Hydrologic effects of area B flood control plan on urbanization of Dade County, Florida ( FGS: Report of investigations 47 )

STATE OF FLORIDA
STATE BOARD OF CONSERVATION
DIVISION OF GEOLOGY

FLORIDA GEOLOGICAL SURVEY

Robert O. Vernon, Director

REPORT OF INVESTIGATIONS NO. 47

HYDROLOGIC EFFECTS OF AREA B FLOOD
CONTROL PLAN ON URBANIZATION OF
DADE COUNTY, FLORIDA

By
F. A. Kohout and J. H. Hartwell
U. S. Geological Survey

Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
CENTRAL AND SOUTHERN FLORIDA FLOOD CONTROL DISTRICT
and the
DIVISION OF GEOLOGY

1967

FLORIDA STATE BOARD

OF

CONSERVATION

\AQto,-V

CLAUDE R. KIRK, JR.
Governor

TOM ADAMS
Secretary of State

BROWARD WILLIAMS
Treasurer

FLOYD T. CHRISTIAN
Superintendent of Public Instruction

EARL FAIRCLOTH
Attorney General

FRED O. DICKINSON, JR.
Comptroller

DOYLE CONNER
Commissioner of Agriculture

W. RANDOLPH HODGES
Director

LETTER OF TRANSMITTAL

TJlorida geologficat S rveC

Tallahassee
May 24, 1967

Honorable Claude R. Kirk, Jr., Chairman
State Board of Conservation
Tallahassee, Florida
Dear Governor Kirk:
The Division of Geology, of the State Board of Conservation, is pub-
lishing as Report of Investigations No. 47, a report prepared by F. A.
Kohout and J. H. Hartwell entitled "Hydrologic Effects of Area B Flood
Control Plan on Urbanization of Dade County, Florida."
The rapidly expanding megalopolis of South Florida requires that
detailed knowledge be developed on the geology and hydrology of this
area. This knowledge must be directed particularly to the extent and
depth of flooding following unusual rainfall, and must recognize the
economics of the cost of developing additional properties for real estate
developments that cover surface zoning for human utilization. This
report seeks to provide these answers and when the metropolitan areas
along the Coast must be expanded to the west, all the way to the fence
formed by the conservation levees, engineering and planning personnel
will have available the required design data.
Respectfully yours,
Robert O. Vernon
Director and State Geologist

Completed manuscript received
May 24, 1967
Printed for the Florida Geological Survey
By The St. Petersburg Printing Co., Inc.
St. Petersburg, Florida
1967

CONTENTS

Abstract .......... ......................................................... ................................................. 1
Introduction .............................................................................................. ............................. 2
General hydrologic situation and overall flood-control plan ......................................... 4
Area B plan ..................................................................................... ............................... 6
Details of the Area B plan ................................................................................................ 9
Rainfall intensity related to flooding ............................. ................ 11
Quantitative estimates of previous investigations ............................................... ....... 15
Acknowledgments ..................................................................................... ........................ 16
Future water needs and availability ................................. ............................................ 16
Geologic and hydrologic environment ................................................................................ 20
Present and future land-surface altitude ............................................. ....................... 22
Transmissibility of the aquifer ....................... .......................................................... 25
Effect of flood-control project on ground-water level .................................................. 25
Ground-water fluctuations .............................................................................................. 25
Comparison of high-water periods ............................ ... ....................... 27
Comparison of low-water periods ............................ ...................................... 27
Canal discharges .................................................................................................................... 32
Stages and discharges in the Miami Canal ........................................................... 32
Contributions to flow in the Miami River from
Conservation Area 3B, Area B, and Area A ........................................................ 37
Total surface-water outflow from Area A .................................................................. 39
Evaluation of the Area B flood control plan .......................................... ........................... 42
W ater-level maps .................................................................................................................. 43
Analog study ..................................................................................... ............................... 46
Boundary conditions ........................................................................................................ 47
Results of the analog study .................................................................................................. 50
Borrow canals without isolating control dams ............................................................ 50
Borrow canals with isolating control dams ............................. ............................... 52
Comparison of the analog models ................................................................................ 55
Summary .............................................................................................. .................................. 56
References .............................................................................................................................. ....... 60

ILLUSTRATIONS

Figure Page
1 Physiographic provinces in Southern Florida ...................................... ........... 3
2 Canal and levee system of the Central and Southern Florida Flood
Control Project in Southeastern Florida ......................................................... 5
3 Intake of pumping station S-7 which has a capacity of 2,490 cubic feet
per second under design conditions .................................................................. 7
4 One of the 131-inch impellers at pump station S-7 .......................................... 7
5 Major features of existing and proposed canal and levee system in
the M iam i area .............................. .......... ...... ............ ..................................... 8
6 Accumulation of rainfall in 1947, 1959, and 1960 ............................................ 12
7 Rainfall for September 1960 following the passage of Hurricane Donna
and tropical storm Florence in the Miami area .............................................. 13
8 Estimated water use between the years 1930 and 1995 for Dade County
and the Florida K eys ..................................................................................................... 17
9 Primary and secondary canal system in 1964 and locations of recording
observation wells related to the investigation, in the Miami area .................... 21
10 Generalized altitude of land surface in Area B ................................................ 22
11 Altitude of bed rock in Area B .......................... .. ....................... 23
12 Assumed altitude of compacted land surface in Area B after 100 per-
cent loss of black-muck soils above +3 feet nms and 50 percent
compaction of muck soils below +3 feet msl ................................ ........... 24
13 Monthly trend of water-level fluctuations in selected wells related
to rainfall, 1940-63 .................................................................................................. 26
14 High-stage water levels in the Miami area October 11-12, 1947. Canal
C-100 did not exist and C-1 was not improved in 1947 ............................................ 28
15 Highest water-table altitude in the Miami area in September 1960
after passage of Hurricane Donna and tropical storm Florence. Canal
C-100 did not exist and C-1 was not improved in 1960 ............................................ 29
16 Record low stage of water table prior to installation of control dams
in the Miami area, May and June 1945. Canal C-100 did not exist
and C- was not im proved in 1945 .............................................................................. 30
17 Low stage of the water table in the Miami area in May 1962 and
extent of salt-water encroachment .............................................................................. 31
18 Monthly mean discharge in the Miami Canal at Hialeah (Sta. H)
and N.W 36th Street (Sta. I) 1940-1963 .................................................................. 33
19 Locations of gaging stations and drainage areas of major canals in
the M iam i area ........................................................... .............................................. 35
20 Daily stage and discharge in Miami Canal, 1961-63 ................................................ 36
21 Discharge contributions to the Miami River at Brickell Avenue front
Conservation Area 3B, Area B, and Area A ............................................................ 38
22 Monthly runoff for the six canals draining Areas A and B ................................ 41
23 Water levels in feet above (+) or below (-) existing land surface
during September 1960, subsequent to passage of Hurricane Donna
and tropical storm Florence .......................................................................................... 44
vi

ILLUSTRATIONS-Continued

24 Water levels of September 1960 in feet above (+) or below (-)
assumed compacted land surface ................................... ........... ............... ......... 45
25 Electric analog model of Area B with no dams in the borrow canals
for L-30, L-31, and L-33 ............................................................................................ 48
26 Theoretical relations, from Manning's formula, between hydraulic
gradient, discharge, and depth for a canal 125 feet wide of rectangular
and trapezoidal cross section .............................. .................................................. 50
27 Electric analog model of Area B with control dams that isolate the
borrow canals for L-30, L-31, and L-33 from the intake side of the pumps ........ 54

TABLES

Table Page
1 Proposed discharge capacity of Area B pump stations ...................................... 10
2 Landfill requirements and elevations FHA requirements .................................... 11
3 Time-regressive rainfall comparison for hurricane years 1947 and 1960 ................ 14
4 Comparison of annual-mean discharges in the Miami Canal at N.W.
36th Street with the 24-year median, 1940-63 .......................................................... 34
5 Key to letter designations in Figure 19 for recording stage and dis-
charge gaging stations in canals in the Miami area ........................................ 37
6 Underseepage for the boundary condition of no control dams in the
levee borrow canals ...................................................... ....................................... 53

HYDROLOGIC EFFECTS OF AREA B FLOOD
CONTROL PLAN ON URBANIZATION OF
DADE COUNTY, FLORIDA
By
F. A. Kohout and J. H. Hartwell

ABSTRACT
Swampy low land (Area B) that fringes the Everglades west of
Metropolitan Miami, Florida (Area A) probably will be urbanized in
the future. Area B will be protected from flooding by huge pumps that
will pump water westward from Area B over a levee system into Con-
servation Area 3B. The total capacity of the pumps will be about 13,400
cubic feet per second which is sufficient to lower water levels 2 inches
per day in the 203 square miles of Area B. As this capacity is about equal
to the highest gravity-flow discharge to the ocean through existing canals
of the Miami area, a great potential will exist, not only for control of
floods, but also for beneficial control and management of a major segment
of the water resources in southeastern Florida.
An evaluation of flow in the Miami River during a low-water period
indicates that Conservation Area 3B contributes 33 percent of the total
discharge, Area B 26 percent, and Area A 41 percent. After implementa-
tion of the Area B plan, contributions from Area A will continue to flow
seaward, whereas contributions from Area B and Conservation Area 3B,
which now unavoidably are wasted to the ocean in a high-water period
will be pumped westward into storage in the conservation area.
A steady-state electric-analog study was made for the 1961 Area B
plan. Maps- e results showed that the water-level pattern would be
radically changed if water-control dams were installed to isolate the levee
borrow canal from the intakes ot te pump stations. out e con -
dams, the lowest steady-stateateter levels would occur at the western
side of Area B and underseepage from Conservation Area 3B would be
maximum. However, if dams were installed, the highest water levels
would occur at the western side of Area B and underseepage would be
minimized. Partial openings of the control dams probably would produce
advantageous compromise solutions between the two-modeled extremes.
Estimates of population growth indicate that water use in the Miami
area may amount to 1.4 billion gallons per day in 1995. This water use is
equivalent to 2,170 cfs (cubic feet per second), almost twice the yearly
mean discharge of 1,280 cfs that flowed into the ocean from six major
Miami area canals during the dry period June 1962 to May 1963. A rate

FLORIDA GEOLOGICAL SURVEY

of 1.4 bgd for a year's time is equivalent to the total surface runoff
(about 10.5 inches of water) from an area extending 28 miles westward
from the coast and 100 miles southward from Lake Okeechobee into
Everglades National Park. As other coastal cities and Everglades National
Park will require a share of water from this same area, improved water-
management techniques are needed to insure a continuing supply of fresh
water for southeastern Florida. In consideration of continually growing
water needs, the Area B plan should be conceived as a water conservation
as well as a flood control plan.

INTRODUCTION
In the near future, Miami and its surrounding communities are ex-
pected to grow far beyond their present limits. to the present time
Miami's development has been restricted largely to a broad ridge of hiigh
and called the Atlantic CoastaLdRige, figure 1, because of the relative
safety of this hih land from flooding. Standing only 8 to 15 feet above
mean sea level, the ridge is high only by Florida standards. Nevertheless,
it has been of paramount importance to development of communities
along the eastern coast of Florida, and were it not for the presence of
the ridge, Miami probably would not be what it is today. In contrast, the
area inland from the ridge has not been developed simply because it is
low and subject to perennial flooding. At this time, however, the coastal
ridge is largely developed and much of the future expansion of the urban
areas will have to be in the lowlands west of the ridge.
Theprotection from flooding in these lowlands is a difficult problem,
but agencies and land developers are making studies and devising plans
permit urbanization f h ln lands. The possible influence of these
_pl.n on thef Ftre water r0s4oc-f thi Mi m ra is the subject of
this report.
The basic problem is how to make this lowland area safe from floods-
or atTeast as safe as possible with techniques, construction methods, and
conc of hydrology now available to the planners. The technical
hydrologic problem is whether the proposed plans will accomplish t~eir
hydirologicaims to the satisfaction of all agencies involved and the citizens
-whail inhabitth area
Many agencies and their offices are involved. These include: Officials
of the City of Miami and Dade County, who have the civil responsibility
for the protection of residents living within their boundaries; the U.S.
Corps of Engineers, which is concerned with the planning and construc-
tion of protective facilities; the Central and Southern Florida Flood

FLORIDA GEOLOGICAL SURVEY

of 1.4 bgd for a year's time is equivalent to the total surface runoff
(about 10.5 inches of water) from an area extending 28 miles westward
from the coast and 100 miles southward from Lake Okeechobee into
Everglades National Park. As other coastal cities and Everglades National
Park will require a share of water from this same area, improved water-
management techniques are needed to insure a continuing supply of fresh
water for southeastern Florida. In consideration of continually growing
water needs, the Area B plan should be conceived as a water conservation
as well as a flood control plan.

INTRODUCTION
In the near future, Miami and its surrounding communities are ex-
pected to grow far beyond their present limits. to the present time
Miami's development has been restricted largely to a broad ridge of hiigh
and called the Atlantic CoastaLdRige, figure 1, because of the relative
safety of this hih land from flooding. Standing only 8 to 15 feet above
mean sea level, the ridge is high only by Florida standards. Nevertheless,
it has been of paramount importance to development of communities
along the eastern coast of Florida, and were it not for the presence of
the ridge, Miami probably would not be what it is today. In contrast, the
area inland from the ridge has not been developed simply because it is
low and subject to perennial flooding. At this time, however, the coastal
ridge is largely developed and much of the future expansion of the urban
areas will have to be in the lowlands west of the ridge.
Theprotection from flooding in these lowlands is a difficult problem,
but agencies and land developers are making studies and devising plans
permit urbanization f h ln lands. The possible influence of these
_pl.n on thef Ftre water r0s4oc-f thi Mi m ra is the subject of
this report.
The basic problem is how to make this lowland area safe from floods-
or atTeast as safe as possible with techniques, construction methods, and
conc of hydrology now available to the planners. The technical
hydrologic problem is whether the proposed plans will accomplish t~eir
hydirologicaims to the satisfaction of all agencies involved and the citizens
-whail inhabitth area
Many agencies and their offices are involved. These include: Officials
of the City of Miami and Dade County, who have the civil responsibility
for the protection of residents living within their boundaries; the U.S.
Corps of Engineers, which is concerned with the planning and construc-
tion of protective facilities; the Central and Southern Florida Flood

REPORT OF INVESTIGATIONS No. 47

I 4$ MIAMIr

co vCi o

-/ 0
00

0 10 20 30 O 4p \
MILES A1 ^ '

Figure 1. Physiographic provinces in southern Florida.
Control District (C&SFFCD), which has the responsibility for operating
the facilities built by the Corps of Engineers; and the Federal Housing
Authority which has the authority to underwrite much of the money that
will be used to build private dwellings in the lowland area. Because of
the concern of the Federal Housing Authority the basic question should

FLORIDA GEOLOGICAL SURVEY

perhaps be restated-will the present plans make the lowland area suffi-
ciently safe from flooding to be a good financial risk for banks and other
lending institutions and for the Federal Housing Authority to guarantee
the housing loans? In other words, will water-control facilities con-
structed on the basis of the present plan give sufficient assurance of
protection from flood waters so that residents may get long range credit
at reasonable cost on their investments in the lowland area?
The Corps of Engineers and the Central and Southern Florida Flood
Control District have devised a plan known as the Area B Flood Control
Plan to make the lowland area suitable for housing development. The
plan calls for an integrated system of land fills, drainage canals, and
large capacity pumps to control the flood hazard. It also would be part
of the overall flood-control plan for southeastern Florida. Before describ-
ing the Area B plan further a brief review of the overall hydrologic
situation in southern Florida and the overall flood-control plan seems to
he pertinent.

GENERAL HYDROLOGIC SITUATION AND OVERALL
FLOOD-CONTROL PLAN
The outstanding features of southern Florida which bear on the flood
hazard are moderately high preciitation low land-surface altitude and
relief, highly permeable soils and rocks and presence of the sea.
result mainly from short periods of heavy rainfall in rainy years,
but the floods do not necessarily coincide with years of greatest annual
rainfall. Factors that lead up to flood conditions include a havy hlildup
fTraiiiall over several months during which the drainage system has
sufficient time tonormalize after levels; this followed by intense rain-
fall usually associated with a hurricane. A companion problem is main-
t ing sufficiently high fresh-water levels and runoff to keep salt-water
encroachment at a minimum. The relief of the land is so low that during
periods of draught and high tides, particularly those associated with
storms, the sea may have a higher head than fresh water and as a result
salt water invades inland along waterways and contaminates both surface
and ground-water supplies. Thus the concepts that are applied must
both minimize flood hazards anhold ack the s water.
The original drainage system of the area from Lake Okeechobee to
the south and east coasts was incapable of preventing flooding in the
hurricane years of 1947 and 1948. It had to be improved to permit farm-
ing and cities to prosper. A plan called the Central and Southern Florida

REPORT OF INVESTIGATIONS No. 47 5

Flood Control Project was formulated by the Congress of the United
States and the State of Florida.
The overall flood-control plan is designed to protect the developed,
and potentially developable, urban, industrial and agricultural land on
the east, south, and west sides of Lake Okeechobee. Forplanning pur-
poses this region has been divided into three types of areas-agricultural,
conservation, and urban-industrial, shown in figure 2. Everglades Na-

Figure 2. Canal and levee system of the Central and Southern Florida Flood Control
project, in southeastern Florida.

FLORIDA GEOLOGICAL SURVEY

tional Park is under development by the U.S. National Park Service for
recreational purposes. The agricultural areas fringe the southern part
of Lake Okeechobee, and the urban areas are along the coast; between
them lie the conservation areas which are perennially flooded lands used
for storing water. The agricultural and urban areas are not flooded as
frequently as the conservation areas, because they are on slightly higher
ground than the lowlands. However, the ground is not so high that it
is not subject to floods occasionally, and it must be protected by levees
and drainage canals. After eacht ni atersrained as rapidly
as possible by a systeniof canals and pumping stations.
Conservation Areas 1, 2, 3A, zic 3arearge enough to accept excess
flood waters pumped from agricultural and urban areas. In plan, this
stored water will be available for release during dry seasons to help keep
high water levels in the canals and adjacent lands. These water levels
must be kept high enough during the dry season-first, to prevent
oxidation and burning of black muck agricultural soils, and second, to
prevent the encroachment of salt water in the canals and through the
rock in coastal areas. The flow in the canals is provided by drainage
from ground water in storage adjacent to the canals and by gravity
drainage and pumping stations which supply water from the conserva-
tion areas to the agricultural and coastal areas. In the agricultural areas
south of Lake Okeechobee, individual farmers pump water from diked
fields into the primary canal system; the large pumps, figures 3 and 4,
of the flood control system, in turn pump the water southward to the
conservation areas or northward to Lake Okeechobee. Some of the
pumping stations pump as much as 5,000 cfs, the equivalent of the flow
of many small rivers (for example as a comparison, the largest flow under
flood conditions in the Miami River at Hialeah in October 1947 was only
4,060 cfs (cubic feet per second)). The encroachment of salt water is
also in part contained by salinity-control dams and locks near the coast
which minimize the escape of fresh water to the sea and prevent the
movement of salt water up the canals at times of low flows.

AREA B PLAN

Where does Area B fit into this overall picture? It is part of the land
set aside for urban-industrial development but its use was held back
because of construction problems presented by flood hazards. Area B
is the lowland between the ridge occupied by Miami, designated as
Area A, and the lowland storage reservoir designated as Conservation
Area 3-B, shown in figures 2 and 5. Area B includes about 203 square

REPORT OF INVESTIGATIONS No. 47

, Y p\

Figure 3. Intake of pumping stations S-7 which has a capacity of 2,490 cubic feet per
second under design conditions.

Figure 4. One of the 131%-inch impellers at pump station S-7.

L.

c'

:c..--.

FLORIDA GEOLOGICAL SURVEY

4 EXPLANATION
3 .. -- Tronsmisslbllity, in million
Sallos 901 per day per foo)
/ T oGS: U.S. Geologlcol Survey
) /C Tran s iibii ty CE: U.S. Corps of Engnner
aS. 4 C~ &\ '1 "

Coanol and number
S\Control dom
Pump station and number
0 2 miles

Figure 5. Major features of existing and proposed canal and levee system in tile Miami
area.
miles. It is drained by canals which carry water from the conservation
areas through Miami to the sea. In its barest form, the Area B plan calls
for building up the land-surface elevation by rock-fill dug from canals.
The canals would serve as conduits for dewatering Area B during the

REPORT OF INVESTIGATIONS No. 47

rainy season by pumping the water westward into conservation area 3-B,
and by gravity drainage toward the sea through Area A. Flood water
from Area B, once it was in the conservation area, would be handled as
part of the water resources of the overall plan for flood control and
drainage in southeastern Florida. The plan calls for filling about 45
percent of Area B to an elevation of 5 feet above msl and 40 percent to
an elevation of 4 feet above msl (mean sea level). The balance of 15
percent would be in canals and borrow lagoons.
The problem with which this report is concerned then is this: From
a consideration of hydrologic factors of flooding, drainage and salt-water
encroachment is the Area B plan adequate to provide the protection
needed for its development?
Additionally, water control in Area B will strongly influence the
future water resources of the Miami area generally, and as a partial
evaluation of this influence, the following main topics are considered in
this report:
1. Operation of the Area B plan as proposed in 1961.
2. Future water requirements of the Miami area.
3. A summary of past hydrologic extremes in the Miami area and
effects on the hydrology caused by works of the Central and
Southern Florida Flood Control Project that were in operation
prior to 1962.
4. The results of steady-state electrical analog studies of the Area
B plan.
The evaluation of the Area B plan contained in these pages was made
at the request of the Central and Southern Florida Flood Control District
(C&SFFCD). General supervision was provided by C. S. Conover, Talla-
hassee, District Chief of the Water Resources Division, U.S. Geological
Survey.

DETAILS OF THE AREA B PLAN
Detailed description of the Area B plan is given in the survey review
report by the U.S. Army Corps of Engineers (1961). Major constructional
features of the plan are shown in figure 5. Four pump stations S-200 to
S-203 will discharge water westward into Conservation Area 3B at the
rates shown in table 1. The design pumping heads would vary from 8.1
to 8.7 feet for the four stations.
Existing pump station S-9 (fig. 5) has a capacity of about 2,900 cfs;
its discharge is directed westward into Conservation Area 3A through
the borrow canal of Levee 67 (fig. 2). Existing large canals in 1964 are

FLORIDA GEOLOGICAL SURVEY

TABLE 1.-PROPOSED DISCHARGE CAPACITY OF AREA B
PUMP STATIONS.
(U. S. CORPS OF ENGINEERS, 1961, p. A-11 AND A-16).

Drlsign lrada
i'umnpilng Numlnbr (ft aliove n11*1) Unit cnipcity Total capacity
.1tit n of unit. in cls inl cfs
Intake Disclharg
-2lo 3 3.0 11.1 980 2.940
S-201 3 3.0 11.1 870 2,610
5 202 4 3.0 11.5 980 3.920
.2t:1 .t 3.0 11.7 9810 1.920

shown in figure 5. New large primary canals referred to as "feeder canals"
by the Corps of Engineers are proposed to deliver water to stations S-202
and S-203. Because of anticipated high seepage of water eastward from
Conservation Area 3B through permeable limestone underlying Levees
:30 and 33, seepage-reduction levees will be constructed approximately
3,000 feet westward from the existing levees (fig. 5). The seepage-
reduction levees are flared near the pump outlet to permit the discharged
water to spread more rapidly into the conservation area. Borrow canals
located on the westward side of the seepage-reduction levees will aid
in transmitting the water away from the pump stations.
The water level in Conservation Area 3B during flood conditions is
expected to be about 11 feet above msl; the maximum observed head
on the discharge side of S-9 during pumping was 11.62 feet on October
13, 1963. The pump discharge capacities in Table 1 are based on design
water levels of 3 feet above msl at the intake side of each pumping
station and 11.1 to 11.7 feet at the discharge side. Electrical analog
studies presented later tend to indicate that because of the water-level
gradient required to move water through the major feeder canals, an
intake water level ranging from msl to 1 foot above msl may be more
realistic under full capacity pumping. The pumping capacity for all
pumps is designed to remove about 2 inches of water per day from the
203 square miles of Area B.
Table 2, which gives proposed land-fill requirements, is quoted from
the U.S. Corps of Engineers Survey Review Report (1961, table 6,
page 16):
The survey review report gives the following percentage breakdown
for final land-surface elevations: "For the average size subdivision lot in
a typical new development block, this would amount to 15 percent of the
area being devoted to canals and borrow lagoons, 45 percent filled to
elevation 5 feet on the average, and 40 percent to elevation 4 feet."

REPORT OF INVESTIGATIONS No. 47

TABLE 2.-LAND-FILL REQUIREMENTS AND ELEVATIONS-
FIIA REQUIREMENTS.

Minimum flood As.-umedl e irrpondilni;
Portion of nrne frcquenoy fill elevation
(yolr) (ft)
Above 5.0. floor
Elevation of finish ground lIne (all dwellilngs) ............ ............. I in 50 rlvel 6.0
Crown of .tlrr't ......., .. ............ ............. .......... 1 In n 5,0
2-1-lr. drainage.
Strcots, swnle or ditches.... ................... ..... ... ...n f nllowllg 1 il. 4.0
10 yrtFr ltuor
Fronll. side. aind required 15.foot u riblo rnar y)tlud ,................. 1 i 10 5.0
livnltinder (mostly further lack ynrds) ......................................... .0

The design rainfall for the Area B plan is 12.79 inches on the first
day and a total of 17.22 inches for 5 days. Prior to this storm the water
level for Area B is assumed to be --3 ft. msl. Under the specifications
of Table 2 and the previous quotation and taking account of the storage
space available as surface water (100 percent storage coefficient) and as
ground water (17 percent storage coefficient, assumed), the water level
after the first day of the design storm is calculated at +5 ft. msl (U.S.
Corps of Engineers, 1961, table 6). The plan visualizes lowering water
levels from elevation 5 feet to 4 feet by the end of the fifth day with 2
inches per day being removed by pumpage to the west and one inch
per day being removed by gravity drainage to the ocean through Area
A canals.

RAINFALL INTENSITY RELATED TO FLOODING

Rainfall averages 59 inches per year, three-quarters of which falls in
1 e-"-n
the Mlay tn nvember ramy season.
f primary concern are the periods of heavy rainfall that produce
oding. Maximum flood ama e occurred in 1947 and -, and ex-
esiveflooding occurred in 1960. The following comarison shows
intensity and distribution of rainfall during theyeaian impoant
factor in producing flood conditions. The annual rainfall in 1959 ex-
ceeded tIat of 194 Tand 1960 by about 10 and 20 inches, respectively,
shown in figure 6. In contrast, flooding was minimal in 1959 compared
to the other years, in spite of the fact that many low-lying areas were
urbanized by 1959. ors le o flood co
heavy buildup of rainfall over several months during which the drainage
-sytem has insufficient time to normalize water levels, and 2) this buildup
followed by intense rainfall, usually associated with a hurricane.

FLORIDA GEOLOGICAL SURVEY

MIAMI WEATHER
BUREAU (AIRPORT)

HIALEAH
WEATHER STATION

Figure 6. Accumulation of rainfall in 1947, 1959, and 1960.

The passage of Hurricane Donna and two weeks later tropical storm
Florence in September 1960 produced the highest single month rainfall
in recent times. The isohyetal map of figure 7, adapted from an unpub-
lished report of the C&SFFCD, shows that rainfall over Area B ranged
from less than 16 inches in the northwest corner to greater than 28
inches in the southeast corner.
Improvements in the drainage system between 1947 and 1960 result
in more rapid lowering of water levels between rains. A time-regressive
comparison of rainfall for the two years indirectly indicates the effect
of these improvements. The average of all stations (Table 3) shows that
the rainfall in 1960 slightly exceeded that of 1947 for three months
(including the highest month) before maximum flood conditions. In
contrast, the high-water maps (p. 28 and 29) show that maximum water
levels in Area B were about 3 feet lower in 1960 than in 1947. As ante-
cedent rainfall for the two years is comparable, the relatively lower

REPORT OF INVESTIGATIONS No. 47

Figure 7. Rainfall for September 1960 following the passage of Hurricane Donna and
tropical storm Florence in tie Miami area.

maximum water level in 1960 undoubtedly relates to improvement of
the flood-control system between 1947 and 1960.

TABLE 3.-TIME.REGRESSIVE RAINFALL COMPARISON FOR HURRICANE YEARS 1947 AND 1960

Accumulated rainfall antecedent to and including the maximum month

Location

Fort Laudcrdale

Hialeah
Homestead

Kendall

Miami Airport
Miami Beach

Pennsuco
Pennsuco 4 NW

Tamiami Canal
Tamiami Trail
C 40-Mile Bend
Average of all stations

4 months

1987 1960

59.75
43.38

52.02

30.40
45.62
37.05
40.98

38.42

47.13

48.89

44.36

36.77
37.17

55.95
44.12
40.13
30.81

35.32

37.93
48.74

50.46
41.74

3 months 2 mnnthll

46.10

33.54
38.40

19.11

32.11
30.40

30.37
30.43

36.56

36.33

33.34

29,19

32,01

42,43
37,56

33.82
27.38

29.00

30.28

40.20

41.60

33.35

37.25

28.59
26.33

13.14

25.45
21.48
24.62

23.35

29.50

29.98
26.47

23.59

28.02
28.53
32.87

28.55

21.08

22.25
23.45

31.93

28.94
26.92

Maximum month

Oct. Sept.
1917 1960

21,55

17.73

15.96

6.83
14.85

15.18

16.29
14.74

18.96

18.42
16.04

16.07

20.48
19.04

27.84
21.40
16.02

16.31
17.97

22.36

19.05

19.95

Annual

102.36

78.25

91.07
67.10
78.39

67.50
72.28

70.39

76.38

82.76
78.95

1960

60.48

68.81
82.12

69.93

70.26

55.67 W
62.53

66.37

76.14

73.91
68.62

--.7 r

--------Ll I ---

I I I 1 I -

---

REPORT OF INVESTIGATIONS No. 47

QUANTITATIVE ESTIMATES OF PREVIOUS INVESTIGATIONS
The U. S. Corps of Engineers (1953) performed 11 pumping tests
to determine the permeability of materials underlying various, parts of
southern Florida. Based on several of these tests the range of under-
seepage beneath Levees 30 and 33 was computed at 1,380 to 1,600 cfs
per mile of levee for a 10-foot head differential. Stallman (1956) described
the effects on the water resources of the area and, based on analog and
numerical-analysis studies, estimated the underseepage at 970 cfs per
mile of levee for a 10-foot head differential under laminar flow condi-
tions in a homogeneous aquifer. Based on measured pickup in a one-mile
reach of the L-30 borrow canal near S-201 (fig. 5), Klein and Sherwood
(1961) computed underseepage at 540 cfs per mile for a 10-foot head
differential between the ponded conservation area and the borrow canal.
The U. S. Corps of Engineers (1961, p. 17) estimated that total under-
seepage would amount to 3,300 cfs, under a 6-foot head differential
(11-5 ft) after occurrence of the design storm. Dividing this discharge
figure by 24 miles (the approximate length of levee bordering Area B),
the estimated underseepage would be about 140 cfs per mile. With the
addition of the seepage-reduction levees the estimated underseepage
would be 2,400 cfs or about 100 cfs per mile. Thus, the estimated under-
seepage has been revised downward from a maximum of 1,600 cfs per
mile to. a minimum of 100 cfs per mile based on additional studies and
changes in the flood-control plan. Calculations to be presented later for
conditions that appear representative indicate that the underseepage
will be somewhat higher than the minimum estimate of 100 cfs per mile.
Water requirements for preventing salt-water encroachment during
the diy season have received consideration in several reports. Based on
measurements of canal discharge, Sherwood and Leach (1962) estimated
that during extreme drought 50 cfs would be needed to maintain a water
level of 2.75 feet above msl at the control dam in the Snapper Creek
Canal (C-2, fig. 5). Outseepage from the canal into the aquifer near
the coastline is a necessary part of preventing salt-water encroachment
into the aquifer at depth. Leach and Sherwood (1963) in a similar
study for the Snake Creek Canal (C-9, fig. 5) estimated that 36 cfs would
be required to maintain a water level of 2.7 feet above msl at the control
dam in that canal. These estimates were based on measured canal
discharges. A water level of 2.5 feet will prevent salt-water encroach-
ment in the Biscayne aquifer. Assuming that an average of 40 cfs per
canal would be required to maintain a water level of 2.5 feet above msl,
a total of about 300 cfs would adequately maintain heads at the coastal
control dams in the eight major canals of Dade County.

F'L0o1DA GEOLOGICAL SUuRNTY

ACKNOWLEDGMENTS
Thanks arc extended to William V. Storch and Robert L. Taylor of
the Central and Southern Florida Flood Control District and F. D. R.
Park and Marvin J. Brooks of the Dade County Water Control office
for discussions related to this report. The writers' colleagues A. L. Higer,
Howard Klein, C. B. Sherwood, and S. D. Leach provided helpful counsel
during the investigation. The manuscript received the benefit of critical
review by C. S. Conover, R. W. Pride, K. A. MacKichan, C. A. Appel,
and Leo A. Ileindl.

FUTURE WATER NEEDS AND AVAILABILITY
Although the primary function of the Area B plan would be flood
control, its implementation also would result in conservation of water.
Calculations are made in this section to demonstrate the magnitude of
future water needs vs. availability and to point out the importance of the
Area B plan as a water-conservation measure.
In figure S, estimates for water use by the Dade County Development
Department (1962, sec. 30, p. 15-16) are plotted to the year 1995.
Agricultural pumpage is expected to decline because of urbanization
but industrial and municipal pumpage will rise greatly. Per capital daily
water use is expected to increase from about 145 gallons in 1960 to 220
gallons in 1995. The rise in population from about 1,000,000 in 1960 to
4,0(X).H0) in 1995 will cause total water use to increase from about 230
mgd ( million gallons per (lay) (345 efs) to about 1.4 bgd (billion gallons
per day) (2,170 cfs).
Approximating the annual rainfall at 60 inches (a depth of 5 feet),
the total water use of 1.4 bgd for a year is equivalent to the total rainfall
over an area of about 500 square miles. As a comparison, the mainland
area south of the Dade-Broward County line in the map of figure 5
amounts to about 500 square miles. However, as the total rainfall is
not available for use, water will have to be imported from adjacent
areas to supply the populace of 1995.
The following equation represents the balance between recharge by
rainfall, discharge, and water storage in a drainage area:
Recharge [rainfall] = Discharge [surface-water discharge + ground
water discharge + evapotranspiration + domestic pumpage] +
[+ change in storage.]
For purposes of discussion, several elements in the equation can be
eliminated from consideration because they are not likely to change
in the future:

REPORT OF INVESTIGATIONS No. 47

YEAR
1930 1940 1950 1960 1970 1980 1990 2000
10,000 L 10,000

S-
0
x /

o 0

10 100
a-
0 0

a-t

10 --~ --/- -- -- 10

Figure 8. Estimated water use per day between. the years 1930 and 1995 for Dade
County and the Florida Keys.

I. Rainfall cannot be expected to change significantly in the future.
2. Due to the nature of ground-water movement and the necessity
for maintaining fresh-water heads to prevent salt-water encroach-
ment, ground-water discharge cannot be changed greatly from
its present magnitude.
3. Evapotranspiration is occurring now and will occur in the future
at about the same rate; i.e. the future water problems of the
Miami area probably will be solved by storing water in the con-
servation areas; only under very adverse conditions during drought

FLORIDA GEOLOGICAL SURVEY

would water levels be lowered sufficiently below ground surface
to reduce evapotranspirative losses.
4. Long-term storage in the Miami area (i.e. average water levels)
are not expected to change significantly and this parameter will
average out to zero in the future.
In the above recharge-discharge equation only domestic pumpage
and surface rnnoff can be considered as changeable. As domestic pump-
age will increase six-fold, the most readily available method for main-
taining the balance of the system is by prudent management of surface
waters: by reducing surface-water discharge to the ocean and/or by
increasing surface-water inflow to the Miami area.
A volumetric computation that balances the domestic pumpage of
1995 against surface rnnoff is instructive. Langbein (Parker, et al., 1955,
fig. 149) found that surface-water discharge from the Everglades Unit
averaged 9.54 inches during the years 1940-46 when precipitation aver-
aged 50.1 inches. Thus, 19 percent of precipitation could be assigned
to surface runoff.
The average annual precipitation for the Everglades and Southeastern
Coast as determined by the U. S. Weather Bureau is about 55 inches.
Using Langbein's percentage, 10.5 inches of this would represent average
surface-water discharge. If the total water use of 1.4 billion gallons
per day in 1995 were derived entirely by diversion of average surface-
water flow to the Miami well fields, consider the area over which pre-
viously excess surface runoff would have to be collected.
(Annual surface-water discharge) X (Area) = Annual pumpage
(10.5 inches/yr) X (Area) = 1.4 X 10 gal/day X 365 days/yr
12 inches/ft 7.48 gal/cu. ft.
Area = 7.85 X 1010 sq. ft. = 2,820 sq. miles.
Such an area (about 28 miles wide and 100 miles long) would
extend from the east coast to the southern end of L-67 and from the
middle of Lake Okeechobee on the north into Everglades National Park
on the south. (See fig. 2.) All of the annual surface runoff (10.5 inches)
would have to be collected from this large area so that Miami might
use the water once and then dump it in the ocean. On this basis there
would he no surface runoff left, above the needs of Miami, to supply
replenishment water for West Palm Beach, Fort Lauderdale, and other
coastal cities, or Everglades National Park. Because water is a reuseable
resource, the situation will not be as bleak as indicated by this volumetric
computation. However, it is clear that the various factors in the hydrologic
cycle must be studied carefully so that enlightened water management
can insure a continuing supply of fresh water for southeastern Florida.

REPORT OF INVESTIGATIONS No. 47

In the above computation a tacit assumption was made- that all
surface runoff would be funneled to Miami and after consumption by
the populace, the water would be processed by municipal-sewage plants
and thence dumped into the ocean. This would represent a total dissi-
pation, i.e. total consumption of fresh water which is not occurring at
the present time. Of about 1,000,000 total population in 1960, sewage-
treatment plants served about 420,000; the effluent from a population
of only 250,000 was pumped directly to Biscayne Bay or to the Gulf
Stream (Dade County Development Dept., 1962, sec. 29, p. 5-13).
Therefore, in 1960 only one-fourth of the population was served by
sewage-treatment plants that dumped the effluent into the ocean; the
remaining three-fourths were served by sewage-treatment plants or by
individual septic tanks that discharged the effluent into fresh-water
canals or into the Biscayne aquifer. The following quotation gives back-
ground on the present status of sewage disposal (Dade County Develop-
ment Dept., 1962, sec. 29, p. 1-2):
"Shortly after World War II a local Miami firebrand named
Philip Wylie (creator of Crunch and Des) authored an article in a
national magazine calling Miami a 'Polluted Paradise.'
"Little could be said against the author's contentions for Miami
had reached a shocking state in pollution of its formerly-blue
Biscayne Bay.
"For then the waters were turgid brown and even the twice-daily
flushing action of ocean tides could hardly save marine life from
extinction in the central bay area or dilute the bacteria-laden waters
that poured out of the mouth of the Miami River.
"All the raw, untreated sanitary sewage of the complete down-
town area was merely collected through mains and then poured
into the river and bay through open outfalls.
"Outright warnings by health authorities and incessant campaigns
by Miami newspapers, finally aroused the citizenry and major action
was taken.
"Today, the downtown area of Biscayne Bay has noticeably
changed color as years of sanitary sedimentation washed away by
the never ceasing tides.
"Also, the City of Miami, for its major downtown and bayfront
areas, is serviced by a complete collection and treatment facility
which discharges a clear effluent far offshore into the world's largest
moving body of water- the Gulf Stream. At present, much of the
inland residential areas are unsewered."

FLORIDA GEOLOGICAL SURVEY

Because sea water contains 35 times as much dissolved solids as,
sewage, it is much cheaper to purify and sanitize sewage water than to
remove the salts from sea water (Wolman, 1961, p. 123). Therefore, it
is doubtful that salt-water conversion plants will ever be economically
justified in a high-rainfall region such as Miami. However, all surface-
water outflow from southeastern Florida cannot be stopped and funneled
to Miami as conjectured by the previous computation. In the year 1995
(or eventually) it appears that some planned reuse of water will be
essential if water shortages are to be avoided. Possibly half of the 1.4
billion gallons per day of water that will be required in 1995 (or
eventually) could be saved for reuse by adequately planned sewage-
treatment systems. In flood-prone areas, such as Area B, the septic-tank
system would not be workable and municipal sewage-treatment plants
would be required. However, consideration should be given to planned
reuse of the water by recharging highly purified sewage-plant effluent
into Area B canals. Subsequent discharge into Conservation Area 3B
through the flood-control pumps would permit time for bacterial de-
gradation and for the benefits of aquifer filtration to make the water
aesthetically reusable. In consideration of the magnitude of future water
needs, the Area B plan should be conceived as a water-conservation
as well as a flood-control plan.

GEOLOGIC AND HYDROLOGIC ENVIRONMENT
Although the levee system prevents surface-water outflow from Con-
servation Area 3B, underseepage and direct rainfall overpower the present
gravity drainage system, figure 9, and the land in Area B remains swampy
or partly inundated during much of the year. Figure 9 shows both
primary and secondary canals, but the secondary canals will be omitted
henceforth. Unusual shapes of water-level contours in later illustrations
will be clarified by referring to the complete drainage system in figure 9.
The Biscayne aquifer is an important hydrologic unit that underlies
southeastern Florida. It is a highly permeable water-table aquifer
consisting of solution-riddled limestone and calcareous sandstone and
fairly numerous layers of unconsolidated sand. Municipal and private
water supplies are derived almost exclusively from wells drilled into
the aquifer. The aquifer thickens toward the coast from about 50 feet
at the levee system on the west side of Area B to 90 feet on the east
side, and to as much as 200 feet near the coast. Oolitic limestone crops
out over much of the coastal ridge (Area A). In Area B, a surficial blanket
of peat and organic marl 3 to 4 feet thick is underlain by dense low-
permeability limestone having a thickness of about 3 feet. Highly
.1

F'L0o1DA GEOLOGICAL SUuRNTY

ACKNOWLEDGMENTS
Thanks arc extended to William V. Storch and Robert L. Taylor of
the Central and Southern Florida Flood Control District and F. D. R.
Park and Marvin J. Brooks of the Dade County Water Control office
for discussions related to this report. The writers' colleagues A. L. Higer,
Howard Klein, C. B. Sherwood, and S. D. Leach provided helpful counsel
during the investigation. The manuscript received the benefit of critical
review by C. S. Conover, R. W. Pride, K. A. MacKichan, C. A. Appel,
and Leo A. Ileindl.

FUTURE WATER NEEDS AND AVAILABILITY
Although the primary function of the Area B plan would be flood
control, its implementation also would result in conservation of water.
Calculations are made in this section to demonstrate the magnitude of
future water needs vs. availability and to point out the importance of the
Area B plan as a water-conservation measure.
In figure S, estimates for water use by the Dade County Development
Department (1962, sec. 30, p. 15-16) are plotted to the year 1995.
Agricultural pumpage is expected to decline because of urbanization
but industrial and municipal pumpage will rise greatly. Per capital daily
water use is expected to increase from about 145 gallons in 1960 to 220
gallons in 1995. The rise in population from about 1,000,000 in 1960 to
4,0(X).H0) in 1995 will cause total water use to increase from about 230
mgd ( million gallons per (lay) (345 efs) to about 1.4 bgd (billion gallons
per day) (2,170 cfs).
Approximating the annual rainfall at 60 inches (a depth of 5 feet),
the total water use of 1.4 bgd for a year is equivalent to the total rainfall
over an area of about 500 square miles. As a comparison, the mainland
area south of the Dade-Broward County line in the map of figure 5
amounts to about 500 square miles. However, as the total rainfall is
not available for use, water will have to be imported from adjacent
areas to supply the populace of 1995.
The following equation represents the balance between recharge by
rainfall, discharge, and water storage in a drainage area:
Recharge [rainfall] = Discharge [surface-water discharge + ground
water discharge + evapotranspiration + domestic pumpage] +
[+ change in storage.]
For purposes of discussion, several elements in the equation can be
eliminated from consideration because they are not likely to change
in the future:

REPORT OF INVESTIGATIONS No. 47

XIL A IO

G 799-- / O

C.'C
-5 1 _/G ,,

~ G539 EXPLANATION
* *6553
Observation wes rated Obtorvolion wl t ind number
(_~p `b /oo Coaal and number
V^ n U ^f 0Control dom
_cir Pump slalion and number

\- I \ \ 0mlit

Figure 9. Primary and secondary canal system in 1964 and locations of recording
observation wells related to tie investigation, in tile Miamni area.

permeable limestone underlies this sequence from about -3 feet msl
to the base of the aquifer.

FLORIDA GEOLOGICAL SURVEY

PRESENT AND FUTURE LAND-SURFACE ALTITUDE

The ultimate altitude of land surface in Area B will be fixed by land-
fill requirements which will be based upon a compromise of hydraulic
and physical factors. The physical factors are outlined here.

'I

EXPLANATION
SContour nlterval, I tool.
Topogrphw Cntour Dotum is moen sea
level.

)C2
b -

Conol ond number
Control dam
Pump lotion and

0 2 4 nlle
siaa!!Ml

Figure 10. Generalized altitude of land surface in Area B.

REPORT OF INVESTIGATIONS No. 47

Peat, black-muck, and organic-marl soils occur at the surface over
most of Area B; the altitude of present land surface is given by the
generalized map of figure 10, compiled from maps of the U. S. Depart-

Figure 11. Altitude of bed rock in Area B.

FLORIDA GEOLOGICAL SURVEY

Because sea water contains 35 times as much dissolved solids as,
sewage, it is much cheaper to purify and sanitize sewage water than to
remove the salts from sea water (Wolman, 1961, p. 123). Therefore, it
is doubtful that salt-water conversion plants will ever be economically
justified in a high-rainfall region such as Miami. However, all surface-
water outflow from southeastern Florida cannot be stopped and funneled
to Miami as conjectured by the previous computation. In the year 1995
(or eventually) it appears that some planned reuse of water will be
essential if water shortages are to be avoided. Possibly half of the 1.4
billion gallons per day of water that will be required in 1995 (or
eventually) could be saved for reuse by adequately planned sewage-
treatment systems. In flood-prone areas, such as Area B, the septic-tank
system would not be workable and municipal sewage-treatment plants
would be required. However, consideration should be given to planned
reuse of the water by recharging highly purified sewage-plant effluent
into Area B canals. Subsequent discharge into Conservation Area 3B
through the flood-control pumps would permit time for bacterial de-
gradation and for the benefits of aquifer filtration to make the water
aesthetically reusable. In consideration of the magnitude of future water
needs, the Area B plan should be conceived as a water-conservation
as well as a flood-control plan.

GEOLOGIC AND HYDROLOGIC ENVIRONMENT
Although the levee system prevents surface-water outflow from Con-
servation Area 3B, underseepage and direct rainfall overpower the present
gravity drainage system, figure 9, and the land in Area B remains swampy
or partly inundated during much of the year. Figure 9 shows both
primary and secondary canals, but the secondary canals will be omitted
henceforth. Unusual shapes of water-level contours in later illustrations
will be clarified by referring to the complete drainage system in figure 9.
The Biscayne aquifer is an important hydrologic unit that underlies
southeastern Florida. It is a highly permeable water-table aquifer
consisting of solution-riddled limestone and calcareous sandstone and
fairly numerous layers of unconsolidated sand. Municipal and private
water supplies are derived almost exclusively from wells drilled into
the aquifer. The aquifer thickens toward the coast from about 50 feet
at the levee system on the west side of Area B to 90 feet on the east
side, and to as much as 200 feet near the coast. Oolitic limestone crops
out over much of the coastal ridge (Area A). In Area B, a surficial blanket
of peat and organic marl 3 to 4 feet thick is underlain by dense low-
permeability limestone having a thickness of about 3 feet. Highly
.1

FLORIDA GEOLOGICAL SURVEY

V
EXPLANATION
S Shows assumed allutude
of land surface after
STopog'ophic Contour CompoCtion. Conlour
interval, 0.5 ond I fool.
C/OO Datum is mean sea evI
S2 Conol and number
u0 -cf"- Control dam
&cdi Pump station and number

0o 2 4 mWtI

Figure 12. Assumed altitude of compacted land surface in Area B after 100 percent
loss of black-muck soils above +3 feet msl and 50 percent compaction of
muck soils below +3 feet msl.

ment of Agriculture, Central and Southern Florida Flood Control District,
and the U. S. Corps of Engineers. The altitude of the underlying bed-

REPORT OF INVESTIGATIONS No. 47

rock surface has been determined by the Corps of Engineers as shown
in figure 11.
Upon exposure to air after the Area B plan is operational, the organic
soils are expected to oxidize and the resulting soil loss is assumed at
100 percent from land surface to an altitude of +3 feet msl and 50
percent below 3 feet (Corps of Engineers, 1961, p. 16). The planned
water level in Area B is +3 feet msl. Below +3 feet msl integration of
organic soils with solid materials during land-filling will provide minimum
exposure to air and this is expected to reduce oxidative loss to 50 percent.
Based on the assumptions, a map of the compacted land surface has been
compiled, (see figure 12). The altitudes shown in this map would be the
base from which solid-material fill requirements could be estimated.

TRANSMISSIBILITY OF THE AQUIFER
The coefficient of transmissibility (T) is a measure of the ability of
the aquifer to transmit water. It is defined as the rate of flow of water
in gallons per day through a vertical strip of the aquifer one-foot wide
extending the full saturated height of the aquifer under a unit hydraulic
gradient (Ferris, et al., 1962, p. 73).
The coefficient of transmissibility has been determined at the sites
shown in figure 5. The Corps of Engineers performed a number of
determinations along Levees L-30 and L-33 in connection with Area B
under-seepage studies. These are identified by "C.E."; determinations
by the Geological Survey are identified "G.S." Near S-201 (fig. 5)
independent determinations by the two agencies by different methods
gave comparable results (Klein and Sherwood, 1961, p. 18). Although
the density of the determinations does not warrant contouring to portray
the areal variation, a region of high transmissibility occurs near Levees
30 and 31, along the western and southern boundaries of Area B. North-
ward and eastward the transmissibility decreases to about 4,000,000
gpd/ft near the eastern boundary of Area B.

EFFECT OF FLOOD CONTROL PROJECT ON
GROUND-WATER LEVEL
GROUND-WATER FLUCTUATIONS
The adjustment of ground-water levels to drainage activities and
water-control measures is shown in figure 13. The water-level peaks or
lows (i.e. points of water-level reversal) in recording wells S-18, G-10,
and G-72 have been selected to typify the range in fluctuation and are
plotted against annual rainfall (see locations fig. 9). The decrease in

FLORIDA GEOLOGICAL SURVEY

1940 1945 1950 1955 1960
MIAMI AIRPORT

10.--------------------

Figure 13. Monthly trend of water-level fluctuations in selected wells related to
rainfall, 1940-63.
amplitude of the envelope formed by connecting the yearly peaks is the
result of improvement of the drainage system over the years. For
example, the highest water level after the hurricanes of September 1960
is 2 to 3 feet lower than those of hurricane years 1947 and 1948 despite
equivalent rainfall conditions in 1960. The distribution of rainfall during
the year has been mentioned previously as a factor in flooding. Thus,
in well S-18 two individual water-level peaks at about 4 feet in 1959
correspond with two widely spaced heavy rains. Though total rainfall
in 1959 was greater than in 1960, the drainage system adequately lowered
or normalized water levels between the heavy rains so that the second
rainfall period produced minimal flooding in 1959.
In addition to improved ability of the flood-control works to lower
flood peaks, the generally rising line of the annual low-water minimum

REPORT OF INVESTIGATIONS NO. 47

in well S-18 indicates that progress is being made in controlling over
drainage and consequently in maintaining water levels at desirable levels.
However, the water level at S-18 fell to one foot above msl in May 1962.
This head is insufficient to prevent salt-water encroachment. In May
1962 Conservation Area 3B in the vicinity of well G-968 (fig. 9) was
dry. Ground-water level at G-968 was 2.0 feet above mean sea level,
only about 0.2 foot higher than that at well G-72 (fig. 13). Thus, after
four years of above average rainfall (1957-60) there was not enough
surface water stored in Conservation Area 3B to carry through the dry
year of 1961 and into 1962. This points up the need for water conserva-
tion. The problems of the future are not how fast the flood water can
be eliminated, but rather how the flood water can be saved for future
use. The Area B plan will be an instrument of water conservation.
After implementation, part of the water which now is wasted to the
ocean in a hurricane year such as 1960, will be pumped westward into
Conservation Area 3B.

COMPARISON OF HIGH-WATER PERIODS
The highest ground-water levels prior to inception of the Flood
Control Project occurred in 1947. These levels are duplicated on the
general base map of this report, figure 14 (adapted from Schroeder,
Klein, and Hoy, 1958, fig. 16). Water level over most of Area B was
9 to 10 feet above msl about 3 to 5 feet above land surface. Figure 15
shows the highest altitude of the water table in September 1960. The
increase in secondary-canal networks associated with urbanization of
Area A, and enlargement of the major canals improved total drainage
capability so that water levels in Area B ranged from 5 to 8 feet above
msl, 2 to 3 feet lower than those of 1947. The dense network of secondary
canals adjacent to the upper reaches of canals C-7 and C-8 reduced
water levels to 4 to 5 feet in 1960, compared to 7 to 8 feet in 1947. In
contrast, water levels in the vicinity of canals C-1 and C-100 in south
Dade County were slightly higher in 1960 than in 1947 which correlates
with relatively higher rainfall in 1960 (Kendall and Homestead stations,
table 3). Canal C-100 was not in existence in 1960 and C-1 has been
greatly improved since that time. It is unlikely that the high heads of
1960 in the south Dade region will ever occur again.

COMPARISON OF LOW-WATER PERIODS
Salinity-control dams were not installed in most of the canals until
1946. Lowest water levels of record occurred in May and June 1945,
figure 16 (adapted and expanded from Parker, et. al., 1955, fig. 45).

FLORIDA GEOLOGICAL SURVEY

EXPLANATION
Shows ot)itude of woer
Eob-- a. Conltour Inltrvol, I
Sbt'.Tab Cao.w fool. Datum is mean
Sseano el.
S Canal and number
1 1 1 C ntrol dom
E Pump olton and ber
SNot*: Adopled hom Sc.roda., etn and Hay. 19

Figure 14. HIigh-stage water levels in the Miami area October 11-12, 1947. Canal C-100
did not exist and C-1 was not improved in 1947.

The water table in Area B ranged from 0.5 to 1.5 feet above msl.
Localized mounds persisted in the more populated regions near the
shore and possibly give evidence of septic-tank recharge.

REPORT OF INVESTIGATIONS No. 47

Shows altitude of woter
--- toble. Dashed where appw
tw r-Tbb CTonr imale. Contour inlervl. 0.5
0 and I toot. Datum is mea
f C sea level.
~Canal and number
Q\ C Control dam
f0 ==N12= Pump station and number

0 2 4 milrls

Figure 15. Highest water-table altitude in the Miami area in September 1960 after
passage of Hurricane Donna and tropical storm Florence. Canal C-100 did
not exist and C-1 was not improved in 1960.

The lowest water levels of recent times occurred in May 1962 fol-
lowing drought conditions of 1961-62 (figure 17, adapted from Sher-
wood and Klein, 1963, fig. 9). The water table in Area B ranged from

FLORIDA GEOLOGICAL SURVEY

EXPLANATION
S-- .---'- Shows aolitude of water
-0.- table. Contour interval,
WO) W -ble cr-b i l 0.5 foot. Dolum is
C 0 o7o meon sea level.
C Conol and number
S Control dam
& u Pump station and number
Note: Adapted and expanded from Parker, et.ol.,
1955 2 4 mile

Figure 16. Record low stage of water table prior to installation of control dams in the
Miami area, May and June 1945. Canal C-100 did not exist and C-1 was
not improved in 1945.

1.0 to 2.5 feet above msl. No surface water was impounded in Con-
servation Area 3B at that time, but the major canals were draining
I

REPORT OF INVESTIGATIONS No. 47

c3

No

V
EXPLANATION
-o.5- Shows altitude of water
table. Contour interval,
W -To* Caer"" 0.5 foot. Datum is
mean sea level.
VVVV~1 Area of saltwater encrnach-
ment.
C7
Conal and number
# Control dam
S Pump station and number
te: Adapted from Sherwood and Klein, 1963
0 2 4 miles

I N7LNI

Figure 17. Low stage of the water table in the Miami area in May 1962 and extent
of salt-water encroachment.

ground water from storage west of the levee system
it downstream to the salinity-control dams. Heads of
were maintained on the upstream side of the dams.

and conveying
about one foot
Comparison of

FLORIDA GEOLOGICAL SURVEY

figures 16 and 17 shows the expansion of the cone of depression of
the Miami well field near Canal C-6 (Miami Canal) between 1945
and 1962. Pumpage increased from 40 to 80 mgd during this period.
The cone of depression along Canal C-2 surrounds the Alexander Orr
well field, which did not exist in 1945.

CANAL DISCHARGES

The discharge in several canals was studied to evaluate surface-
water discharge characteristic from Conservation Area 3B, Area B, and
Area A. A background for the study period (Jan. 1960 to Dec. 1963)
is provided by the monthly-mean discharge in the Miami Canal from
1940 to 1963, figure 18. The geographic dividing point between the
"Miami River" (downstream) and the "Miami Canal" (upstream) is
located approximately 4 miles inland from Biscayne Bay, figure 19.
Maximum discharge usually occurs in October at the culmination of
the rainy season; minimum discharge of less than about 100 cfs, gen-
erally occurs in May of each year.
The difference in magnitude of the discharges during the wet pe-
riods of 1947 and 1960 attest to the improvement of control works,
and the construction of the levee system during that interval. Although
rainfall in 1960 was about comparable to 1947 (table 3) the maximum
monthly mean flow was 1,270 cfs in 1960 as compared with 3,600 cfs
in 1947. This results from a combination of factors: (1) as noted
previously, maximum water levels in Area B were 2 to 3 feet lower
in 1960 than in 1947; (2) the levee system prevented direct surface-
water flow from the Everglades from reaching Area B; (3) the im-
proved canal system permitted more rapid runoff from Areas A and
B and this minimized surface- and ground-water impoundment prior
to the hurricane rains.
In table 4, annual-mean discharges (1940-63) are compared with
the 24-year median discharge of 530 cfs. Below average flows generally
persisted during the 1960-63 study period. The above average flows
in 1960 are attributable to record, antecedent rainfall in 1959 and to
the heavy rains of tropical storms Donna and Florence in 1960.

STAGES AND DISCHARGES IN THE MIAMI CANAL
The Miami Canal (C-6) is the largest canal that transects Area B.
Continuous recordings of stage and discharge are available at Stations
F, G, I, and J since 1961 (see locations in figure 19 and key to stations

z

0
0

FLORIDA GEOLOGICAL SURVEY

TABLE 4.-COMPARISON OF ANNUAL-MEAN DISCHARGES IN THE MIAMI
CANAL AT N.W. 36th STREET WITH THE
24-YEAR MEDIAN, 1940-63.

Calendar Annual mean Percent of
year discharge (cfs) median

1940
19411
1942
1943
1944
1915
1946
1947
1948
19-49
1950
1951
1952
1953
1954t
1955
1956
1957
1958
1959
1960
1961
1962
1963

710
828
753
317
312
383
630
1.412
1.178
795
426
395
544
1130
909
(28
260
551
802
707
815
291
157
117

in table 5.) The daily discharges for the years 1961-63 are plotted
in figure 20. This data provides the basis for separating the contribu-
tions to flow in the Miami Canal from Conservation Area 3B, Area
B, and Area A.
The flow characteristics at the four gaging stations on the Miami
Canal are influenced, depending on location, by ground-water inflow,
control-dam operation, well-field pumpage, and tidal flow. At Broken
Dam (F) the flow is primarily from underseepage from Conservation
Area 3B. The underseepage produces a rather steady, slowly chang-
ing flow pattern. The effect of the operation of the control dam at
N.W. 36th Street is usually reflected along the entire reach of the

REPORT OF INVESTIGATIONS No. 47

AREA B

EXPLANATION
*- Droinage divide
QA Stage ond discharge gaging
slollon
C2
C Canal and number
maL CaControl dam ond number
1csi Pump station and number
Note: Locations keyed by 16ller
to table 5.
0 2 4 milms

Figure 19. Locations of gaging stations and drainage areas of major canals in the
Miami area.

canal. Control changes produce the largest fluctuations in stage and
discharge at N.W. 36th Street because the gaging station is located
only 100 feet upstream from the control dam. For example, on March

S"0I "I
. C 'L ki g
___~.' __________ I

0'

REPORT OF INVESTIGATIONS No. 47

TABLE 5.-KEY TO LETTER DESIGNATIONS IN FIGURE 19 FOR
RECORDING STAGE AND DISCHARGE GAGING STATIONS
IN CANALS OF THE MIAMI AREA.

A. South New River Canal at S-9, near Davle, Fla.
II. Snake Creek Canal at N.W. 67th Ave., near Hiialanh, Fla.
C. Snake Crock Canal at S.29, at North Miami Beach, Fla.
I). Little River Canal at 5.27, at Miami, Fla.
E. Blrcayne Canal at S-28, at Miami, Fla.
F. Minmi Canal at Broken Dam, near Miami, Fla.
G. Miami Canal at Palmetto By-pass. near Hialeah. Fla.
II. Miami Canal at water plant, Ilnlalia, Fla.
I. Miami Canal at N.W. 36th Street, Miami, Fla.
J. Miami River at Hrickoll Ave., Miami, Fla.
K. Taminain Canal at State Highway 27, near Coral Gables, Fla.
L. Taminill Canal near Coral Gables, Fla.
M. Coral Gables Canal at Tamiami Canal, near Coral Gables, Fla.
N. Coral Gables Canal near South Miami, Fla.
O. Snapper Creek Canal near Coral Gables, Fla.
P. Snapper Creek Canal at S.22, near South Miami, Fla.

8, 1961 (fig. 20) the control was changed from fully open to nearly
closed. This produced a sharp rise in stage at N.W. 36th Street and
an accompanying drop in discharge. The drop in stage and discharge
at Broken Dam was caused by the closing of two controls (S-32 and
S-32A) in the levee-borrow canal at the same time. During the period
March 22-28, controls S-32 and S-32A were opened. This produced
an increase in discharge at Palmetto By-pass and N.W. 36th Street
with only a slight increase in stage (fig. 20). The flows are usually
larger at Palmetto By-pass than at N.W. 36th Street because water
leaves the canal between the two stations to recharge the aquifer
adjacent to the well field (near station I, fig. 19). Pumpage from the
well field varies between 70 and 125 cfs. The stage at Brickell Avenue
is not perceptibly affected by control operation because tidal fluctua-
tion in Biscayne Bay is the over-riding influence. However, the dis-
charge at Brickell Avenue reflects control operation to some extent.
The marked drop in discharge on March 9, 1961 is an example.

CONTRIBUTIONS TO FLOW IN THE MIAMI RIVER FROM
CONSERVATION AREA 3B, AREA B, AND AREA A
The drainage areas in figure 19 show that runoff from Area B is
contributed primarily to the Miami River system (C-4 and C-6). Part
of the flow from the Tamiami Canal (C-4) is diverted into the

FLORIDA GEOLOGICAL SURVEY

Snapper Creek Canal (C-2) and Coral Gables Canal (C-3). With
adjustments for these diversions, the flow of the Miami River was
separated into contributions from Conservation Area 3B, Area B, and
Area A, shown in figure 21.

2000 EXPLANATION
11-| \9 S Flow contributed from Area A
Flow contributed from Area B
SSeepoge from Conservotion Area 38

11000

500

o01' 'M'a' M'J'J'A'S'O'N'oj'I"MA'M'J'J'A'S's'N'cIN Jr'd JYAi d' dONI dl djY JYS
1960 1961 1962 1963
Figure 21. Discharge contributions to the Miami River at Brickell Avenue from Con-
servation Area 3B, Area B, and Area A.
The upper plotted line for Conservation Area 3B is the base line
above which the contribution of Area B is plotted. Similarly the upper
plotted line for Area B is the base line above which the contribution
or loss of Area A is plotted. The significance of the diagram can be
illustrated by the following examples. In March 1962, the flow of the
Miami River into Area A at its western boundary was greater than
the flow out of Area A into Biscayne Bay. The net loss of water
from the Miami River in the reach adjacent to Area A is shown by
the dip of the Area A hydrograph below the hydrograph for Area B.
High easterly winds in early March coincided with high tides and
the wind-driven salt water of Biscayne Bay flooded inland into storage
in the aquifer. The monthly mean discharge at the Brickell Avenue
gaging stations (station J in fig. 19) was 30 cfs landward (upstream).
In contrast, summation of inflow and outflow in April and May
1963 (fig. 21) again showed that water was lost from the Miami River

REPORT OF INVESTIGATIONS No. 47

in the Area A reach, but in this case the monthly mean discharge at
the Brickell Avenue gaging station was positive or seaward (fig. 20).
Except for the above two instances, the Miami River invariably gained
(picked up) water from the three areas. The relative vertical distance
between the individual curves is a measure of the contribution from
each area.
Several runoff characteristics can be identified in figure 21. The
underseepage from water stored in Conservation Area 3B is perennial
and supplies a base flow of fresh water that is tapped by downstream
users. However, in spring 1962 the conservation area was dry and
the base flow was contributed entirely by ground-water underflow.
The pickup in the Miami Canal was only about 100 cfs from Con-
servation Area 3B, 100 cfs from Area B, and practically none from
Area A. The relative difference in percentage of flows in wet and dry
seasons reflects the rapid drainage of Area A. During the dry months
only a small flow accrues from Area A. Conversely, during wet periods
runoff from Area A is proportionately large. Because of this rapid run-
off in Area A and the necessity for maintaining low water levels in
the lowlands of Area B after development, the need for additional
storage of water in the conservation area in dry periods is thus evident.
The total flow in the Miami River contributed by Conservation
Area 3B, Area B, and Area A was 520,000 acre-feet or about 725 cfs
during the period June 1962 to May 1963 (fig. 21). The Conservation
Area seepage comprised 33 percent of this total, Area B 26 percent,
and Area A 41 percent.

TOTAL SURFACE-WATER OUTFLOW FROM AREA A
Area A drains to Biscayne Bay via six major canals and by direct
ground-water flow along the shoreline.1 Discharge has been measured
continuously near the mouth of each canal as follows:
Snapper Creek Canal (C-2), gage P since December 1959
Coral Gables Canal (C-3), gage N since February 1961
Miami River Canal (C-6), gage J since February 1961
Little River Canal (C-7), gage E since February 1959
Biscayne Canal (C-8), gage D since April 1962
Snake Creek Canal (C-9), gage C since January 1959
The briefness of complete record limits the analysis to that period after
April 1962. Therefore, the following runoff evaluation for all Area A
canals is for only one year-from June 1962 to May 1963.
'Canals C-1 and C-100 (fig. 5) were under construction in 1963-64 and are not included
in the analysis.

FLORIDA GEOLOGICAL SURVEY

Drainage areas for each of the six canals (fig. 19) are estimated
from ground-water level divides (figs. 14 and 15) and other knowledge
of the hydrology of the Miami area. The number in the bar column
at the left of figure 22 gives the percentage of the total drainage area
assignable to each of the six canals.
All other factors being the same, equal rainfall over the total
drainage area would produce runoff in proportion to the size of each
drainage area. Thus, the monthly mean runoff in the Miami River
should be about 43 percent of the total, while runoff from other canals
should be similarly proportioned.
In figure 22, the monthly mean runoff from each canal is plotted
as a bar graph following the same canal sequence shown by the
drainage-area bar at the left. The dashed lines are for guidance in
comparing month-to-month values. The internal numbers on the run-
off bars are the percentages of total monthly runoff for the individual
canals.
Analysis of the shift of these discharge percentages for the various
canals can be used for evaluation and adjustment of water-manage-
ment practices. During high-water periods, when the control dams
are open, the runoff percentage should compare favorably with drain-
age-area percentage for each canal. During the dry season, when
control dams theoretically should be closed to prevent loss of fresh
water, the runoff percentage of the uncontrolled canals should increase
while that of the controlled canals should decrease. Canals, other than
the Miami Canal, are controlled near their mouths in Area A. The
control dams in the Miami River system (C-6 and C-4) are located
more than 6 miles from shore. As the Miami River system is only
partly controlled it can be used as a rough comparator for evaluation
of discharge in the controlled canals.
During the relatively high-water period June through September
1962, the discharge from the Miami River averaged about 45 percent
of the total comparing closely with the 43 percent estimated for the
drainage area. During the dry season, the percentage of total discharge
for the Miami River increased to a maximum of 76 percent in March
1963 (fig. 22). This increase is a consequence of the uncontrolled
condition of the Miami Canal. In April and May 1963 at a time of
very little rainfall, the percentage runoff of the Miami Canal decreased,
but that of the Snake Creek Canal rose considerably from a theoretical
24 percent to 45 percent in April and 46 percent in May. Gate open-
ings in the Snake Creek Canal increased the discharge during this
period and caused the shift in percentage. As a further comparison,

wu 2000---I -
w I i
S Ij SNAPPER CREEK I

4 CORAL GABLES I
0 CANAL
4 300- IC-J) 150- s -

S7 -

< 9 5/SAT~NE CANAL L /

< a/ A s -- -- -4 7
w le--8)

JUNE JULY AUG SEPT OCT NOV DEC JAN FE MAR APR MAY
1962 196000
z LruTTE RIVER nf
A cCANAL j
W BISCAYNE CANAL ..

21SAW CREEK [/1 %
CANAL e/,,'24 V

JUNE JULY AUG SEPT OCT NOV DEC JAN ". MAN APR MAY
1962 1963

FLORIDA GEOLOGICAL SURVEY

the runoff percentage for the Snapper Creek Canal gradually decreased
to zero in April and May 1963. Thus, analysis of the shift of discharge
percentages can be used as a tool for evaluation and adjustment of
water-management practices. For example, the previous comparisons
show that dry-season discharge from the Snake Creek, Biscayne, and
Little River Canals is proportionately large compared to the size of
their drainage areas. Examination of the operating criteria for the
control dams might lead to improved water management in these
canals.
The total discharge from all canals in the Miami area was 929,000
acre feet during the period June 1962 to May 1963. This is equivalent
to a yearly mean surface-water runoff of 1,280 cfs. Based on sizes of
drainage areas and on the percentage contributions to the Miami River
system (see previous section), it is estimated that about 50 percent of
this total discharge (about 600 cfs) can be attributed to contributions
from Conservation Area 3B and Area B. After implementation of the
Area B plan, division of flow will tend to occur along the boundary
between Area B and Area A. Contributions from Area A will flow
seaward, whereas contributions from Area B and Conservation Area
3B will be pumped westward. Thus, even in a dry period (such as
the analysis period 1962-63) the Area B plan will have considerable
potential for conservation of fresh water.
In order to fully capitalize on this potential, consideration should
be given to supplementary installation of small pumps (100 to 400
cfs capacity) at both the levee-side and the eastern side of Area B.
For intermediate-to-low water levels in the conservation area, such
pumps would permit ideal flexibility of water control. At intermediate
water levels in the conservation area, underseepage could be recycled
back to the conservation area at the same time that water could be
released eastward into Area A for prevention of salt-water encroach-
ment. When the conservation area is dry the east-side pumps would
assist in maintaining adequate fresh-water head near the coast by
pumping water seaward from Area-B canals into Area-A canals.

EVALUATION OF THE AREA B FLOOD-CONTROL PLAN
Coincident with the creation of useable land for urban expansion,
the flood-control plan for Area B has many features which can be
utilized for improvement of the water-resources position of southeast-
ern Florida. Steady-state electrical analog studies were made to pro-
vide insight on the vast changes in hydrology that will come about
through implementation of the plan. The land-fill requirements in

REPORT OF INVESTIGATIONS No. 47

Area B will be arrived at as a compromise of the economics of raising
the level of the land ($1,000 to $1,500 for raising an acre of land one
foot) and of the cost of the pumping system needed to protect the
housing developments with lowered fill requirements. This section will
be devoted to an appraisal of the plan in the light of past observations
of water level. The conditions of September 1960 after hurricane
Donna and tropical storm Florence passed through the area are selected
as the basis for the appraisal. The conditions that occurred then are
immutable facts under the present semi-improved drainage system, and
success of the plan must come from improvements over this recent base
condition.

WATER LEVEL MAPS
The water-level contours of September 1960 (fig. 15) were super-
imposed on the contours of present land surface (fig. 10) to obtain
the water-level map of figure 23. The water levels ranged from about
1 foot below land surface at the eastern side of Area B to more than
3 feet above land surface at the western side. The volume of water
in storage above land surface amounted to about 8.6 billion cubic feet.
Consider the height to which land surface would have to be raised
if this observed above-land volume of water were to be stored below
land surface in the pore spaces of earth fill. Assuming that no lakes
or canals were dug, approximately 5 feet of earth fill with an estimated
porosity of 20 percent would have to be placed at the contour repre-
senting a water depth of +1 foot (fig. 23), 10 feet would have to be
placed at the +2-foot contour, and 15 feet at the +3-foot contour
in order that the water table would not rise above land surface under
rainfall conditions similar to those of 1960.
Verification of this idea can be recognized in southern Dade County
in the high-water contour maps of 1947 and 1960 (figs. 14 and 15).
Because land surface is generally quite high in this area and because
canals C-1 and C-100 did not exist in these years, the water table rose
to more than 10 feet above sea level. Obviously, in Area B land-filling
alone, without pumping, would be prohibitively expensive and econom-
ically infeasible.
A water-level map of the distance between the assumed compacted
land surface (fig. 12) and the water surface during September 1960 is
shown in figure 24. If sufficient water could be removed by pumping or
by gravity drainage to hold the water level at the same altitude as that
of 1960, (a recently observed level) this map would represent the
minimum thickness of landfill that would be required after all peat and

FLORIDA GEOLOGICAL SURVEY

I! EXPLANATION

CCanal and number
9 Control dam
Pump sotion d number
0-o z 4m1le

Figure 23. Water levels in feet above (+) or below (-) existing land surface during
September 1960, subsequent to passage of Hurricane Donna and tropical
storm Florence.

black muck had disappeared by oxidation according to the assumed
compaction formula of the Corps of Engineers. (See section entitled
Present and Future Land Surface Altitude.) The volume of water that

REPORT OF INVESTIGATIONS No. 47

EXPLANATION
Assumed compocltd lond surface
bosed on 100% loss of organic
soils obowe 3ft. m.s.l and 50%
C/O compoclion o orgonic soils
Sbetbro 3ft. m.s.l.
Caonl and nwn
= *o Conlrol doa
= Pamp slaion and number

0 2 4 mlles

Figure 24. Water levels of September 1960, in feet above (+) or below (-) assumed
compacted land surface.

would have to be removed to hold the water level at the 1960 level
would be that amount which could not be stored in the pore spaces of
the land fill about eight-tenths of 8.6 or 6.9 billion cubic feet. If all

FLORIDA GEOLOGICAL SURVEY

this water were necessarily pumped at the proposed total pumping rate
of 13,400 cfs, 6 days would be required to remove the excess water
assuming return flow by underseepage from the conservation area at zero.
The above computations tend to be academic because, after imple-
mentation of the plan, pre-storm water management probably will
prevent the water from rising to the levels of 1960. The main purpose
of this discussion is to demonstrate that the water levels must be low
enough prior to the occurrence of the design storm (12.79 inches) to
provide sufficient capacity for water storage in the sediments (20 percent
porosity) and in the canals and farther backyards (100 percent storage),
see table 2. The Corps of Engineers has proposed that this storage
capacity be provided by reducing fill requirements to 4 feet above msl
in the farther backyards (table 2). At the point where the water rises
above ground surface, 100 percent storage of water will occur and further
water-level rise will relate inch for inch to the amount of rainfall that
exceeds the capacity of the pump system to remove it. Thus, by per-
mitting temporary above-ground storage of water in part of the sub-
division lots, the water-level rise will be minimized to a calculated level
of 5 feet above msl. The pump system, supplemented by gravity drainage
to the ocean, is designed to lower water levels from 5 feet to 4 feet above
msl within 5 days after the design storm. The Federal Housing Authority,
however, indicates that FHA backing of home loans probably would
not be forthcoming for homes where water was to be temporarily stored
in the farther backyards.
The Area B plan is complex and great changes in the hydrology of
the Miami area will result from its full implementation. The analog
models presented later give insight on future water levels in Area B.
Because of this insight, the present design may be altered. Obviously,
new analog studies are required to assess each new design.
ANALOG STUDY
The laminar flow of ground water through a porous medium under
a hydraulic-head differential is analogous to the flow of electrical current
through a conductive medium under electrical potential (voltage)
difference. The correspondence between the basic laws and the con-
tinuity relationships of liquid and of electrical flow has lead to the
development of several types of analog models for solving complex
boundary problems (Skibitzke, 1960; Stallman, 1961; Brown, 1962;
Rovinove, 1962; Walton and Prickett, 1963).
The equipment used in this study provides steady-state solutions to
hydrologic problems. The known boundary conditions of hydraulic head
and flow are simulated by applying D.C. voltage and current to elec-

REPORT OF INVESTIGATIONS No. 47

trically conductive graphite paper. Impermeable boundaries are modeled
by cutting the paper; hyper-conductive boundaries such as streams or
canals are usually modeled by silver paint applied to the surface of the
paper. As hydraulic-head loss is observed when water moves through
a canal, the highly-conductive paint (with no voltage loss) does not
represent the hydraulic gradient in the canal realistically. An improvi-
zation was made in the present analog study by using resistor chains
tapped into the paper at equivalent distances of about one mile. The
resistor chain served as a partial short-circuit of the conductive paper
and qualitative information on head distribution in Area B during pump-
ing was provided.

BOUNDARY CONDITIONS
Many assumptions are involved in setting up the analog model for
Area B. The boundary conditions in particular represent a combination
of past observations and visualization of possible future parameters of
the water-control system. Though the results of the analog are considered
no more than qualitative, they give realistic insight of head distributions
that would result from the present plans.
The applicability of the results of the analog-model study is affected
by the following assumptions shown in figure 25:
1. The head in Conservation Area 3B, west of the seepage-reduction
levees, was modeled at 10 feet above msl for convenience. This head is
about 1.6 feet lower than the highest observed head on the discharge
side of S-9, but the relative head differentials shown by the model may
be adjusted to a higher base if desired. Plans (Corps of Engineers, 1963)
for the area west of L-31 indicate that water in this area will not be
controlled during the rainy season but will be at a level of about 8.5 feet.
Near the end of the rainy season in November, the water level in this
area will be lowered to 5.8 feet by pumping to permit agricultural
activities. The observed water level was 8.7 feet at well G 596 in Septem-
ber 1960 (fig. 9 and fig. 15) and the head at L-31 is modeled at 8.5 feet.
2. A fixed hydraulic boundary of 4 feet above msl extends along
the eastern side of Area B from the South New River Canal (C-11),
(fig. 25) to the vicinity of C-3 and then gradually rises to 7 feet, west-
ward along the southern edge of Area B. Referring to the high-water
map of September 1960 (fig. 15), heads of 4 to 5 feet occurred along the
eastern side of Area B; the 4-foot boundary was selected as realistic for
the future on the basis of these observations. Heads of 8 to 9 feet above
msl occurred along the southern edge of Area B after hurricane Donna.
However, the improvement of Canal C-1 and the new construction of

FLORIDA GEOLOGICAL SURVEY

EXPLANATION -'/ 1 -I_ /

-m -- C -,. O C

L-30, L-31, and L-33.

C-100 can be expected to reduce maximum water levels in the future;
the southern fixed boundary has been adjusted to assumed levels (4 to
7 feet) that appear realistic for rainfall conditions similar to those of
September 1960.
3. Dams (proposed by this report) are positioned in the feeder
canals approximately at the boundary between Area A and Area B
(fig. 25). It is believed that such control dams will almost necessarily
be a requisite of the flood-control plan to facilitate water control in both
wet and dry periods. The design discharge of the larger pump stations
(3,900 cfs) is nearly as great as the highest gravity-flow discharge
observed in any of the existing canals (4,060 cfs, Miami Canal at Hialeah,
October 13, 1947). Theoreore, it is doubtful that the position of the
water-level divide separating westward flow to Area-B pumps and east-
ward flow to Biscayne Bay can be predicted. In consideration of the
large discharge capacity in Area B, it would be possible for some of the
flood waters of Area A to move inland into Area B and thus delay the

_~~ 1

REPORT OF INVESTIGATIONS No. 47

dewatering of Area B. Studies in the Snake Creek Canal (Kohout and
Leach, 1964, p. 22) show that salt water can move a mile in four hours
under density gradient alone. To avoid any possibility that salt water
might move inland along the bottom of the canal at high tide and come
under the influence of the Area-B pumps, the control dams are believed
essential and are programmed into the model at arbitrary positions along
the east side of Area B (fig. 25).
4. A dense, branching network of quaternary, tertiary, and secondary
canals will discharge water into the feeder (primary) canals of Area B.
Thus, the water-level gradients required for water to move through
the feeder canals to the pump stations will be one of the major controls
of head distribution throughout Area B. Although no size has been
assigned specifically, the feeder canals will be large, probably compa-
rable to the Miami Canal. The following set of data for a measure-
ment of maximum discharge in the Miami Canal at Hialeah on October
13, 1947 illustrates the magnitude of gradient that may be encountered
in the Area-B feeder canals during pumping.
Width: 107 ft.
Area of cross section: 1,320 sq. ft.
Average depth: 12.3 ft.
Discharge: 4,060 cfs
Cage height at Hialeah: 7.22 ft.
Gage height at N.W. 36th Street: 4.33 ft.
Distance between stations: 2.05 miles
Gradient: 1.4 ft./mile
The coefficient of roughness (n) in Manning's formula is computed
at 0.035 from the above data. The Corps of Engineers (1961, p. A-12)
have indicated that a coefficient of roughness of 0.035 will be used for
designing all canals. Using this coefficient in Manning's formula, a
graph relating depth, gradient per mile, and discharge for a canal 125
feet wide has been prepared, figure 26. The width of 125 feet has been
arbitrarily selected as a practical width for a large feeder canal. The
dashed curves are for a canal of rectangular cross section; the solid
curves are for a canal of trapezoidal cross section.
The discharge contemplated for two of the pump stations (S-202
and S-203, table 1) is 3,900 cfs. Figure 26 shows that in a canal 20
feet deep and 125 feet wide a discharge of 3,900 cfs would produce
a gradient of 0.19 ft per mile in a canal of rectangular cross section
and 0.52 ft per mile in a canal of trapezoidal cross section. Assuming
that a water level of 4.0 ft at the eastern side of Area B is a correct
appraisal for future flood conditions, the hydraulic gradient consistent

FLORIDA GEOLOGICAL SURVEY

S. T ril ri, frm M i b h

the borrow canals from the pump intake.
T I AIl-

0 01 02 03 04 05 06 07 08 0.9 10 II.
WATER-LEVEL GRADIENT, FEET PER MILE
Figure 26. Theoretical relations, from Manning's formula, between hydraulic gradient,
discharge, and depth for a canal 125 feet wide of rectangular and trapezoidal
cross sections.
with a discharge of 3,900 cfs in a feeder canal 10 miles long, would
drop the head at the intake side of the pump to about 2.1 ft above
msl for a rectangular canal and 1.2 ft below msl for a trapezoidal
canal. Thus, a head near mean sea level at the intake side of the
pump appears to be realistic for full-capacity pumping after the plan
is implemented.

RESULTS OF THE ANALOG STUDY

Two boundary conditions are modeled: (1) In figure 25 the levee
borrow canals are free to discharge water directly to the intake side
of the pump: (2) In figure 27, control dams are installed to isolate
the borrow canals from the pump intake.

BORROW CANALS WITHOUT ISOLATING CONTROL DAMS
In figure 25, the head at the intake side of all pumping stations is
assumed to be 0.0 feet msl. Underseepage beneath the levee would be

REPORT OF INVESTIGATIONS NO. 47

picked up by the borrow canals and water-level gradient toward the
pump stations would divide about half way between stations. This
gradient in the borrow canal could not be modeled adequately and
the head throughout the canal was fixed at 0.0 msl. Maximum under-
seepage would occur with this method of operation but in those parts
of the area where seepage-reduction levees are planned, the total un-
derseepage would be minimized. This is shown by the two schematic
inset profiles pointing to the north end of L-33 and L-30 (fig. 25). In
areas where seepage reduction levees are constructed (profile B), the
10-foot head differential would be spread across a distance of 3,000
feet compared to about 150 feet for profile A. If no ponding occurs
between the levees, the flow of water through the aquifer would be
reduced in proportion to the relative reduction of water-level gradient
(profile A to profile B).
Before seepage reduction (S-R) levees were contemplated, Klein and
Sherwood (1961, p. 22) computed the total underseepage for a ten-
foot head differential across L-30 near S-201 at 540 cfs per mile-432
cfs by underflow through the permeable aquifer and 108 cfs through
the levee itself. This quantity is based on a transmissibility of 3.6 x 100
gpd/ft. The transmissibility at the north end of L-33 is about 6.0 x 100
gpd/ft (fig. 5) and a ten-foot head differential there would result in
a relatively higher underflow by a factor of about 2 times that near
S-201. As a comparison with the computed underflow of 432 cfs per
mile by Klein and Sherwood (1961, p. 21), the following computation
indicates the magnitude of horizontal laminar flow through the per-
meable part of the aquifer for a 10-foot head differential across the
3,000-foot distance intervening between the S-R levee and L-30; the
black muck and dense limestone will contribute a negligible amount
of horizontal flow:
Q = TIL
where: Q is the flow rate in gpd, T is the transmissibility in gpd/ft,
I is the hydraulic gradient in feet per foot, and L is the length of sec-
tion, in feet, through which the quantity Q flows.
Q = 3,600,000 gpd/ft x 10 ft x 5,280 ft/mile
3000 ft
= 63.4 mgd per mile = 95 cfs/mile
Thus, the S-R levees can be expected to reduce underflow from
432 to 95 cfs per mile, a factor of about four. The calculation assumes
that water will not be ponded between the two levees. During periods
of heavy rainfall some ponding probably will take place. A reasonable
situation might be considered where the total head differential of 10

FLORIDA GEOLOGICAL SURVEY

feet is equally divided: 5 feet across the S-R levee and 5 feet across
L-30. Using the graph and computing technique of Klein and Sherwood
(1961, p. 21) for this 5-foot ponded condition, the underflow would
be doubled to 127 mgd/mile or 190 cfs/mile, and seepage directly through
the levee materials would be 54 cfs, a total of 244 cfs/mile.
Ponding between the S-R and main levees during the design storm
is realistic and can be included in calculations for the entire levee
system, as follows: The previous calculation indicates that the effect
of ponding with a 5-foot head differential will increase the underflow
beneath L-30 from 95 cfs/mile to 190 cfs/mile, a factor of two. Thus,
increasing the computed quantities of underflow by a factor of two in
those parts of the levee system where seepage-reduction levees are
contemplated should yield a useful evaluation of the effect of 5. feet
of ponding between the levees. The calculations apply to boundary
conditions as set up for the analog model of figure 25. The distribu-
tion of transmissibilities in figure 5 indicates about 6 to 7 mgd/ft along
the northern part of L-33 and 3 to 4 mgd/ft near S-200 and S-201.
The transmissibility along the southern part of L-30 and along L-31
is assumed to be 8 mgd/ft. The effect of the S-R levee is assumed to
be nil for one quarter mile on either side of a pump station. Table 6
summarizes the computations.
Based upon hypothetical, but realistic parameters, the total under-
seepage is computed at about 13,000 cfs for the full western side of
Area B. Under the conditions set up in the analog model of figure
25, pump capacity of this amount would be necessary to produce and
maintain the steady-state distribution of water levels. By the simple
expedient of isolating the borrow canal south of S-203 with a control
dam, 5,000 to 6,000 cfs would be removed from the total underseepage
figure (table 6).
The final steady-state distribution of heads (fig. 25) indicates that
maximum dewatering would occur at the western side of Area B if
control dams were not placed in the levee-borrow canals to isolate
them from the intake sides of the pumps. Consistent with the fixed
boundary at the eastern side, no dewatering would occur there under
the conditions imposed in the model. As resistor elements are the
same size, this implies that the modeled canals are also uniform in
size. The measured voltage at the resistor contact points indicates the
water-level response of such canals to the imposed boundary conditions.

BORROW CANALS WITH ISOLATING CONTROL DAMS
The analog model of figure 27 shows the steady-state head distri-
bution that would result if control dams were installed to isolate the

TABLE 6.-UNDERSEEPAGE FOR THE BOUNDARY CONDITION OF
NO CONTROL DAMS IN THE LEVEE BORROW CANALS.

Seepage through
levee materials
(Klein and Sherwood,
Underflow 1961, p. 22.)

Assumed average Length Q Q for 5 ft head
transmissibility Q = TIL of reach in reach differential Q
Location (fig. 25) (mgd/ft) (cfs/mile) (miles) (cfs) (cfs/mile) in reach Total

North end of Area B to I mi. north of S-200 5 132 3.0 7921 54 162 954
%4 mile north to 1 mile south of S.200 4 465 0.5 232 54 27 259
, mile south of S.200 to 1 mile north of S-201 4 105 0.5 1051 54 27 132
14 mile south of S-201 to % mile southwest of S.201 3.6 418 0.5 209 54 27 236
14 mile southwest to 1 mile southwest of S-201 3.6 95 0.75 1421 54 40 182
1 mile southwest of S-201 to bend in levee 5 132 3.0 7921 54 162 954
Bend in levee to % mile north of S-202 6 188 3.0 1,1281 54 162 1,290
%1 mile north to 1% mile south of S-202 7 813 0.5 406 54 27 433
%, mile south of S.202 to 3% mile north of S-203 8 211 3.5 1,4771 54 189 1,666
% mile north to 4 mile south of S.203 8 930 0.5 465 54 27 492
14 mile south of 8.203 to bend in levee 8 930 1.0 930 54 54 984
Bond in levee to south end of Area B 8 898 5.5 4,939 54 297 5,236
TOTALS ..22.25 11,617 1,201 12,818

1 Includes multiplication by a factor of 2 to adjust for the effect of 5 feet of ponding between seepage-reduction and main levee, see text.

r

i
taj
I
0

FLORIDA GEOLOGICAL SURVEY

-.------ -- -- -- ---- --- --------- L---
L. .. IA I

; AREA I o
t* A,

OP I
f / .,' .

Figure 27. Electric analog model of Area B with control dams that isolate the borrow
nal for L-30, L31, and L33 from the intake side of t pumps.

levee-borrow canals from the intake of the pump stations. The fixed
boundaries and other conditions are the same as tos of the previous

model. The isolation provided by the control dams permitted adjust-

sistor chains. Pump station S-202 with a capacity of 3,900 cfs and a
relative smElectric analog model of Area B with control dams thae lowest head ate borrow
canals for L-30, L-31, and L-33 from the intake side of the pumps.

levee-borrow canals from the intake of the pump. A head of 0.0 ms was assigned to -202. The fixed
boundaries and other conditions arell other stationed as those of the prevportioned
model. The isolation provided by the control dams permitted adjust-

relative to the current withdrawal at the pump-stat te derminus of the re-
sisttable 1) of all pump stations was dupith a cated in the model. With theand a
exeptivelyon of S-202, fixed area will prodmsl, the heads (i.e. voltages) at the
othe pump-station intakes and along the lengths ofassigned the anal were
measured current withdrawal at all other stations was proportioned
relative to the current withdrawal at S-202, so that the design discharge
(table 1) of all pump stations was duplicated in the model. With the
exception of S-202, fixed at 0.0 msl, the heads (i.e. voltages) at the
other pump-station intakes and along the lengths of the canal were
free to adjust to the flow of water (i.e. current) from the fixed external
boundaries.
The model shows that the heads at the pump-station intakes (other
than S-202) will be above 1.1 feet msl and in the case of S-203 the

REPORT OF INVESTIGATIONS No. 47

intake head will be 3 feet above msl. The drainage area of S-203 is
somewhat larger than other stations, and the branching canal is exposed
to higher heads along the external boundaries. The alinement of the
contours in the southern part of Area B (fig. 27) indicates that water
in the upper reach of the S-203 feeder canal would not flow to the
S-203 pump station but would flow through the interconnecting sec-
ondary and tertiary canals to the S-202 feeder canal. A variety of
changes as follows would alter the situation:
1. Increasing the capacity of the S-203 pump station to give an
intake head of about 0.0 msl thus lowering the head in the S-203
canal relative to the S-202 canal.
2. Increasing the size of the S-203 canal relative to the S-202 canal.
However, because the intake head at S-203 (2.99) is higher than the
upstream head of S-202 (2.21), a shift of heads could be accomplished
only by reducing the size of the S-202 canal. Verification of this can
be obtained by analysis of figure 26.
3. Retaining earthen plugs to separate the secondary and tertiary
canals of the feeder-canal systems. Because of the high permeability
of the aquifer this measure may not be effective in all cases. As the
drainage areas for the pump stations will be controlled to some extent
by ground-water divides between feeder canals, topographic divides
(i.e., the earth plugs) may not be completely reliable indicators of
flow division between two canal systems.
The discharge, gradient, and size of a canal are dependent variables
as indicated by the graph of figure 26, which only holds for a canal
125 feet wide. Selection of pump-station discharge, for example, leaves
the size and gradient of the canal interdependent until one or the other
remaining parameters has been designated. Thus, although the relative
current withdrawals have been proportioned to the pump-station dis-
charge in the analog model (fig. 27), the discharges have not been
fixed. The three parameters (discharge, size, and gradient) could be
varied in almost an infinite combination to give results similar to those
of the steady-state model of figure 27. More sophisticated transient-
state resistor-capacitor analog models that require special funding are
needed to restrict these variables to an optimum combination.

COMPARISON OF THE ANALOG MODELS
Comparison of figures 25 and 27 shows that installation of control
dams in the levee-borrow canals will radically change the steady-state
distribution of water levels. Without control dams (fig. 25), the lowest
water levels and greatest drawdowns will occur at the western side

FLORIDA GEOLOGICAL SURVEY

of Area B, but underseepage will be maximum. With isolating control
dams (fig. 27), highest water levels and smallest drawdown will occur
at the western side of Area B. The quantity of underseepage directly
recycled by the pumps will be greatly minimized for the latter method
of development in comparison to the former. This is indicated by the
spread of the 10-foot head differential over several miles (fig. 27)
compared to the spread over only 3,000 feet between S-R and main
levees (fig. 25). However, the eastward bulge of contours between
pump stations (e.g., S-201 to S-202, fig. 27) indicates that there will
be some sacrifice in ability of the pump system to lower water levels
in the western part of Area B if isolating control dams are installed.
Thus, depending on finalized plans of construction and of the method
of operation (i.e. whether controls are open or closed), the land-fill
requirements could have a maximum variance of about 8 feet in the
western part of Area B. Partial openings of the dams probably would
produce advantageous compromise solutions between the two modeled
extremes.
The Area B plan has evolved and changed with time. Each addi-
tional study has brought to light new evidence and a step-by-step
process of revision has taken place. The analog study should be con-
sidered qualitative because several assumptions necessary for modeling
with the simple equipment available will not be fulfilled under field
conditions. Nevertheless, the models of figures 25 and 27 are helpful
in visualizing the possible problems and the difference in approaches
or conditions. For example, both models indicate that the close spac-
ing of pump stations S-200 and S-201 will dewater the small triangle
of land between the S-200, 201 feeder canals much more efficiently
than other parts of Area B. Relocation of the S-201 pump station
southward toward S-202 would result in better equalization of the
drawdowns throughout the area between the S-200 and S-202 feeder
canals. New analog studies are required to assess the effect of such
changes.

SUMMARY
Up to the present time urban development in southeastern Florida
has been primarily along a fairly broad coastal ridge of moderately
high land that extends inland 10 to 20 miles from the shore. West-
ward from this ridge the land becomes progressively more flooded in
the lowlands of the Everglades.
The high land of the coastal ridge has largely been developed and
much of the future expansion of urban areas will have to take place

FLORIDA GEOLOGICAL SURVEY

the runoff percentage for the Snapper Creek Canal gradually decreased
to zero in April and May 1963. Thus, analysis of the shift of discharge
percentages can be used as a tool for evaluation and adjustment of
water-management practices. For example, the previous comparisons
show that dry-season discharge from the Snake Creek, Biscayne, and
Little River Canals is proportionately large compared to the size of
their drainage areas. Examination of the operating criteria for the
control dams might lead to improved water management in these
canals.
The total discharge from all canals in the Miami area was 929,000
acre feet during the period June 1962 to May 1963. This is equivalent
to a yearly mean surface-water runoff of 1,280 cfs. Based on sizes of
drainage areas and on the percentage contributions to the Miami River
system (see previous section), it is estimated that about 50 percent of
this total discharge (about 600 cfs) can be attributed to contributions
from Conservation Area 3B and Area B. After implementation of the
Area B plan, division of flow will tend to occur along the boundary
between Area B and Area A. Contributions from Area A will flow
seaward, whereas contributions from Area B and Conservation Area
3B will be pumped westward. Thus, even in a dry period (such as
the analysis period 1962-63) the Area B plan will have considerable
potential for conservation of fresh water.
In order to fully capitalize on this potential, consideration should
be given to supplementary installation of small pumps (100 to 400
cfs capacity) at both the levee-side and the eastern side of Area B.
For intermediate-to-low water levels in the conservation area, such
pumps would permit ideal flexibility of water control. At intermediate
water levels in the conservation area, underseepage could be recycled
back to the conservation area at the same time that water could be
released eastward into Area A for prevention of salt-water encroach-
ment. When the conservation area is dry the east-side pumps would
assist in maintaining adequate fresh-water head near the coast by
pumping water seaward from Area-B canals into Area-A canals.

EVALUATION OF THE AREA B FLOOD-CONTROL PLAN
Coincident with the creation of useable land for urban expansion,
the flood-control plan for Area B has many features which can be
utilized for improvement of the water-resources position of southeast-
ern Florida. Steady-state electrical analog studies were made to pro-
vide insight on the vast changes in hydrology that will come about
through implementation of the plan. The land-fill requirements in

REPORT OF INVESTIGATIONS No. 47

in the lowlands west of Miami. The U.S. Army Corps of Engineers
and the Central and Southern Florida Flood Control District have
devised a plan known as the Area B Flood Control Plan to make part
of these lowlands suitable for housing development.
Large perennially flooded tracts in the Everglades have been sur-
rounded by levees to form water-conservation areas. The marginal
lowland (elevations from 4 to 7 feet above msl) that lies between
these conservation areas to the west and to the coastal ridge to the
east has been designated Area B by the Corps of Engineers.
The Area B Plan calls for an integrated system of land fills, drainage
canals, and large-capacity pumps to control the flood hazard. After
development, huge pumps with a total capacity of 13,400 cfs are pro-
posed to dewater Area B during the rainy season, by pumping water
westward over the levee system into Conservation Area 3-B.
The ultimate altitude of the land surface for urban development
in Area B will be arrived at as a compromise of the economics of land
filling ($1,000 to $1,500 per acre foot) and of the cost of a pumping
system needed to protect the housing developments under lower fill
requirements. The basic problem is how to make this lowland area safe
from floods or at least as safe as possible with techniques, construction
methods and concepts of hydrology now available so that the develop-
ment home sites will be sufficiently safe from flooding to be a good
financial risk for banks and other lending institutions, and for the
Federal Housing Authority to guarantee the housing loans. The plan
is complicated by the fact that highly permeable limestone underlies
the area and that the underseepage beneath the levee may be large
enough under certain circumstances to be equal to the full capacity
of the pumping system.
This report has gathered together basic hydrologic facts that have
been accumulated over a period of more than twenty years so that
the effect on water levels caused by works of the Central and Southern
Florida Flood Control Project constructed between 1949 and 1962 might
be evaluated. These facts show that levee construction and improve-
ments in the drainage system caused water levels in Area B to be 2
to 3 feet lower in 1960, a hurricane year, than in 1947, also a hurricane
year, despite comparable rainfall accumulation for the two years.
Under drought conditions higher fresh-water levels were maintained
behind salinity-control dams in 1962, a very dry year, than in 1945, a
dry year before control dams were installed. However, Conservation
Area 3-B was dry in 1962 and sufficient water could not be delivered
downstream to maintain fresh-water heads. Water levels upstream

FLORIDA GEOLOGICAL SURVEY

from salinity-control dams were about 1 foot above msl in the dry
spring months of 1962. Such low water levels are insufficient to pre-
vent saltwater intrusion into the underlying limestone.
Further evaluation of the Area B Plan as proposed by the Corps
of Engineers Survey Review Report of 1961 was accomplished through
the use of steady-state electrical analog models. Two boundary con-
ditions-w-ith and without water-control dams to isolate the levee bor-
row canals from the pump-station intakes were modeled. Without
control dams the lowest water levels will occur at the western side of
Area B and underseepage from Conservation Area 3-B will be maximum,
controlled by an estimated 10-foot head differential across the 3,000-
foot distance intervening between seepage-reduction and main levees.
Arithmetic calculations for this boundary condition indicate that the
underseepage for a total head differential of 10 feet would amount to
about 13,000 cfs if water is ponded to a depth of 5 feet between
the seepage-reduction and main levees during heavy rainfall. Thus
for this assumed worst expected condition almost the full capacity of
the planned pumping system would be required to recycle the under-
seepage back to the conservation area on a steady-state basis.
If dams were installed to isolate the levee borrow canals from the
intake of the pump station, the underseepage would be minimized be-
cause of the spread of the 10-foot head differential over several miles
compared to the spread over only 3,000 feet between the seepage-re-
duction and main levees. However, highest water levels would occur
at the western side of Area B and this would require higher fill require-
ments in that area. Compromise solutions between the two modeled
extremes could be obtained by partial openings of the isolating control
dams.
The designed discharge of the larger pump stations (3,900 cfs) is
nearly as great as the highest gravity flow discharge observed in any
of the existing canals (4,060 cfs, Miami Canal at Hialeah, October 13,
1947). In consideration of the large discharge capacity in Area B it
would be possible for some of the flood waters of the presently urban-
ized Area A to move inland into Area B and thus delay the dewatering
of Area B. Also there would be a possibility that salt water might
move inland along the bottom of the canal at high tide and come
under the influence of the Area B pumps. Therefore control dams
are believed to be essential to fix the point of hydraulic separation
between flow toward the ocean and inland flow toward the Area B
pumps. It appears that the boundary between Area A and Area B is
a logical location for these control dams and that the best position

REPORT OF INVESTIGATIONS No. 47

for the dams is in the main feeder canals approximately at this boun-
dary. In this way water control will be facilitated in both wet and
dry periods. Proper operation of the control dams will cause a division
of flow so that contributions to the canal from Area A will flow sea-
ward, whereas contributions from Area B will be pumped westward.
Thus water which now unavoidably is wasted to the ocean by seaward
flow in a high-water period will be pumped westward into storage in
the conservation area.
The Area B Plan will have considerable potential for conservation
of fresh water and in order to fully capitalize on this potential con-
sideration should be given to supplementary installation of small pumps
(100 to 400 cfs capacity) at both the levee side and the eastern side
of Area B. Such pumps would permit ideal flexibility of water control.
At intermediate water levels in the conservation area, underseepage
could be re-cycled back to the conservation area at moderate rates at
the same time that water could be released eastward into Area A for
prevention of salt encroachment.
When the conservation area is dry and no water is available directly
from the conservation area, the proposed east-side pumps would assist
in maintaining adequate fresh-water heads near the coast by pumping
water seaward from Area B canals over the proposed control dams into
Area A canals.
The estimated increase in population from about 1,000,000 in 1960
to 4,000,000 in 1995 is expected to cause water use in the Miami area
to increase from 230 mgd (345 cfs) to 1.4 bgd (2,170 cfs). This rate
of water use for a year's time would be equal to a volume of water
about 10.5 inches deep covering an area of about 2,800 square miles,
or an area extending 28 miles inland from the coast and 100 miles
southward from Lake Okeechobee to Everglades National Park. This
volume of water is almost one-fifth of the average rainfall over the area
and is equal to the average surface runoff from this area. As Fort
Lauderdale, West Palm Beach, other coastal cities, agricultural interests,
and Everglades National Park will require a share of this water, it be-
comes apparent that increasing water needs will eventually approach
the availability of fresh water in the hydrologic system. In considera-
tion of these continually growing water needs, the Area B plan should
be conceived not only as a flood-control plan but also as an important
factor for beneficial control and management of all water resources in
southeastern Florida.

FLORIDA GEOLOGICAL SURVEY

of Area B, but underseepage will be maximum. With isolating control
dams (fig. 27), highest water levels and smallest drawdown will occur
at the western side of Area B. The quantity of underseepage directly
recycled by the pumps will be greatly minimized for the latter method
of development in comparison to the former. This is indicated by the
spread of the 10-foot head differential over several miles (fig. 27)
compared to the spread over only 3,000 feet between S-R and main
levees (fig. 25). However, the eastward bulge of contours between
pump stations (e.g., S-201 to S-202, fig. 27) indicates that there will
be some sacrifice in ability of the pump system to lower water levels
in the western part of Area B if isolating control dams are installed.
Thus, depending on finalized plans of construction and of the method
of operation (i.e. whether controls are open or closed), the land-fill
requirements could have a maximum variance of about 8 feet in the
western part of Area B. Partial openings of the dams probably would
produce advantageous compromise solutions between the two modeled
extremes.
The Area B plan has evolved and changed with time. Each addi-
tional study has brought to light new evidence and a step-by-step
process of revision has taken place. The analog study should be con-
sidered qualitative because several assumptions necessary for modeling
with the simple equipment available will not be fulfilled under field
conditions. Nevertheless, the models of figures 25 and 27 are helpful
in visualizing the possible problems and the difference in approaches
or conditions. For example, both models indicate that the close spac-
ing of pump stations S-200 and S-201 will dewater the small triangle
of land between the S-200, 201 feeder canals much more efficiently
than other parts of Area B. Relocation of the S-201 pump station
southward toward S-202 would result in better equalization of the
drawdowns throughout the area between the S-200 and S-202 feeder
canals. New analog studies are required to assess the effect of such
changes.

SUMMARY
Up to the present time urban development in southeastern Florida
has been primarily along a fairly broad coastal ridge of moderately
high land that extends inland 10 to 20 miles from the shore. West-
ward from this ridge the land becomes progressively more flooded in
the lowlands of the Everglades.
The high land of the coastal ridge has largely been developed and
much of the future expansion of urban areas will have to take place

FLORIDA GEOLOGICAL SURVEY

REFERENCES

Brown. Russell H.
1962 Progress in ground-water studies with the electrical-analog model:
Jour. Am. Water Works Assoc., v. 54, no. 8, p. 943-958.
C&SFFCD
1960 Report on flood conditions in the Central and Southern Florida Flood
Control District in September 1960: mimeographed report 26 p.

Dude County Development Department
1962 Revised edition. Economic survey of Metropolitan Miami: Miami,
Florida.
Ferguson, G. E. (see Parker, G. G.)

Hoy, Nevin D. (see Schroeder, Melvin C.)
Klein, Howard (see Schroeder, Melvin C. and Sherwood, C. B.)
1961 (and Sherwood, C. B.) Hydrologic conditions in the vicinity of Levee
30, northern Dade County, Florida: Fla. Geol. Survey Rept. Inv. 24,
pt. 1, 24 p.
Kohout, F. A.
1964 (and Leach, S. D.) Salt-water movement caused by control-dam oper-
ation in the Snake Creek Canal, Miami, Florida: Fla. Geol. Survey
Rept. Inv. 24, pt. 4, 49 p.
Leach, S. D. (also see Sherwood, C. B.)
1963 (and Sherwood, C. B.) Hydrologic studies in the Snake Creek Canal
area, Dade County, Florida: Fla. Geol. Survey Rept. Inv. 24, pt. 3, 33 p.

Love, S. K. (see Parker, G. G.)
Parker. G. G.
1955 (and Ferguson, G. E., Love, S. K., and others) Water resources of
southeastern Florida, with special reference to the geology and ground
water of the Miami area: U. S. Geol. Survey Water-Supply Paper 1255.
Prickett, T. A. (see Walton, W. C.)
Robinove, Charles J.
1962 Ground-water studies and analog models: U. S. Geol. Survey Circular
468, 12 p.
Schroeder, Melvin C.
1958 (and Klein, Howard, and Hoy, Nevin D.) Biscayne aquifer of Dade
and Broward Counties, Florida: Fla. Geol. Survey Rept. Inv. 17, 56 p.
Sherwood, C. B. (see Leach, S. D.)
1963 (and Klein, Howard) Surface- and ground-water relation in a highly
permeable environment: Internat. Assoc. Sci. Hydrol., Symp. Surface
Waters, Pub. 63, p. 454-468.
1962 (and Leach, S. D.) Hydrologic studies in the Snapper Creek Canal
area, Dade County, Florida: Fla. Geol. Survey Rept. Inv. 24, pt. 2, 32 p.

Skibitzke, H. E.
1960

Electronic computers as an aid to the analysis of hydrologic problems:
Internal Assoc. Sci. Hydrol., Comm. Subter. Waters Pub. 52, p. 347-358.

REPORT OF INVESTIGATIONS No. 47

Stallman, Robert W.
1956 Preliminary findings on ground-water conditions relative to Area B
flood-control plans, Miami, Florida: U. S. Geol. Survey open-file report,
29 p.
1961 From geologic data to aquifer analog models: Am. Geol. Inst., v. 7,
no. 7, p. 8-11.

Walton, W. C.
1963

Wolman, Abel
1961

(and Prickett, T. A.) Hydrogeologic electric analog computers: Jour.
Hydraulics Div., Am. Soc. Civ. Eng., v. 89, no. HY6, Proc. Paper 3695,
p. 67-91.

Impact of desalinization on the water economy: Jour. Am. Water Works
Assoc., v. 53, no. 2, p. 119-124.

U. S. Corps of Engineers
1953 Partial definite project report, Central and Southern Florida project,
for flood control and other purposes: Part 1, Supplement 7, U. S. Army
Engineer District, Jacksonville, Florida.
1958 Survey-review report on Central and Southern Florida project, greater
Miami area (Area B): U. S. Army Engineer District, Jacksonville,
Florida.
1961 Survey-review report on Central and Southern Florida project, greater
Miami area, (Area B): U. S. Army Engineer District, Jacksonville,
Florida.
1963 Survey-review report on Central and Southern Florida project, southwest
Dade County: U. S. Army Engineer District, Jacksonville, Florida.

FLRD GEOLOSk ( IC SUfRiW

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	Title Page
	Transmittal letter
	Contents
	Abstract
	Introduction
	Future water needs and availab...
	Geologic and hydrologic enviro...
	Evaluation of the Area B flood-control...
	Summary
	References

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