Some Aspects of the Availability of Water From the Everglades to the Everglades
National Park, Florida
By J. H. Hartwell
ABSTRACT
Much of the natural
overland flow to the Everglades National Park entered Shark River Slough.
The Slough is at the lower end of the Kissimmee-Lake Okeechobee-Everglades
drainage basin whose upper tributaries are to the north near Orlando, Florida.
Under natural conditions water from Lake Okeechobee generally overspilled
to the Everglades at a stage of about 17 to 18 feet mean sea level. Beginning
about 1882 the natural pattern of flow in the Everglades was changed gradually
by construction of drainage canals. Major construction of levees, canals,
pump stations and control structures occurred in the period from about 1906
to 1963.
Two 12-year periods,
1940-51 and 1952-63, were selected by which to compare rainfall and runoff.
The first period was a time of virtually no change in water control works.
The second period was a time of progressive construction of control works.
Rainfall in the first period was generally less than in the second. Outflow
from Lake Okeechobee to the Everglades in the first period (5.4 million
acre-feet) was more than in the second (1.5 million acre-feet) Contrarily,
flow to Shark River Slough increased from 2.4 in the first period to 5.1
million acre-feet in the second.
Runoff eastward
to the sea from the major canals during the first period was more than during
the second period. This reduction in runoff of fresh water to the sea was
in part a result of completion of the levee system east of the three conservation
areas in 1953. This levee system intercepts water that formally flowed eastward
and routes it southward through the Everglades to the Shark River Slough.
Also, other new drainage and water control works along the coastal ridge
and better water management by the Central and Southern Florida Flood Control
District played a part in this reduction.
It is concluded
that part of the increase of flow to the Shark River Slough was caused both
by the increased rainfall and the reduction in the flow to the sea through
the coastal canals.
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