Title: The Human Impact on Florida's Weather
Full Citation
Permanent Link: http://ufdc.ufl.edu/WL00002531/00001
 Material Information
Title: The Human Impact on Florida's Weather
Physical Description: Book
Language: English
Publisher: ENFO
Spatial Coverage: North America -- United States of America -- Florida
Abstract: The Human Impact on Florida's Weather, October 1983
General Note: Box 10, Folder 22 ( SF Water Modification - 1981-83 ), Item 1
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
 Record Information
Bibliographic ID: WL00002531
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text


By W am Barada
"Everybody talks about the weather but nobody does anything
about it." (Charles Dudley Warner 1890)

This quotation (often mistakenly
attributed to Mark Twain) is still
repeated today, but unfortunately it
is no longer true. Man's activities are
causing drastic changes in weather
patterns on regional, national and
global scales. Virtually all of these
changes are accidental...most are
due to the cumulative effect of many
small-scale, ifntpendent decisions,
and the results, which are invariably
adverse, range from disastrous to
As Terence M. Thomas of the
Rosenstiel School of Marine and
Atmospheric Science, University of
Miami, said in 1970, "A naturally
evolving ecosystem undergoes
successional changes which, as
discussed by Odum (1916), 'are
orderly processes of community
development' and which 'culminate
in a stabilized ecosystem...'" But,
Thomas says, ".. contrary to natural
ecosystem development the result of
man's influence has been that of
ecosystem destruction."
Reid A. Bryson, Professor of
Meteorology and Director of
Environmental Studies at the
University of Wisconsin, stated in
1971, "Man's activities may be
producing pollutants in quantities
that rival nature." He pointed out
that the snoh~b which il
a symbol of
many years, is
pollution "wh e
prosperity of nations,
their health, and even modifies the

very physical and biological
environment in which we all live."
A Massachusetts Institute of
Technology (MIT) study reported,
"There is little doubt that man, due to
environmental reshaping, has
changed the climate of large regions
of the earth."
One of the most remarkable and
most thoroughly documented of
these phenomena is the impact of
cities and urban sprawl on local

The MIT study shows that waste
heat and pollution around cities
markedly alters local climates. As a
result, cities tend to receive more rain
and less snow than surrounding areas
- as much as 30% more rain in some
Bryson describes cities a't
resembling a rocky island in a seaof
surrounding countryside. And, lik;
islands, cities tend to develop a "sea
breeze." The heat produced bi the

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Infooatlon Coter, S Oran Ava Winter Paek, Fhloa M) .
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Page 2, ENFO
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ENFO Is Lblihd mrx ors e times a
year. te cements eKpsemd are those
of dte meho, who are mulMe ,E
their apuracy, and do a iaecestMi
NfIW L opinions t. .of rida Con.
s.aao. und, u nc. A onm n
original areA Sr publication to the
Gaswd Grow
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TanialeMee, FL 32303
Editorial staff:
ei Paratngton Poegy Lan*
Copyriht @1963 Florida CMiMrwtion
Foundation, Inc. All Uits MeaNeld.
(ISSN: 0276956)

buildings, processes, and the bodies
of people make cities warmer than
the surrounding countryside. This is
particularly true at night because the
concrete, brick and asphalt absorb
and store heat from the sun which is
released at night. Also, very little heat
is used to evaporate water in a city as
compared to the countryside. Thus,
more city heat is available to heat air
than in the country while less heat is
re-radiated to the atmosphere
through the turbid city air. Con-
sequently, a city would be warmer
than the country even without the
addition of combustive heat, and the
combustive heat production in New
York in mid-winter is estimated as 2
1/2 times the solar energy input.
The warmer part of a city is called a
"heat island" and is considered a
climactic indicator of "thermal
pollution." These "heat islands"
develop the&i own air circulation
patterns. As the warm city air rises,
the cooler suburban ar flows inward
toward the center. The suburban air
is replaced by city air that rises and
flows out toward the countryside.
then sinks. Air pollutants such adust
from traffic, smoke from exhausts
and industrial smoke stacks and
power plants, mineral particles and
other pardtulates, are kept in
suspension by the turbulent air and
swept toward i enter of the city.
The result is a meFne-shaped cap of
dirty air over the city bat Is called a
"dust dome." The "dust dome" and
air circulation patterns are well
developed o*. whenr windfwe tIght
and a c ty fonSs compact.
"Clearly," ef&soA"ys., 'it can be
almost eliminated with careful
planning of green belts, industrial
centers and similar configurations.
"When winds are stronger than 5-4

Catoon fro the 194 Florida Calamiy Calendar, BEO's ilumba cokeco of 10 ream why
we don't need to promote growe. Mi.nmu requeted contribuon: $54 each plu $1J0 or

miles per hour," states Bryson, "the The average fossil fuel power plant
dust dome breaks down into a uses about 40 million gallons of water
downwind plume that may extend each day, enough to supply a city the
for many miles." New York's dust size of Tampa. Coal and oil burning
plume has been followed to Iceland, power plants also produce sulfur
and that of Los Angeles to Nebraska. dioxide and nitrogen oxides which
Some city air particles "are react with water vapor in the
especially effective as nuclei on atmosphere to form acid rain, a
which condensation of water may phenomenon that is responsible for
occur," says Bryson. "Some are the acidification of lakes, rivers and
effective at controlling the freezing groundwaters; the acidification and
temperature of water droplets, and release of metals from soils; possible
some promote condensation at reduction of forest productivity;
relative humidities below saturation. possible damage to agricultural
As a result, cities tend to have more crops; deterioration of building
rain (especially on weekdays) and finishes and materials; damage to
much more fog than do country statuary; and possible contamination
areas, and apparently they may of drinking water from metals
produce downwind effects which released in soils and pipelines.
result in rather spectacular changes To ENFO's knowledge, no studies
in the quantity and character of the have been made of the impact of
precipitation." Florida cities on local rainfall
Stanley A. Changnon, Chief, patterns, but there is every reason to
Illinois State Water Survey, believe that they do get more rain
lCtwig 7 IL, reported in 1962 that and more air pollution than the
a sjRi impact of the city of St. surrounding rural areas. This is
Loulrris environment found that, particularly sad in Florida because
duri~ "'e summer, precipitation another remarkable and well
aibunts increased approximately documented climatological
10 downwind of the city. He also phenomenon is that many of the
said, "It is common to observe the world's great deserts were created by
formation of cunulus clouds over the man's alteration of the environment
coolg towers of power plants." and many respected scientists
ugXftges on to say, "The wet believe that wetlands drainage may
cq kEy for a 2200 megawtt be causing the Florida peninsula to
i nt constructed in Illinois has a heat gradually become a desert.
output equal to nearly 15% of the city
of St. Louis and the output is MANMADE DESERTS
concentrated in an area of 0.25 The earliest prediction that human
square miles." environmental destruction was

~ ----a;,---~;

ENFO, Page 3

converting Florida into a desert was
made by John Kunkel Small in his
book, "From Eden to Sahara,"
published in 1929 by The Science
Press Printing Company. Small made
a botanical exploration of several
thousand miles of the Florida
peninsula in April and May of 1922
and states in his preface, "The
wholesale devastation of the plant
covering, through carelessness,
thoughtlessness, and vandalism in
the Peninsular State, prehistoric and
historic, was everywhere apparent."
He goes on to say, "It may be said,
however, that the plant covering has
had to contend with destruction and
changes for ages, and would reassert
itself in one form or another in time.
For example, local hammocks and
pinelands might restore themselves
in comparatively short periods, but
the Lake Okeechobee region might
take a million years."
On page 82 of his book, Small
writes, "Here we were again very
forcibly impressed with the terrible

destruction which is returning
Florida to its primitive geological
condition, namely, a barren desert.
Drainage and fire! The two processes
are tending to eliminate all native life
from the State. We made incursions
into the remains of the old marginal
hammock of the lake (Okeechobee).
This hammock has been referred to
both in its virgin condition and after it
had been ravaged by the axe and by
fire. The wanton destruction
continues! We walked through the
skeleton of the hammock. The once
deep humus (muck soil) was gone. In
its place white sand met the eye. Even
the ashes of the humus had been
washed away. Some of the giant
cypress trees (Taxodium distichum)
were prostrate, some were standing
either dead or alive, but only to
emphasize the almost complete
destruction! Where the root-systems
of the big cypress trees were once
buried in several feet of humus so
spongy that one could walk on it only
with difficulty, not a bit of humus

remained. The root-systems, with
their accompanying "knees," stood
anchored only in sand, and one could
crawl or even walk through the
network of once subterranean
brdnched roots. Thus the magnificent
monument that took ages to
construct has been wrecked within
the fraction of a generation."
On page 110, Small quotes the
Spanish explorer, Alvar Nunez
Cabeza de Vaca, as a graphic
description of vandalism by Florida
"Those from further inland have
another remedy, just as bad or even
worse, which is to go about with
firebrand, setting fire to the plains
and timber so as to drive off
mosquitoes, and also to get lizards
and similar things, which they eat, to
come out of the soil. In the same
manner, they kill deer, encircling
them with fires, and they do it also to
deprive the animals of pasture,
compelling them to go for food
where the Indians went."

(From On the bydrogeology of the Somtbwers Florid WaW Managemet Disrict by Ganmd G. Pake, thtouho-if 6rtesy of the author)

Page 4. ENFO

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Small also quotes Bartram, writing,
"There is, as yet, but little naked
sandy desert but should the weather
continue a few years longer as dry as
it has been for the last two years -
and fires should rage as extensively
destroylpg the vegetation a large
portion of the maritime part of
Georgia on the frontiers of Florida
would be rendered likethe deserts of
Arabia. Were I a member of the
Georgia legislature, my most stren-
uous exertions would be made to
prevent, by law, the burning of the
forests which impoverishes the
land and does incalculable. min ef,
without one single advantage
resulting from it. Yet many of the
stupid people do it, to destroy the
rattlesnake make therufrw -
and I believe for the fun oflookingt
On page 112, Small wries, "It Is
true that constant change involving
destruction is a natural prome a
well as an artificial one. However,

nature's method is relatively slow
and, as a rule, orderly, and results are
usually finished constructive -
and satisfactory, while man's
methods are crude and rapid, and
result in great disorder. This is
indicative of Florida's tomorrow.
Yesterday a botanical paradise
Tomorrow,the desert!"
Small goes on to say, "Here is a
unique l Dorado, mainly a tongue of
land, extending hundreds of miles
into tepid waters, reaching almost to
the Tropic of Cancer, where the
flouisti of temperate, subtropic, and
tropic not only meet, but mingle;
where the animals of temperate
regions associate with those of the
tropics. As much as possible of this
natuil history museum should be
preserved, not only for itsbeauty, but
abo for its educational value, for it is
within easy reach of a majority of the
populations of the United States."
Imall was somewhat premature in
his prediction of the "desertifica-

tion" of Florida. But his warning is
now being repeated by a number of
modern scientists and authors.
Ecolost Arthur R. Marshall stated
in 1982 that, "In the 1940s and '50s
three South Florida authors Philip
Wiley, Hervey Allen, and Marjory
Stoneman Douglas- often discussed
the possibility of Florida's becoming a
desert. They knew that many great
deserts of the world lie in the same
latitude as the Florida peninsula...
that in fact, South Florida's lushness is
a circumtropica oddity. They were
concerned then that drainage of the
Everglades, which had already been
under wayfor more than 40 years,
would disrupt the hydrologic cycle
and dry it up like the tropical
The arid bands which circle the
earth at Florida's latitude of 20 to 30
degrees from the equator are south
Texas, northern Mexico, Baja
California, the Gobi Desert, north
and south Africa, and Australia. As

--------ENFO, Page 5
ENFO, Page 5


Art Marshall says, Florida is an oddity.
Its abundant rainfall is what separates
it from the other tropical deserts in
the same latitude.
Also of concern to Marshall and
the other authors is the fact that many
of the world's deserts are either
manmade or are expanding due to
man's activities.
A United Nations conference on
water at Mar del Plata, Argentina, in
1977, reported that vast areas of
prime agricultural land and natural
water control systems are
disappearing each year due to
manmade environmental changes.
The combination of deforestation,
overgrazing, river channelization,
and wetlands development is
denuding the land of essential,
water-retaining vegetation. As a
result, rich topsoil is being washed
into the sea or blown away by the
wind, and great deserts of the world
are expanding into once lush food-
producing lands.
The U.N. studies show that western
deserts of the United States are
expanding and more than 250,000
acres of North African farmland are
lost to desert each year.
Changnon (1982) pointed out that
deforestation and the conversion of
grasslands to cultivation or pasture
are cited as the cause for the drying
out of Eastern Europe through the
loss of evapotranspiration of mois-
ture to the atmosphere, which
drastically reduced the amount of
Changnon also stated thai
overgrazing has been responsible for
the formation and/or spread of
deserts. The present advance of the
Sahara Desert southward into the
Sahel region of west-cefttal AlMca
was cited as an example, ..
One of the mrnt -emka
climate changes due t aoi6l
was described by Bryson in n
said the "dustiest of all dese
Rajputana Desert in dl.
amazingly, the air over this
a water content compare o
some very rainy tropicafo
The desert air also has 4a
point in summer and....
clouds. Scintists whto
the area believe 'li-
desert at all.but rsiN t
It is the most d
desert in the
scientists suspected thmti
goat herds that roa~W e1"
destroyed the grass and caused the

land to convert to desert. This
suspicion was reinforced by the fact
that archaeological studies show the
area was not always a desert.
The goat theory was tested by
fencing off a plot of ground to
exclude the goats, sheep and other
grazers. Bryson states, "Nothing was
done inside the fence except to let
Nature have its way and in less than
two years there was a tall, rich native
grass, except within one goat-neck
distance from the fence."
The burning of agricultural residue
can dramatically affect an area's
climate by increasing the amount of
particulate matter to the atmosphere.
An example of this cited by
Changnon is the burning of sugar
cane residue in Australia which
overseeded the atmosphere and
reduced the amount of precipitation.
Another major cause of desert
formation or spread, according to
Changnon, is wetlands drainage
which reduces the moisture flux and
in general increases the surface
temperature. This is particularly
interesting to the United States and
Florida because drainage has dried
out vast areas of former wetlands
which are being converted to pasture
or gobbled up by urban sprawl at a
fantastic rate.
A U.S. Fish and Wildlife survey
disclosed that, in the 20 years
between the 1950s to the 1970s, the
conterminous United States lost over
nine million acres of wetlands. The
annual average net loss was 458
thousand acres, and 439 thousand of

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

these were inland wetlands. Major
losses were in vegetated wetlands
which averaged a net loss of 553
thousand acres per year.
The Fish and Wildlife survey did
not give a state-by-state breakdown
of wetland losses but it iscertain that
Florida would be high on such a list.
In fact, the loss of wetlands due to
drainage is so severe in South Florida
that some scientists who have studied
its effects believe the peninsula is in
serious danger of becoming a desert.
Florida begins just north of the
Tropic of Cancer, between Havana
and Key West, at latitude 24 degrees,
33 minutes. The coastline extends
more than 1,000 miles more than
any of the contiguous states and
the land of the peninsula is so flat that
an elevation of 25 feet above mean
sea level is a hill, and the 120-foot
high Green Swamp is a mountain by
comparison. The average rainfall is 56
inches, enough to cover Florida with
a lake four feet deep if it all could be
retained. The State has more than
7,000 lakes ranging in size from one
acre to almost one-half million acres.
But most of the lakes are so shallow
they are of little use for water storage
because they often lose as much
water to evaporation as they receive
in rainfall. If it were not for its
abundant groundwater supplies and
vast expanses of wetlands, Florida
would probably be semi-arid or a

Page 6, ENFO

Under relatively pristine
conditions, before the year 1900,
South Florida was as much as 75%
wetlands, according to the authors of
Who Knows the Rain?, published by
Friends of the Everglades. When the
summer rains came, lake water levels
rose to spread over surrounding
lowlands, and meandering rivers and
streams overflowed into floodplains.
Vast marshlands and swamps were
inundated and a sheet of water
seeped slowly toward the sea. Marsh
vegetation, fish and waterfowl
thrived; water table aquifers rose to
bathe the roots of thirsty upland
vegetation; grazing wildlife fed on
the new greenery; the deeper Flori-
dan Aquifer was recharged, and
marine life flourished in brackish
coastal marshes and estuaries.
To the early settlers, however,
wetlands were the enemy, and
Florida's policy for many years was to
give away, or sell at ridiculously low
prices, land beneath lakes, swamps,
marshes and shallow bays to anyone
who could drain and fill them. The
result was a network of canals that
drained wetlands to the sea. Inland
areas saved time and money by
pumping the surface water down
drainage wells.
"Instant real estate" was created
from dredge and fill and subdivisions
were built in floodplains, dried-out
lake bottoms, and shallow coastal
estuaries. The filled land could
handle routine storms, but hurricane
floods brought disaster to thousands
of people. Florida's history is the story
of repeated catastrophes from floods
brought by major tropical storms and
hurricanes. But after each calamity,
bigger and better drainage system.
were constructed and more piopit
were enticed into flood-prnoi
wetland homes.
After a 1a bttfkine btew
out of Lake and

Engineers wao Ai
"flood monster.". lOk
was "flood

sail ater.m0
and in
well fields,
oxidized, and e
and burned.
But the Corps' projects we'e.
designed to handle only normal rainy
seasonjC~ 9iO usuallyy the one-in-

ten-year storms), not floods from
hurricanes or major tropical storms.
And in 1947, two hurricanes brought
more flood disasters.
This brought on the formation of
the Central and Southern Florida
Flood Control District, which joined
hands with the Corps in building
flood control projects that
channelized and drained almost
every river, lake, and swamp from
Orlando to both coasts and
southward to the Keys. The 100-mile-
long Kissimmee River was
channelized in the 1960s, and vast
areas of floodplain marshland were
drained. The Corps, in justifying the
project to Congress, stated, "Some
600,000 acres in the Kissimmee Basin
were flooded for varying durations
during the major flood of 1947." The
year 1947 was the wettest in 17 years.
Central and South Florida were hit
with one hurricane and two tropical
depressions that occurred in rapid
Dr. Patrick T. Gannon, Sr., a
meteorologist formerly with the
National Hurricane and Experimental
Meteorological Laboratory in Coral
Gables, states that 35% of Florida's
pristine wetlands are gone. A major
item of conservationists' concern is
that, although the state now has laws
prohibiting dredge and fill, large
areas of wetlands are still being lost to
dredge and fill each year, with no
permit required from any official
agency local, state or federal.
(Legislation is being developed by

Sen. Patrick Neal's Citizen Advisory
,Committee on dredge and fill issues,
which would protect upland
wetlands. This will be reported in
later ENFOs.)
These are the inland wetlands:
swamps, marshes and dried-out lake
bottoms that are not connected to a
surface body of water. According to
Reese Kessler, Dredge and Fill
Permitting Supervisor in the Orlando
office of the State Department of
Environmental Regulation, isolated
wetlands do not require a dredge and
fill permit. He also said that the size of
the wetland area is not a factor. If it
dries up each year it is excluded from
DER regulations.
This was confirmed by Helen
Stilchfield. Office of the DER Deputy
Director of Environmental Programs
in Tallahassee, who said. "If a wetland
i, not contiguous to a water body, no
state agency regulates dredge and fill.
Not to my knowledge." She did say
that the Corps of Engineers may
exercise jurisdiction at its discretion.
Apparently local governments also
ignore these wetlands. The Osceola
County Planning Department stated
that they never deny a zoning
application due to drainage
Thus, unconnected wetlands are
being dredged and filled throughout
Florida and nobody pays any
attention unless the drainagefloodsa
neighbor's property. The standard
technique is to dig "retention ponds"
and use the spoil to fill the wetland

*111 "


EN1O fage 7

above flood stage. The subdivision
lots are then sold as "waterfront
property," because the ponds fill
with groundwater almost as soon as
they are dug.
These manmade lakes and farm
ponds can be seen throughout
Florida. Since no permits are
required and no records are kept, the
total wetland area lost is unknown.
Vegetated wetlands, whether they
are connected to a surface water
body or not, are vital to the
functioning of Florida's hydrologic
cycle. In fact, the tremendous
volumes of water vapor that ascend
into the atmosphere by evapotran-
spiration of wetlands are the fuel
which drives Florida's rain machine.
The destruction of wetlands results in
a loss of this fuel (atmospheric
moisture), the rain machine is
damaged, and the amount of rainfall
is drastically reduced.
South Florida, from the headwaters
of the Kissimmee River in the lakes
near Orlando, through the
Kissimmee River Valley, Lake
Okeechobee, and the Everglades to
the ocean, is a single hydrological
unit. Before man disrupted this
system, the Everglades consisted of
9,000 square miles of South Florida's
28,000 square miles, an area that has
been described as "a shallow saucer
tilted almost imperceptibly toward
the south and west with a wide break
in the side along the Gulf of Mexico."
The rainfall pattern is relatively
uniform south of latitude 28 degrees
(roughly between Tampa and Cocoa
Beach) with wet summers and
relatively dry winters. In the Miami
area about 75% of the annual rainfall
comes during the rainy season, late
May through late October. Near
Orlando the rainy season percentage'
is a little less and near Tallahassee
the rainfall is more evenly distributed
from season to season. The winter
rains are usually associated with cold
fronts that move down from the
north. Summer rains are predomi-
nantly from thunderstorms and
tropical disturbances or hurricanes
that occur occasionally.
Dr. Patrick Cannon states that the
summer hurricanes and the winter
cold fronts are large, powerful global
systems (synoptic features) that
overpower whatever local weather
conditions are generated. For this
reason Cannon says that local, or
mesoscale, conditions are usually

overlooked or ignored. This can lead
to serious mistakes because, as
Cannon says, "Of the annual
precipitatip amount (in South
Florid approximately 80% falls
during the sumner rainy season. Ten
to 15% is.de to optical storms. This
leaves 69 of annual rainfall which is
convective (e.g., anderstorms) in
The sea breeze, which oranizes
the thunderstorms, is formed
because the land and shallow
wetlands warm faster than the
adjacent body of water. The warm air
over the land rises and a sea or lake
breeze is formed as the cooler air
over the water flows inland to replace
the warmer air over the land. This
warm air rises, cools, and flows over
the water to replace the air that
moved inland, and a circulation cell is
formed. At night the reverse occurs
because the land cools faster than the
Sea and lake breezes are very
important to South Florida's climate
and to the functioning of the rain
machine. As an example, the peat
and muck soils south 6f Lake
Okeechobee that have been drained
are at least 9F. colder than
surrounding wetlands. The reason is
that peat and muck have a high heat
conductivity when wet. But when the
water table is lowered, top layers dry
.out and cool rapidly at night.
Consequently, during cold spells
there is a land breeze toward the lake
instead of from the lake.
Florida's rain machine is powered
by the energy that is taken up from
wetlands as latent heat by evapotran-
spiration on sunny days, causing
vapor to rise high into the
atmosphere. This vapor condenses as
clouds and returns to the land as
rainfall. "In addition to the locally
derived rainfall within the basin,"
states Ait Marshall, "the warm and
humid air masses rising from the
wetlands often trigger moist sea
clouds blowing inland over the
peninsula Into rainfalls thus
gaining an-extra supply of fresh water
from the sea."
In Friends of the Everglades' "Who
Knows the Rain?" Dr. Leonard
Greenfield, who taught wetlands
ecology at the University of Miami
and now serves on the Science
Advisory Board of EPA, collaborated
with Dr. Cannon in a chapter on "The
Water Cycle in South Florida." They
state, "The consequence of drainage

of surface soil or coverage with
concrete thus appears to be the
retarding of evapotranspired water
input necessary for the completion of
our local mesoscale rain cycle. It has
been calculated that at present over
South Florida south of latitude 27
degrees, human-made features or
alterations retard as much water in
one year from the evapotranspiration
process as the combined volumes of
Lake Okeechobee and the three
water conservation areas. With
insufficient input of water vapor into,
the rain cloud formation near the
inland portion of the coast, the
ultimate possible consequences are:
the movement or retention farther
inland of rain clouds or less rain
altogether, either of which results in
lower water levels in the Biscayne
Aquifer (or other coastal aquifers),
tendency toward desert formation,
and a net increase in the heat island
area and depth."
To make matters worse, the
authors state that the "heat island"
effect of coastal cities interrupts, or
breaks, the vapor/condensation
cycle of wetlands moisture and
disrupts the circulation pattern of
local lake and sea breezes.
Art Marshall, who has been
studying the human impact on
Florida's weather for about 16 years,
described the functioning of the rain
machine in a March 15,1982, article in
Sports Illustrated, titled "Anatomy of
a Manmade Drought." Marshall is
reported as stating, "Before
development changed the South
Florida landscape on a huge scale, the
slowly moving sheet of water that'
annually flowed from the Kissimmee
River basin south into Lake
Okeechobee and then spilled into
the Everglades was the key to the
region's abundant rainfall. During
the rainy season, the summer sun
would heat up this shallow sheet
water to approximately 14* above
its nighttime temperature, and
tremendous amounts of water would
ascend into the atmosphere by
evaporation ard tianspiration from
the lush plant life growing in the
marshy environment. By two in the
afternoon, the buildup in the
atmosphere was so great that heavy
rain would fall. Almost all the Water
that had risen from the wetlands
would come down again, and with it
rain from vapor that had :eoedin
over the peninsula from both the
Atlantic and GCff coasts. Now,


Page 8, ENFO

however, sheet-flow water isn't
present in sufficient quantities to
initiate the rain machine the way it
used to."
Marshall says this was the first
usageof4-ihe term "rain machine" in'
association with Florida's hydrologic
cycle. He personally dislikes it
because, he says, "There are no.r
machines'in nature." But the term has
been adopted by the public and
Marshall finds it useful in getting his
message across.
The Sports Illustrated article was
not scientific, but it got attention in
scientific circles. As a result, it
stimulated the "Symposium on the
Regional Influence of Drainage on
the Hydrologic Cycle in Florida,"
which was held on May 14, 1982, at
the University of Florida in
Gainesville. The symposium was
presented in cooperation with the
Coordinating Council on the
Restoration of the Kissimmee River
Valley and Taylor Creek-Nubbin
Slough Basin, the South Florida Water
Management District, and the
American Society of Civil Engineers.
The symposium brought together
researchers from widely diverse
background, not all of whom agreed
that evapotranspiration from
wetlands is an important source of
moisture to the atmosphere over
South Florida. As the symposium
summary stated, "Another school of
thought is that evapotranspiration
from the surface over the peninsula
contributes only a small proportion
of the total atmospheric moisture and
that a major percentage of the
moisture is imported into the region
from adjacent warm ocean areas."
Gannon pointed out, however,
that in 1973, retardation of
evapotranspired moisture due solely
to cultural features south of 27.5
degrees north latitude was estimated
as on the order of three million acre
feet or about four billion tons-- of
water. This is a net loss of atmospheric
moisture that would be even greater
today, in 1983, i
Gannon's hypothesis is supported
by the fact that irrigation increases
rainfall which demonstrates the
importance of soil moisture. As an
example, irrigation replaced dry land
farming in the high plains region of
Kansas, Nebraska, and the Dakotas
after World War It. As a result, reports
Changnon, the rainfall records over
the past 30 years suggest that the
climate may be getting wetter.
"In jh Columbia River Basin of

Washington and Oregon there
appears to be a 25% increase in
precipitation due to irrigation,"
states Changnon. He goes on to say,
"Irrigation changes the climate by
lowering the albedo (reflected heat
and light), increasing the humidity,
and lowering the daytime air tem-
As Howard T. Odum, Director,
Center for Wetlands and Graduate
Research Professor, Department of
Environmental Engineering Science
at University of Florida, stated, "In
the Everglades during the summer
months the shallow surface water
temperature can be quite high (on
the order of 350C) during the day.
The high surface temperatures result
in very high vapor pressures at
ground level. The end result is the
injection of large amounts of heat
and water vapor into the lower
atmosphere. Compared to air parcels
originating over dry surfaces the
parcels injected over the hot water
surfaces are much more buoyant due
to the additional sensible and latent
heat. As a result, the warmer, more
moist parcels possess greater
buoyancy and therefore a greater
potential for more vigorous cloud
development compared to the
ambient air masses. There doesn't
seem to be much doubt that the
present drought is in some part
influenced by larger scale weather
processes, but the point is this: If a
normal water surface had been
maintained in the Everglades, then
perhaps the present drought would
not have been as severe!"
In his Interpretive Summary of the
Gainesville Symposium, Dr. Kenneth
L. Echternacht, President, Southern
Geotechnical Associates, Inc. and
Consultant to the Coordinating
Council on the Restoration of the
Kissimmee River, states, "Without
question drainage of wetlands in
Florida has led to modification in the
climate. The role of wetlands as water

conserving mechanisms is one of the
keys to the understanding of the
region. Another important factor is
the role played by the surface
properties. I feel that, qualitatively,
Gannon is correct in stressing the role
of soil moisture and ultimately the
evapotranspiration production as an
energy source and possible local
moisture source to the atmosphere
over South Florida.
"Quantitatively we still have no
idea of the amount of water vapor
supplied, or the percentage
compared to imported maritime air.
However, the importance of the
resulting buoyancy, due initially to
evapotranspiration and organized by
the sea breeze circulation, in driving
the mass and moisture convergence,
is important to the production of rain
over the peninsula."
Thus, there is no doubt that
Florida's drainage programs and the
disappearance of its wetlands have
caused a change in climate and a
definite reduction in rainfall. Dr.
Gannon states, "It has been
estimated that the drying of the soil
zones can lead to a potential
reduction in precipitation of as much
as 50% in terms of evapotranspiration
contribution. Thus it would appear
that the reduction in evapotranspira-
tion is as likely a candidate for the
recent drought as the recent lack of
tropical storm activity."
In the Sports Illustrated article,
Gannon is quoted as saying, "This
entire weather cycle has been
altered, weakened, and shifted. It's
radically different now than it was in
1900, and it appears from all the
research that we are setting up a heat
regime rather than a rainy regime in
the summer period." ;
This is supported by rainfall records
in South Florida supplied by NOAA.
A study of the rainfall accumulated
amount above or below average
(normal) from 1941 to 1980 shows a
big accumulated deficit since 1969 -

~---~r --



ENFO, Page 9
. . I ;l l J j . . .L : J L . I l i .. I .. .. . 1 J .. . 1 1 I -l l I

the year the Kissimmee River was
Cannon says that South Florida will
be faced with a long-term drought
that will-be alleviated only
temporarily by transitory, synoptic
disturbances such as tropical
depressions and tropical storms.
Art Marshall is concerned that the
process of converting Florida into a
desert may already by under way.

As Marshall has pointed out, the
sheet flow of water through the
Kissimmee River flood plain when
the river overflowed its banks during
the rainy season, prior to
channelization, extended the wet
period of the basin for four or five
months beyond the rainy season. The
wide, slow-rmoving band of water was
cleansed and purified on its way to
Lake Okeechobee; it supported
tremendous populations of water
birds and freshwater fishes; acted as a
natural, cost-free, flood control
system; and provided enormous
volumes of evapotranspired water
vapor to the atmosphere that was
ultimately returned to the basin as

Channelization of the river has
virtually eliminated these benefits.
And giant Lake Okeechobee, the
heart of South Florida's water storage
reservoirs, now often cannot provide
enough water for its users' needs.
Marshall points out that there is no
possibility that more technological
solutions similar to those of the past
will resolve the area's water shortage
Similar damage has occurred in the
Everglades, according to Marshall.
Under pristine conditions about 90%
of Everglades water was evapotran-
spired to the atmosphere. Of the
remaining 10%, some was distributed
to the shallow aquifer; some went
through the Miami and New Rivers to
tide water; and some went by sheet
flow through the region and
Everglades National Park to Florida
The Everglades "River of Grass"
was seven to eight feet dep at flood,
and 40 miles.wide with no shore.
According to Marshall, it was the
slowest-flowing river in the world
due to the flat terrain and dense
vegetation. And this stretched the
rainy season water supply for several
months, which provided flowing
surface water all, or most all, of the

The extended sheet flow enabled
muck soil formation by providing
detritus with four or five months of
wet decomposition after the rainy
season. The vegetation also purified
the water by utilizing nutrients.
The sheet flow atso supported a
fantastic population of marine
species that spend 7% to 80% of their
lives in the shallow waterof estuaries.
And the vaporized air from the
evapotranspiration of 90% of
Everglades water triggered rainfall
from the moisture-laden sea breezes
--And most of the evapotranspired
water returned to the area as rain.
All of this has been changed by
wetlands destruction. Lake Okee-
chobee receives less water than its
historic average which, according to
Marshall, was about two million acre;
feet per year, from the Kissimmee
River and its tributaries. In 1980 the
tributaries discharged 180000 acre
feet to the lake; in 1981 it was about
70,000 acre feet. As Marshall says, if
the Upper Chain of Lakes suffer. a
drought, there is no water for Lake
Okeechobee. And the lake
evaporates about as much water as it
receives from rainfall, since the river


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Page 10, ENFO

was channelized.
In the Everglades, Marshall says
that water levels are now six feet
below the historic averages. The
width of the "River of Grass" has
been cut in half, from 40 miles to 20
miles, and, according to Marshall,
"the conservation areas serve as
drying pans."
The extended sheet flow has
largely been eliminated. Marshall
says, "With the loss of sheet flow
wetland vegetation has diminished;
muck is being lost rather than
generated; water quality is
worsening; recharge of the Biscayne
Aquifer has been reduced; resources
of the Park have been degraded
including the marine fishery
resources of Florida Bay; the giant
solar collector is a fragment of its
former size and there is a darned
good chance that the hydrologic
cycle of south Florida has been
critically depressed throughout the
Everglades system "
Marshall har proclaimed for years
that Florida must repair the
Everglades system or the peninsula
will soon be unable to support its
growing population because of acute
water shortages. And the vast

majority of environmentalists in
Florida heartily agree.
Fortunately, the problems have
finally caught the attention of
responsible public officials and some
vital parts of the damaged rain
machine are now scheduled for
The Kissimmee River is scheduled
for restoration. Most of the infamous
ditch should be backfifled anda lrge
proportion of the former wetlands
will be restored. jSee August, 1963,
ENFO, "The Everglades: Headed For
Death Before It Is Ever Understood.")
Marshall reports that a number of
good things are being done to help
repair the Everglades and he is
hopeful that the momentum can be
continued so even more can be re-
Dennis Auth, Director of Executive
Planning and Coordination of the St.
Johns River Water Management
District, stated that a new rule is now
being readied for adoption that will
cover isolated wetlands that are not
connected to a surface water body.
Auth says they will be called
hydrologicallyy sensitive areas"
because they dry up. The regulation
will tie them to a combination of

plant species, topography, and soils
rather than trying to identify them by
,water regimes. Auth says that
wetlands are essentially dried-up,
vegetation-covered lakes and that
drainage converts lakes into wetlands
by drying hem ot. He claims that
Florida is "flld" with such wetlands.
His identificaion of wetlands by
plant species is particularly important
in terms of the functioning of
Florida's rain machine. Gannon says
that vegetation transpires water
vapor at a rate up to three times faster
than it is evaporated from surface
waters so the artificial lakes
excavated from wetlands are about
one-third as effective in water vapor
production as a wetland of the same
size. And most artificial ponds are
only a fraction the size'bf the former
wetlands they have replaced.
At least one of Florida's water
maagen t districts is moving
toward protecting isolated wetlands,
and perhaps others will follow suit.
if the State of Florida begins
thinkilr terms of the hydrologic
cycle, lhaps the state can yet
reste forida's rainfall pattern and
avoid transforming this tropical
peninsula to desert.





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TAMPA FL 33601-

Additional copies may be obtained for S2.00 each while supplies lst.


OCT S .1983

PERMIT NO. 3-368



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