Dollars 1,670 1,499 1, 349 1,822 1,076 329 1,291 _ __ _ L I I I 78:i :, 5 5 I 7H0 , , 7 5 0 8:W 220 GGG 75 75 75 860 855 825 !Jll G!J8 Dollars 5.31 5.28 5.09 5.06 3 .88 I Per Acre-Foot Pumped I Dollars 0.51 0 . 57 0.61 0.50 0.65 01 I-'

PAGE 52

52 Florida Agricultural Experiment Station plants. No cost is shown for lubricating oil at the Experiment Station plant as the amount used is very small and no record is kept. The labor costs at the four oil engine plants include the wages of attendants and help used in cleaning screens and also that part of the superintendent's salary chargeable to supervision of these plants. The Experiment Station plant requires no regular attendant, so the labor item was estimated. Tables 18a, 18b and 18c show the total operating costs, includ ing fixed charges. The fixed charges are taken from Table 16. The annual maintenance costs have been estimated at 1 percent of the total investment in the plants. It is probable that $1 per horsepower per year would easily cover the engine repairs. The pumps and buildings require very little maintenance. The rec ords available are not sufficient to determine maintenance costs, but 1 percent is believed to be ample. No insurance is carried on the plants, and no taxes were included in the estimates of pumping costs. The total costs are also shown as unit costs per acre served, per acre-foot pumped and per acre-foot lifted one foot. Average costs as shown on the tables are based on the full six-year period and hence may not be the same as the average of the separate years. The costs per acre-foot pumped by Pelican Lake Unit 1 is less than that of Unit 2, due to the fact that more water is pumped by Unit 1. The costs, including fixed charges, however, do not vary much on the acre-served basis, being $2.52 for the one and $2.57 for the other. The levees of Unit 1 are often subject to greater pressure than those of Unit 2, due to high water on the outside, hence the ditches usually are not pumped as low as those of Unit 2 and the average lift is 0.4 foot less. The costs for East Pahokee Unit 1 are higher than those of Unit 2. However, the tables show that the average lift is greater for the first unit and the total depth pumped is less. Also the cost of the plant in relation to the acreage served is greater. The costs, including fixed charges, averaged $1.70 per acre for Unit 1 and $1.45 for Unit 2. These costs are considerably under those shown for the Pelican Lake plants, but it should be noted that the average depths of water pumped are considerably less, and the cost of these plants in relation to the acreage served is lower. The Pelican Lake plants are also less efficient than the East Pahokee plants.

PAGE 53

TABLE 18A . -T0TAL OPERATING COSTS OF PUMPIN(; PLANTS, INCLUDlNG FIXBD CHARGES. i [ Fixed I MainI I Costs for Year Av. Water ) Area Oils & I Plant Year Static Pumped Served ! Charges tenance I L abo r \ Total I Per Acre \ !'er Ac. Ft. j Per Ac . Ft. Lift I I I Amount Served Pumped L ifted 1 ft. Fe et I Acr e -F eet 1 1 Acres Dollars I Dollars 1 1 Dollars I Dollars I Dollars Dollars Dollars I ,:i MPelican Lake 1\133 3.3 HI, 181 I 3,379 5, 1 47 550 ;J,H12 8,88!J 2.68 0.4(j 0.14 I I 0 Unit No . 1 1 984 3.3 2:l,764 3,379 5,147 i)f,0 :1,1 1 :m H,fi27 I 2.85 0.41 0.12 C ;:s 1935 3. 7 11,10 ,5 3,379 5,14 7 r,r,o 2,1sn 7,88G 2.33 0.71 0.19 ~ "i ;2_ 1936 3.6 14 , 174 3,379 5,147 550 2,844 8,541 2 .5: l 0 .60 0.17 ~ ... 1937 1.0 rn,024 3,37() 5,147 i):,0 :i,:Wl !1,040 2.68 0.5G 0.14 ~ ;:,,(,:, UJ38 3.6 4,\!04 3 , 379 5,147 fifi0 1 ,:rn, 7,015 i 2.08 1.43 0.40 VJ C Average 3.5 14,85!1 3,379 5,147 :ifi0 2,8 0 :l H,500 2 .5 2 ,..., _ 0.57 0.16 &;" C '--+-. Pelican Lake 1 933 4.2 9,858 2,853 4,773 fi 10 1,!1 :1!) 7,222 2.53 0.7:3 0.17 ""' ;::,"' Unit No. 2 1934 -1. 3 14,287 2,853 -l,77:3 5 10 2,587 7,870 2.76 0 . 55 0 . 13 ti:l "' 1935 3.7 7,488 2,853 4,77:3 5 10 1.752 7,0!15 2.47 0.94 0.25 (,:, -:ci 1936 3.5 11,66 7 2,853 4,773 ii l 0 2,2!il 7,fi:l4 2 . fl-1 0 . 6fi 0.19 B" 1937 3 . 8 15,08!1 2,853 4,77:3 !il0 (,:, 2,li42 7,!l25 2.78 0.53 0.14 1938 3 .2 4,232 2,853 4,773 5 10 1 ,on (i,g55 2.2::l 1.50 0.47 Ave1agt! s.n 10,4::!7 2,853 4,773 510 2,040 7,324 2.57 0.70 0.18 01

PAGE 54

TABLE 18B.-TOTAL OPERATING COSTS OF PUMPING PL ANTS, INCLUDING FIXED CHARGES. I I I I I I Av. I Water I Area Fixed I MainI Oils & Costs for Year Plant Year I S : atic Pumped I Served Charges tenance Labor I Total I Per Acre I Per Ac. Ft. I Per Ac. Ft. ! Vft ! I Amount Served I Pumped I Lifted 1 ft. Feet Acre-Feet I Acres I DoLars Dotlars ,I Dollars Dollars Dol.ars I Dollars I Dollars I East Pahokee 1933 4.6 15,607 5,798 7,019 750 I 2,263 10,032 1.73 0.64 0.14 Unit No. 1 1934 4.7 16,588 5,798 7,019 750 I 2,554 10,325 1.78 0.62 0.13 i 1935 4.9 11,210 5,798 7,019 750 I 1,768 9,537 1.64 0.85 0.17 I 1936 4.2 12,627 5,798 7,019 750 I 2,228 9,997 1.72 0.79 0.19 I I 1937 4.5 15,556 5,798 7,019 750 I 2,389 10,158 1.75 0.65 0.14 I 1938 I 2.9 8,414 5,798 7,019 750 I 1,491 9,260 1.60 1.10 0.38 I I i Average I I i 4.4 13,334 5,798 7,019 750 I 2,116 9,885 1.70 0.74 0.17 I East Pahokee 1933 4.7 28,609 9,478 9,826 1,050 3,459 I 14,335 1.51 0.50 I 0.11 Unit No. 2 1934 4.7 30,271 9,478 9,826 1,050 3,821 14,697 1.55 0.49 0.10 I 1935 4.4 21,385 9,478 9,826 1,050 2,482 13,358 1.41 0.62 0.14 I I 1936 3 .6 26,071 9,478 9,826 1,050 3,175 14,051 1.48 0.54 0.15 I 1937 I 4.5 19,747 9,478 9,826 1,050 2;-492 I 13,368 I 1.41 0.68 0.15 I 1938 I 2.3 18,796 9,478 9,826 I 1,050 2,088 I 12,964 1.37 0.69 0.30 I Average I I I 4.1 24,146 9,478 9,826 1,050 2,920 I 13,796 I 1.45 I 0.57 0.14

PAGE 55

TABLE 18c.-TOTAL OPERATING C O S TS OF P UMP ING PLANT AT Ev E;.:Gf.ADE S EXPERIMENT STATION, INCLUDING FIXED CHARGES. -----/ I I : i / E l cct l'ic I Co~ ts fo r Year Av. Wat e r A rea I Fixed I MainPower J _ _ __ _ ___ _ _ _ __ __ _ Plant Year \ Stati c 1 1 Pumped \ Scl'vecl \Char ges I tenanc e I and I Total I Per Acre !P e r Ac.FL! Per A c .Ft. --~ _ _ __ L _ i_ft _ _ ___ ~ -~ -I I Labor Amount I Served Pumped I Lift ed 1ft. 1 1 1 1 Feet ltcre-F eet I Acres / Dollal' ; Dollar s \ Dollars I Dollar s Dollar s Dollars I Dollars Eve rglades / HJ3 3 / 2 . 0 I 1 ,67 0 lli2 I :rn:l ;;4 ! 860 \ 1,212 7 .48 0.7:3 0.36 Exp. Stati o n 1 1!)34 I 2.3 l 1,49 9 Hi2 1 :ll8 ;J4 85 5 I 1,207 7.45 0.81 0.35 1!)35 1936 1937 1938 Average 2.3 1,349 162 2.1 1,822 2 .2 1.7 2.1 1,076 329 1,291 180 1 8 0 180 171 I ;)18 : n 8 ; H S ;J4 34 3 1 8 ;;4 3 1 8 :l4 825 911 698 1,177 1 ,263 1,050 7.26 7.02 5 .84 2[)5 647 3.5!) 741 1,09 3 6.44 0.87 0.69 0 . 98 1.97 0.85 0.38 0.33 0.45 1.16 0.40 --I------~ -~----CJ a a

PAGE 56

56 Florida Agricultural Exp e 1 ' iment Station The fixed charges for the four oil engine plants average ap proximately two-thirds of the total costs of pumping. The four plants will also average about one gallon of fuel oil per acre-foot pumped. Most of the cultivated land of the northern Everglade s is served by pumping units similar to those of the East Pahoke e District and it is estimated th a t the depth pumped will average approximately three feet per year over the area served. Of the four plants con s idered, probably the costs shown for East Pa hokee Unit 1 will more nearly approximate the average costs for the pumped lands. In comparison with the value of crops raised, pumping costs are very low. In addition to the cost of pumping, proper maintenance of ditches and levees would amount to about $2 an acre per year. The cost tables for the Everglades Station plant show an aver age annual cost for electric power and labor of $ 4.33 per acre served and $0.57 per acre-foot pumped. The total costs, includ ing fixed charges, have averaged $6.44 per acre served, $0.85 per acre-foot pumped, and $ 0.40 per acre-foot lifted one foot. The fixed charges average about one-third the total cost of opera tion. The rainfall in 1938 was only 41 inches and very little pumping was done. Hence the low costs per acre served and the high costs per acre-foot pumped for that year. Very little pumping of the peat lands is done with electric power. Rainfall for 1937 was 58.44 inches; depth pumped for drainage was 6.0 feet; and evaporation is estimated at 3.5 feet. Seepage into the pumped area, based on the above data, was approxi mately 4.6 feet during that year of nearly normal rainfall. This is equivalent to an average inflow of about 500 gallons per minute into the area pumped by the Experiment Station plant. A higher water table without or a lower water table within an area will increase the s eepage. A comparison of the amount of pumping with the stages of the Hillsboro Canal clearly shows this effect. Average annual consumption of electric energy by the Experi ment Station plant over the six-year period has been 10,920 kilo watt hours and has cost $ 666. EFFICIENCY TESTS ON PUMPING PLANTS Overall effici e ncy tests were made at each of the oil engine plants in 1935 and the results are shown in Table 19. The dis charge of the pumps was measured with a Pitot tube and the fuel consum e d in an hour's time was carefully weighed. Th e static lifts are the difference in readings of the gages just out

PAGE 57

TABLE 19.-EFFICIENCY 'l'E'lTS OF OIL ENGINE PLANTS. I I Discharge Work Fuel Oil I Energy [ Overall Plant Pump Speed per Static of Pump by Used I Output Efficiency No. Minute Lift per Minue Plant per Hour I of Engine I of Plant ------" ----~--------• ! Revolutions! Feet Pounds H.P. Pounds ( Brake H.P. ! Percent , I Pelican Lake I i <:-IUnit No. 1 ---1 1 276 4.25 227,600 2fl.:J 37.4 74.9 I 31. Unit No. 1 " . " " . I 2 270 4.72 201,300 28.3 34.5 69.0 I 33. ("'J 0 ..., Unit No. 2 "" . 1 272 3.22 232,100 22.6 :rn.8 61.6 29. ,,.., <-+Unit No. 2 ... 1 269 5.77 182,700 :32.0 36.4 72.9 35. ""' Unit No. 2 2 290 5.95 227,600 41.1 46.8 93.6 35. Unit No. 2 2 275 3.27 2:i4,:~oo 2:~.2 31.2 62.4 30. "' ;:s East Pahokee <:-IUnit No. 1 1 250 5.80 441,500 77.6 73.7 147.5 42. Unit No. 1 1 227 6.15 :JDl,500 72.9 66.1 132.3 44. v:i Unit No. 1 1 202 5.96 :l01,800 54.6 54.0 108.0 40. 0 "' Unit No. 1 1 177 5.96 240,000 4:3.4 41.4 82.8 42. Unit No. 1 2 248 5.14 457,000 71.2 70.5 141.0 40. 0 Unit No. 1 2 226 5.16 :rn5,100 61.8 57.2 114.5 43. -,,..._ Unit No. 2 1 257 4.99 48:~,500 73.2 75.5 151.0 39. <:<:, Unit No. 2 1 227 4.91 418,200 62.3 57.2 114.5 44. t".tj Unit No. 2 . " 1 200 4.94 356,000 53.3 46.1 92.2 46. Unit No. 2 1 175 5.16 27\J,200 43.7 38.6 77.3 45. <:<:, ""' Unit No. 2 1 150 5.26 148,(;oo 23.7 29.1 58.2 33. Unit No. 2 3 256 5.35 488,000 W.2 71.3 142.6 44. <:<:, Unit No. 2 3 256 6.10 480,000 88.8 79.0 158.0 45. ,:,, Unit No. 2 . 3 226 6.12 401,100 74.4 63.1 126.2 47. Unit No. 2. 3 200 6.00 336,500 61.3 47.5 95.0 52.* Unit No. 2 .......... .. ....... 3 176 6.02 263,500 48.1 39.2 78.4 49. -------------------o, *Value probably too high. -'1

PAGE 58

58 Florida Agricultural E x periment Station side the screens at either end of the plant. The u s eful work done by the plant, or water horsepower, is based on the pump discharge and static lift. The energy output of engines is esti mated on the basis of 0.50 pounds of fuel oil per brake horse power. The overall efficiency is the ratio of the water horse power hours to the indicated horsepower hours or energy used in the engine. The mechanical efficiency or ratio of the brake horsepower to the indicated horsepower is estimated at 80 per cent. The term "plant" in Table 19 refers to a complete pump and engine unit. Each plant has two or three such units. It is evident that the East Pahokee plants are much more efficient than the Pelican Lake plants . The East Pahokee pumps are of larger size and probably more recent design. Efficiencies ba s ed on fuel consumption and brake horsepower are necessarily only approximate. In October, 1937, several efficiency tests were made on the Experiment Station pump. The power input was mea s ured by the watt-hour meter and the discharge with a standard weir. The motor is connected to pump with V-belts. The motor effi ciency used was 88 percent and the belt efficiency 94 percent. The static lift was measured inside the pump hou s e. The re s ults were as follows : Pump S tatic Pump W o rk Energy Efficienci es Sp ee d Lift Discharge D o ne Used O ve rall Pump R.P . M . Fe e t Sec. Feet H.P. H.P. Per ce nt P er cent 57 4 4 .33 17.95 8. 82 26.2 34 41 4 4 2 3 . 9 4 11.72 5.24 15.1 3 5 42 2 92 3 .46 5.00 1. 96 7.9 25 3 0 The pump used in these efficiency tests was a 24-inch vertical turbine driven by a four-speed Westinghouse induction motor rated 30 hor s epower at 1,180 revolutions per minut e . A large number of pumps of this type ar e used in the northern Ever gl a de s , but only a few ar e operated by electric power. This pump was later re-conditioned and the di s charge w as improved. Capacity of Pumps.-A 12-ye a r record of rainfall at th e Ever glade s Experiment Station s how s th e following aver a g e periods between rains : S ize of Rains Av. Number per Yr. 1.0 inch or more . .. . ... ...... . ... . ... . ...... ... . 1. 5 inch or more . ...... ........ . . . . . . . . . ..... . . . 2 .0 in c h or mor e ....... ... . . .. . . . . ... . . . .. . ... . . 2. 5 inch or mor e ....... .. . .. . . . .... . . . . . . . ..... . 3 .0 i nch or more ..... . .. ...... . .. . . .. . ... ... . .. . 3 . 5 i nch or m o r e ....... . . . .... . . . . ... . . ..... ... . 4. 0 inch o r mor e .......... . . . .. .... . . .. . ....... . 4 .5 in c h or more .. . .... .... .. . . .. . ............. . 5 .0 inch o r more .. . .... . .. .... .. . . . 17.2 8.1 4.0 2. 3 1.4 1.0 0.5 8 0 . 33 0.2 5 Av. P e ri o d in Month s 0.7 1.5 3 .0 5.2 8 . 5 1 2 .0 20.6 36. 4 4 8 .0

PAGE 59

Water Control in the Soils of th e Everglades 59 The above figures indicate that excessive rains are not very frequent. The probability of rains of two inches or more is four in a year; of 3.5 inches or more is one in a year; and of 5 inches or more is one in four years. Many of the heavy rains occur during the three summer months when there is little or no farming. Nearly half of the rains of two inches or over occurred in that period. The damage from excessive rains is reduced to a considerable extent by the high absorptive capacity of the peat soils. Under usual conditions an inch of rain will raise the water table about six inches. If the water table were two feet deep, about four inches would be required to saturate the soil. How ever, as the top soil is changed by cultivation and weathering, the seepage movement is retarded and water will remain on the surface for a considerable period with the ditches at a low stage. Heavy rains sometimes occur when the water table is high and the soil wet from previous small rains. Certainly not more than two inches should be the allowance for the decrease in pump capacity on account of soil absorption. On this basis pumps with a one inch capacity would handle all rains up to three inches and the 12-year record shows only 11 rains of three inches or more outside the summer months. With pumps of 2-inch capacity, rains up to four inches could be cared for in this area, and only six rains of four inches or more have occurred outside the sum mer. With a 3-inch pump capacity a 5-inch rain could be cared for. The 12-year record shows three rains of five inches or more and one of these fell in the summer period. The Wood-screw type of pumps used in the larger drainage units have a capacity of approximately one inch in 24 hours. Experience indicates that this rate of discharge is sufficient for sugarcane. During recent year s nearly all the pumps in stalled to s erve land used mainly for truck crops have had capaci ties varying from 1.5 to 3.0 inches. Th e Experiment Station pump has served from 160 to 180 acres in recent years and the record shows that a 2-inch discharge has been sufficient except in the case of very exceptional rains. For rains exceeding 3.5 inches a greater rate of run-off is u s ually needed. Only 14 such storms have occurred in the last 15 years and five of these have been in the three s ummer months. Pumps serving truck lands should have a capacity of two to three inches. The proper depth of run-off will depend on the value of crops raised and also on the area drained. A run-off of more than three inches probably could not be justified on economic grounds. Private pumping

PAGE 60

60 Florida Agricultural Experiment Station units within a large drainage system are of value in controlling the water table on individual farms, but the run-off provided by such units should not greatly exceed that of the main system. FARM DITCHES District laterals are usually spaced a half mile apart along section and half section lines . Farm ditches are spaced from 1,320 to 660 feet apart, the c~oser spacing being generally used for truck crops. The depth of run-off which these ditches will carry should b e equal to that provided by the pumps. The ditch banks should have a to 1 side slope. As the land is practically flat, a three-in c h fall per mile is commonly used in calculating ditch sizes. The maintenance of ditches is an important problem. Water plants such as hyacinths or moss commonly cover or fill the channe'.s and Para grass grows readily on the banks. Such growth greatly reduces the capacity of a ditch. In addition to these, a soft soupy sludge collects in the bottoms. These growths and deposits should be removed at regular intervals. The ditch banks should be sodded to prevent the growth of weeds and Para grass. The sludge in the bottoms of ditches can best be removed with a pump type of ditch cleaner. MOLE DRAINAGE Subdrainage and subirrigation is accomplished by means of moles. 7 These are formed by drawing a 6-inch, bullet-nosed cylinder through the soil between farm ditches. The depth is commonly 30 inches and the spacing from 12 to 15 feet. The resulting hole is about 4 inches in diameter. Cleaner mole holes result if the moling is done when the water table is below the mole depth. Spring is the best time to do this work, for it then requires less pumping to hold a deep water table. If the mole work is well done, the lines will probably give sa tisfactory sub-drainage for a period of from five to eight years. At the end of the effective period the field can readily be re-moled. The cost of such work is about 50 cents per acre. Fol'.owing a heavy rain the water table in a moled field will drop more rapidly than in a similar field not moled. Some obser7 Allison, R. V. Movement of undel'ground waters. Fl o rida Agr. Exp. Sta. Ann. Rpt. 1928: 117R-118R.

PAGE 61

Fig. 10.-Mole entering so il at s id e of ditch. Note vertical cut in bank from mole to surface of the soi l where the blade that precedes the mole has entered. vations at the Everglades Station indicate that after a rain has saturated the so il the water table in a moled field will drop a foot in about one third the time required for a field without moles. In a pumped area subject to pressure, due to higher water outFig. 11.-Mo'ing machin e in operation. The mo l e (as s hown in Fig. 10) is being drawn through the so il at the bottom of a heavy blade carried at the end of the eye-beam and dir ect l y beneath the man on the machine at the right.

PAGE 62

62 Florida Agricultural Experiment Station side the dikes, the water table in the fields will usually stand substantially higher than that in the ditches. In such cases the mole drains will tend to level out the water table and reduce this difference. As far as possible it is best to install the mole lines before digging the farm ditches, for in this case the moles will have outlets in ditches at either end, whereas if the work is done later each line will have a dead end. Also the depth should not be less than 30 inches, for experience has shown that shallower lines may be closed up by the weight of farm machines. WATER TABLE STUDIES THE WELL LINES In the spring of 1932 a number of well lines were established to record the rise and fall of the ground water elevations in cer tain areas near Lake Okeechobee. For several years prior to 1932 the Everglades Station made weekly readings along several lines on the station property. Two of these lines extended in a southwesterly direction from the Hillsboro Canal and across several farm ditches located 240 feet apart. The data indicated that with a high level in the Hillsboro Canal the see page gradient diminished rapidly with distance from the canal. On irrigation tests the data also showed that the plot water tables were substantially below the high level in the ditches. Line "G," mentioned in this report, was one of these old lines and the subsequent data were consistent with the earlier measurements. A third line extended from the Hillsboro Canal across virgin land owned by the Experiment Station. This line was relocated in 1932 and designated as Line "A" and read ing s were continued for several years. The location of the lines as established in 1932 are shown on Figure 1. A chart for each line shows the fluctuations of the wat er table in a typical well over a period of several years. The rainfall, lake or canal levels and other data affecting the ground water levels are also shown. A profile for each of the lines shows typical ground water curves, the depth of peat, and the distance between wells. Charts and profiles have been pre pared for 12 lines designated as A, B, C, D, E, G, M, 0, Q-R, S, T, and U. A map showing ties to section corners and a short discussion of the water table variations has been prepared for each of the lines.

PAGE 63

~ ,1 6 1 5 ' ,4 .~ 13 -~12 so Water Control in the Soils of the Everglad es 63 In this report, data for only a few of the more important lines are presented. Charts and profiles for the remaining lines may be secured from the Soil Conservation Service, Washington, D. C. Well Line D.-Line D (Fig. 1) begins at the old levee on the south side of Lake Okechobee and extends south across the east portion of Sections 5 and 8 ; Township 44, Range 36, to the Florida East Coast Railroad. The location is about a quarter mile west of the east line of these sections, and is in the South Shore Drainage District. A road ditch along the north side of Section 8 provided some drainage for the land. The drainage f eb. J une , Ju l y Aug. Oc t , ,.....4.p pro iimatl! gr cr(ffld su~!___ l'1e l " II 4 . 0 ia " Fig. 12 . -Hydmgraph s of Wells 8 and 27, Line D, and Lake Okeechobee; rainfall near Line D.

PAGE 64

1 6 1 3 1 2 2 0 1935 6 . 84 2 . 64 I.QI 1 9 3 7 I I f\ k ....... ! ... .. .. I I ~ ..... , . , iv ~ ----. .. I\ I ' , ' ' 1, '---s I ' -, I ' I ' '_I '" I I ' I , .... ,_, --J ' ' 4.45 3 . 88 -..... ,,.. ... _ _ .,,.../ ,/ ' .1 L ' L 11 ,J I i I I J 3 . 77 0 99 644 5 . 69 3 . 55 I 6 . 9 5 0 33 0 .1 4 4 87 Fig . 1 3. -H yd r og raph s of We ll s 8 an d 27, L i n e D , and L ake O k e ec h obe e; r ainfall near Li n e D.

PAGE 65

Water Control in the Soils of the Everglades 65 district had no permanent pump installations until the spring of 1938, when a 35,000-gallon pump was installed. Land south of the railroad line is in the South Florida Conservancy District, which is drained by pumps. The water table along Line D is probably lowered somewhat by see page into this pumped land during the summer and fall months. The soil is Okeechobee (custard apple) muck underlaid with limestone at an average depth of 7 . 5 feet. During the period of the record the land was used for truck crops. The drainage was not very good until pumps were installed in 1938. Well records on this line began in May, 1932 , and readings were made about once a week until July, 1934, when automatic gages were installed at Wells 8 and 27. Figures 12 and 13 show the variations in water tables at these wells and also the stages of Lake Okeechobee. The rainfall shown is the average of that at South Bay and Lake Harbor. Figure 15 shows a profile along line D and the depth of soil. The lowest s tages in both wers occurred in May, 1932, when the lake was at a record low stage. The low stages were pre ceded by nearly a year of very low lake levels and by more than a year of subnormal rainfall. Well 8 is located 1,000 feet south of the old Everglades Dis trict levee and 1,700 feet south of the new Government levee. The stages in this we] are strongly affected by the lake level. Near the end of the dry season in the latter part of May or early June the well water has averaged about 0.7 feet below the lake and the extreme differences have ranged from 0.5 to 1.5 feet. The corresponding lake elevations have varied from 12.5 to 15.8 feet. The extreme differences between lake and well stages in January averaged 0.6 feet and ranged from 0.4 to 1.0 feet. The low lake stage for January, 1933, was 14.5 and for January of the years 1934 to 1938 was approximately 16 feet. Well 27 is located 5,000 feet south of Well 8 and 6,700 feet from the new levee. The extreme low stages in the latter part of May or early June averaged 2.3 feet below the lake and varied from 1.0 to 3.2 feet below. The extreme low stages for January averaged 2.2 feet below the lake and varied from 1.6 to 2.6 feet below. Wells 8 and 27 are almost one mile apart. The extreme low stages in January for the years 1933 to 1938 show an average difference of 1.5 feet and those for May or June a difference of 1.8 feet. This greater slope at the end of the dry season is

PAGE 66

66 Florida Agricultural E x periment Station doubtless due to the fact that evaporation and seepage have lowered the water table in land south of the cultivated area. On account of variation in rainfall and other conditions, it is difficult to determine the effect of changes in lake stage on the water table in the outer lands. Although a comparison of lake stages with the stages in Well 27 do not show a consistent differ ence, it i s evident that a substantial change in lake elevation has s ome effect on this well. However, the effect appears to be small and it seems probable that an increase of two to three feet in the normal lake height would cause no substantial increase on the water table several miles out. The new levee was completed across the end of Line D in the summer of 1935. Beneath the levee are two trenches which were excavated to rock and then refilled with marl and shell. The purpose of the one near the inner toe is to prevent fires from reaching the organic materials beneath the fill and that of the other is to decrease seepage. A comparison of the stages in Well 8, before and after the levee was completed, indicate that the construction of the levee has had little effect on the water table near this well. Well Line E.-Line E begins at the edge of Lake Okeechobee, about 1 miles northeast of Pahokee, in Section 8, Township 42, Range 37, and extends in a southeasterly direction through the Boe farm to the Florida East Coast Railroad. The line crosses a sand ridge at a point 610 feet from the levee. Well 6, at the east toe of the ridge, is 710 feet from the levee and Well 10 is 1,440 feet from the levee. East of the railroad is a low area once covered by Pelican Lake. This is now drained by pumps and as a result the water table along this line is lowered by seepage into this low area. The soil east of the s andy ridge is deep Okeechobee "custard apple" muck and is used for truck crops. Readings along this line began in . May, 1932. In July , 1934, an automatic water level recorder was installed at Well 10. The principal purpose of the line was to show the effect of lake stages on the water table in the adjacent land. Figure 14 shows the water levels in Wells 6 and 10, lake stages, and rainfall for the first half of the years 1935 to 1938. This period is used because it includes the dry part of the year when the rainfall and water tables are at minimum and the effect of lake stakes are most apparent. Figure 15 shows a profile along this line. In January , with a normal lake elevation of about 16 feet, the

PAGE 67

JANUARY I FEBRUARY I MARCH APRIL MAY JUNE JANUARY I FEBRUARY I MARCH APRIL 'MAY JUNE 1935 1936 16 1 ... ," ... ...... ... / .. , Appro~ir'note ground s urfocb near wel l no . 1 0 "' .... -, . .,. .. ... .. / a-rs 0ell6 --t g:; i .:i _,_,4 .,... w _.,..._ -. I ...... . ...... ,....-w e11 1 0 -_, ---I --: 13 r -, ' ' ( C"':i 12 -~ -; ~ ~; + C ;:::: 2 N--; St "" I I I~ I ;:::: CI:.:.=, I I I.~ .,... 0 II J ! 0.10 3.0 0 0 . 30 7. 79 064 7.63 VJ 193 7 /938 C ~ ~ (, ' .. I I 1 .... "' 16 Ave roc;ie _ ground s u r ac e 11eor 'well no.IQ C ~L a ke Okeechobee ~-=1 5 Nr ' ' ;:,-a !~14 ... i ' ' . .. . . . I 1 ' . . (':) w I . . we116 t
PAGE 68

LI NE D GROUND PROF I LE 24 ,-------,----,---~--~-----,-----,----,----,---~--.---,-----,----,----,---~-----,.---,---,---, . 1 2 , o ,______. 81-.. 0 0 ,00 -I-'1 ,0Q B, OO 1 2 "6 2 0•/J 0 2 4 0 28 0 32, 00 36, 00 L INE E GROUND PROFILE 40 00 44 00 ---4 8 5 2 00 56 00 60,0 0 64 0 68,00 24 ----I------------1 ---1 --t-+ -+-+-t---1 --+ -+ +---+---t---1---+---+ +--+ ----+-f---1 4 --12 ~---# O f-_ _ __ +-+ __ +---+-c,--,--t-----l-+ f-tt-..--+ -+-+--------,---1 ---t---t----+--+---t------l >-_-_ _ _ + f--------; .; =-==/ _ .. -1H-------+ --+----+---.. -----1-i------t---t----t -i-l .),0(1 s, ,_,o 1 2,00 16 0 2 0-0 0 24, 00 2s, oo 32, 00 36, 00 4 0 0 4 oo 4 f! oo s 2-o o 56-0( 1 150.ci n e,4 , 0 0 sa ,oo Fig. 15.-Profiles of Lines D and E.

PAGE 69

W ate1' Control in the Soils of the Everglades 69 lowest readings at Well 6 have averaged 1.6 feet below the lake and those at Well 10 have averaged 2.6 feet below lake level. The difference of one foot between these wells is equivalent to a slope of 7.2 feet per mile in the seepage gradient. The extreme low readings in these wells occur near the end of the dry season in May or early June. With a lake elevation of about 15, the low readings in this period have averaged 2.4 feet below the lake at Well 6 and 3.7 feet at Well 10. The difference of 1.3 feet between these wells is equivalent to a slope of 9.4 feet per mile in the seepage gradient. This increase of slope between January and May or June is due to a lowering of the water table in the adjacent lands by seepage and evaporation. The new levee across the head of Line E was closed in October, 1935. Beneath the fill are two trenches which were dug to rock and refilled with marl and shell. It is probable that very little seepage can penetrate these fills. A study of the well readings along Line E indicates that the new levee has had no substantial effect on the water table in adjacent lands. This and other obser vations appear to show that the seepage movement between the lake and adjacent lands takes place through the porous limestone and sand beneath the peat rather than directly through the peat deposit. On account of the variation in rainfall and amount of pump ing, it is difficult to determine the effect of changes in lake stage on the water table in this area. A substantial change in lake stage will raise the water table at Well 6, but the raise is con siderably less at Well 10. The effect certainly decreases with distance from the lake. A change of several feet from normal lake level would probably have no substantial effect on the water table a few miles from the levee. As previously noted, the water table at Line E is affected by the low land in the old Pelican Lake area. The water table along Line D is the more typical of the general condition around the lake. The lake level is regulated as nearly as possible between 14 and 17 feet. The average stage of 16 feet is probably the most favorable height for present agri cultural conditions. However, as the farm lands continue to sub side a lower level may become desirable. As the water table in the peat land near Lake Okeechobee is affected by rainfall, pumping, lake and canal stages, it is diffi cult to draw general conclusions from a study of fluctuations along well lines. The study, however, shows that the water table in a field is usually not the same as that in the ditches. Follow

PAGE 70

70 Florida Agricultural Experiment Station ing a rain the profile of the water table between ditches shows a very flat curve with a rather sharp drop to ditch levels near the ends. This curve will slowly flatten as pumping continues and during dry spells with no pumping may reach a point about one-half foot below ditch levels. Fields adjacent to a levee with high water stage outside may have a water table close to the surface when the interior drainage ditches are at a low level. This pressure causes a seepage fl.ow through the porous rock or sand and thence upward into the fields. If the water table outside a dike were held a foot above the land within it is prob able that a strip about 100 yards wide would be too wet for satis factory farming even though the ditches were held at a low level by pumping. A small ditch along the toe of a dike will substan tially depress the seepage gradient. WATER TABLE PLOTS To determine the effect of water table depth on crop yields eight water table plots were established at the Everglades Sta tion. The plots are approximately 100 by 240 feet in gross size, and are surrounded by ditches on three sides. Mole drains 15 feet apart extend across each plot and connect the side ditches. Two 1,000-gallon pumps with electric motors maintain the de sired water tables at near-constant levels. Two of the plots are equipped with overhead spray lines. One-third of each plot has been planted to sugarcane, one-third is used for truck crops, and the other third is used for grass or forage crops. The water tables in the several plots varied from approximately one to three feet. During the years 1937 and 1938 water table depths of 1.0, 1.5, 2.0, 2.5, and 3.0 feet were held as nearly as possible in the particular plots. For about 18 months before operation the water table was approximately the same in the whole area and during this period corn was grown on all plots to determine their relative produc tivity under conditions of equal water tables. The maintenance of definite water tables at different levels was begun in Novem ber, 1935. After a few more crop years a complete report will be prepared covering the crops as well as the soil conservation phases of these water table experiments. The results so far obtained indicate that a 1.5 to 2.0-foot water table is best for truck crops; that grasses do well on a table held at from 1.0 to 2.0 feet; that some

PAGE 71

Water Control in the Soils of the Everglades 71 varieties of sugarcane produce good yields on a 1.0 to 1.5-foot table while other varieties do better on a deeper table. The canes producing best on a high water table are of partic ular value from a soil conservation standpoint, for the higher the water table the less is the surface subsidence of the land. SUMMARY An outstanding need of the Everglades is a comprehensive plan of water conservation whereby the water now wasted could be used to maintain a higher water table in the idle lands and thus decrease the losses from subsidence and fires. This should also provide for a definite system of outlet canals for all land of agricultural value so that an orderly development could be achieved. Under present conditions expansion is taking place without such a plan, thus complicating the problem of providing a consistent scheme for the whole area. SOILS The major portion of the peat lands of the Everglades consists of the partially decayed residue of sawgrass deposited over a period of thousands of years. A field sample of this soil when oven-dried loses about three-fourths of its weight. The ash or mineral content is about 10 percent of the dry weight. After drainage and cultivation for a period of 10 to 15 years the dry weight of the top 18 inches of soil about doubles. The Okee chobee (custard apple) or plastic muck on the east and south sides of Lake Okeechobee has a mineral content of 35 to 70 percent of the dry weight. Between the "Everglades" peat and the plastic muck is an area of Okeelanta peaty muck (willow and elder) land with a mineral content intermediate between the peat and the muck. SUBSIDENCE Subsidence of peat soils is due to natural oxidation, fires, shrinkage and compaction caused by lowering the water table and cultivation. The loss in elevation of the drained deep peat lands in the northern Everglades has been approximately five feet since drainage. About 11/2 feet of this loss is accounted for by the increase of dry weight in the upper portion of the soil. The present rate of loss is approximately one inch per year. The loss is about proportional to the average depth of

PAGE 72

72 Florida Agricultural Exp e riment Stet.lion water table. Okeechobee (custard apple) muck subsides some what slower than sawgrass land. S EEPAGE The rate of seepage through virgin sawgrass peat soil is very slow in a horizontal direction. However, after cultivation and weathering, the vertical movement through the top portion of the soil also becomes very slow due to changes in the soil struc ture. There appears to be a considerable movement of the seep age water through the porous rock and sand beneath the peat. Pumping records show that a large part of the water pumped enters the drained area through seepage. RAINFALL, EVAPORATION AND TEMPERATURE In the northern Everglades the average rainfall for the four month period from June to September is approximately 60 per cent of the mean annual amount. A 14-year record at the Everglades Experiment Station shows an average annual rainfall of 57.3 inches. The greatest intensity for a one-hour period was 3.25 inches. Estimates based on tank experim en ts with sugarcane indicate an annual evaporation and transpiration from cane fields of 42 to 45 inche s per year. Similar experiments with sawgrass showed an annual loss of 84 inches from a dense s tand of grass and 68 inches after the stand had deteriorated to some extent. As the average stand over the sawgrass areas of the Everglades is less dense than that in the experimental tanks, it is estimated that the loss from such areas would approximate 60 inche s per year. The lowest temperature recorded in the Everglades was 9 F . at Shawano on virgin sawgrass land. A comparison of low tem perature records indicates that minimum readings will be about 4 degrees higher on cultivated land than on nearby virgin land at temperatures below 38 F. WATER CONTROL HY PUMPING Pumps are essential for the proper control of water in th e northern Everglades. The sub-drainage districts of this area have a total rated pumping capacity of 4,200 seco nd-feet. In addition to these sub-district pumps there are a large number of small pumps serving private farms. The area served by

PAGE 73

Water Control in the Soils of the Everglades 73 pumps in the northern Everglades is approximately 100,000 acres. Most of the sub-districts are served by large pumps of the Wood-screw type ,vith a capacity of approximately one inch over the area served. Records have been kept for four pumping plants of this type over a period of six years. The average static lifts of these plants varied from 3.5 feet to 4.4 feet. The fuel oil con sumption ,vas approximately one gallon per acre-foot of water pumped. The mean annual depth pumped over the six-year period varied from 2.3 feet for one of the larger units to 4.4 feet for one of th e smaller units and the total cost of pumping, including fixed charges , vari e d from Sl.45 to S2.57 per acre served. The fixed char g es amount e d to about two-thirds of the total cost of pumping. The annual cost of el e ctric power at the Everglades Experi ment Station plant, over a p e riod of six years, averaged S3.90 per acre s e rved and 6.1 cents per k.w.h. used, and the average period of plant operation was .J.9 day s per year. The amount of pumping depends very much on the s tage of the Hillsboro Canal. as this affects th e rat e of seepage into the pumped area. A pumping capacity of two to three inches is recommended for areas of mod e rate s ize us e d to grow truck crops. The prop e r depth will depend on the kind and value of crops grown and also on the size of ar e a drained. DITCHES AND SUB-DRAINAGE Collection ditches should have a total capacity equal to that of the pumping plant , and s hould be kept clean of hyacinths, moss and grasses _ , ,vhich greatly reduce the channel capacity. Mole lines , usually s paced 12 to 15 feet apart and 30 inches deep, provide an inexpensive sub-drainage system and increase the rate of drop of the water table after heavy rains. WATER TABLE STUDIES Record s from well lines near Lake Okeechob ee indicate that the new lake levee has had little or no effect on the seepage gradient from the lak e to adjacent lands. A continuous water table record has been kept at a well 6,700 feet south of the new levee near Bean City. During the dry periods from January to June with the lake at a 15 to 16-foot stage the water table at this well was approximately 2.3 feet below the lake. A sub stantial change in lake level appear e d to have a small effect at

PAGE 74

74 Florida Agrfrultural Experiment Station this point, but at a distance of several miles from the lake it is believed the lake effect would be negligible. Water table studies at the Everglades Experiment Station in dicate that truck crops give best results when the depth to water is 1.5 to 2.0 feet, while grasses and some varieties of sugarcane do well when the water in the soil is maintained at an appreciably higher level. Such considerations, under practical conditions in the field, shall have to take into account such features as trans portation in the field, plant anchorage in relation to wind damage, and many others.