Southern Everglades Application of the Regional Simulation Model
Sharika U. S. Senarath, Randy Van Zee, and A. M. Wasantha Lal
South Florida Water Management District, West Palm Beach, FL
The Everglades, the only remaining subtropical wilderness in the continental
USA, is the home to a number of threatened and endangered species. Although
the pre-drainage Everglades covered an area of approximately 11,000 km2,
urbanization and farming have reduced its area by approximately 50%. The
remaining Everglades has also changed as a result of drainage and
compartmentalization by over 2,200 km of levees and canals. This area is also
adversely affected by exotic species, nutrient enrichment, contaminants and
altered freshwater flows. The $8 billion Comprehensive Everglades Restoration
Plan provides a “framework and guide to restore, protect, and preserve the water
resources of central and southern Florida, including the Everglades”
(www.evergladesplan.org). The success of this project, one of the largest ecosystem restoration projects in the world, depends heavily on our understanding of
the quantity, quality, timing and distribution of South Florida’s pre-drainage
freshwater flow. Consequently, accurate hydrologic modeling is crucial for the
restoration of the greater Everglades ecosystem. Although, the South Florida
Water Management Model (SFWMM) developed by the South Florida Water
Management District (SFWMD) has been used in the past, its two-mile spatial
resolution and fixed grid geometry prevents it from being used to obtain detailed
hydrologic information at sub-regional scale. In addition, its limited spatial
coverage restricts it from being employed to accurately capture the flow dynamics
in areas adjacent to the Whitewater Bay and the Gulf of Mexico coastlines within
the Everglades National Park.
The SFWMD is planning to apply its Regional Simulation Model (RSM) to gather
detailed hydrologic information on a significant portion of the remaining
Everglades. The boundary of this modeling domain encompasses the Water
Conservation Area 3, the Everglades National Park and the Big Cypress National
Preserve. Primarily, this RSM application will be used to investigate the
sensitivity of de-compartmentalization on hydro-periods and stages, and to
quantify the freshwater flows to the Florida Bay. The RSM is an implicit, finitevolume, continuous, distributed, integrated surface/ground-water model, capable
of simulating one-dimensional canal flow and two-dimensional overland flow in
arbitrarily shaped areas using a variable triangular mesh. It utilizes physically
based formulae for the simulation of overland and groundwater flows,
evapotranspiration, infiltration, levee seepage, and canal and structure flows. It is
capable of simulating features that are unique to South Florida such as low-relief
topography, high water table, saturation-excess runoff, depth-dependent
roughness and very permeable soils. Since, one of the main objectives of applying
the RSM to the southern Everglades area is to investigate the impact of
compartmentalization on stage and flow, the accurate simulation of flow barriers
within the model domain is crucial for the success of this project. To this end, a
52,817-element mesh has been constructed to conform to all major levees,
highways and canals within the model domain and to simulate flows across all
major bridges and culverts. The resultant numerical model uses a mesh with an
average element size of 1.81 km2, and a one-day time step. It employs recently
updated land-use, elevation and soil data for the derivation of static model
parameters. The RSM is calibrated using historical time-series data from 1988 to
1995. The preliminary calibration results of this modeling study will be presented
for review and analysis.
Senarath, Sharika, South Florida Water Management District, 3301 Gun Club
Road, MS 4340, West Palm Beach, FL 33406, Phone: 561-682-2822, Fax: 561682-2027, ssenarat@sfwmd.gov, Question 1