U.S. Department of the Interior
U.S. Geological Survey
FS-131-96
Vicente Quinones-Aponte
Introduction |
Project Goal |
Background |
Research Plan |
Preliminary Model |
Refined Model |
Product Plans |
Project Schedule |
References
The South Florida Ecosystem Restoration Program is an intergovernmental effort, involving a number of agencies, to reestablish and maintain the ecosystem of south Florida. One element of the restoration effort is the development of a firm scientific basis for resource decision making. The U.S. Geological Survey (USGS), one of the agencies, provides scientific information as part of the South Florida Ecosystem Restoration Program. The USGS began their own program, called the South Florida Ecosystem Program, in fiscal year 1995 for the purpose of gathering hydrologic, cartographic, and geologic data that relate to the mainland of south Florida, Florida Bay, and the Florida Keys and Reef ecosystems.
Over the years, the construction of canals and levees has altered the natural hydrologic conditions of the Everglades. The canals and levees were constructed to convey water, prevent flooding, and store water in conservation areas for future use. The U.S. Army Corps of Engineers (COE) in Jacksonville, Fla., is planning to construct gated spillways and culverts to allow for the restoration of natural sheetflow conditions to Everglades National Park (ENP). These proposed changes may further affect the hydrologic conditions of ENP and other parts of the ecosystem, thus leading to the following questions:
Federal, State, and local agencies need to know the effect that changes in the operation of gates and control structures in canals will have on the water-budget components of the natural water systems in south Florida, including ground-water flow to Biscayne Bay.
The objectives of this project are to define the geohydrologic
characteristics of the surficial aquifer system in parts of Biscayne Bay and
apply numerical modeling techniques to estimate ground-water discharges to the
bay. An assessment will also be made describing the potential effects of some
water-management operations in canal and water-conservation areas on the rates
of ground-water discharges to Biscayne Bay.
![]() |
Figure 1 -- A flowing well in Biscayne Bay. Photograph from Kohout (1967). |
Data compiled during this project will include the collection of water-level
data, core samples, and water-quality data (especially chloride and specific
conductance data) from observation wells and test holes. The wells and test
holes will be drilled and installed offshore and nearshore in an attempt to
define the freshwater-saltwater mixing zone and the nature, location, and
quantity of ground-water flow to Biscayne Bay. Core samples will be collected
and analyzed to determine the geologic and hydrogeologic characteristics of the
subsurface material underlying the bay and near the coast. Gamma and
electromagnetic induction resistivity logs will be run at selected wells to aid
in the determination of the geohydrologic horizons and the definition of
salinity profiles. A model analysis will be performed to further define the
saltwater-freshwater mixing zone and to estimate ground-water flow to Biscayne
Bay. A preliminary ground-water flow model and a refined model will be used for
the analysis. Both models are described in detail in the next sections of this
paper. Some historical and seasonal simulations (including near predevelopment
conditions) will be performed. Additionally, an attempt will be made with the
model to estimate the location of the saltwater-freshwater zone. These data will
be made available to various Federal, State, and local agencies.
A preliminary ground-water flow model will be constructed using the SWIP
code (INTERA Environmental Consultants, Inc., 1979) as modified by Merritt
(1994). The model solves ground-water flow equations accounting for fluid
density and viscosity dependence on temporal changes of pressure, temperature,
and solute transport. Density changes are important because the differences in
density between the fresh ground water and the saline bay water affect flow and
water levels. Data from an existing ground-water flow model (Merritt, 1995),
which includes most of Dade County from Tamiami Trail south
(fig. 2), will be transferred to the new proposed model
grid using a geographic information system (GIS).
The southern Dade County model by Merritt (1995) is a comprehensive model
that subdivides the surficial aquifer in four layers (one layer is used to
represent overland flow) and considers the effects of rainfall,
evapotranspiration, canal water levels, canal control structures, areal and
vertical changes in permeability, aquifer thickness, production wells, and tidal
boundaries. All of the parameters from the southern Dade County model by Merritt
(1995) to be used in the southwestern part of the preliminary model will also be
generated for the northern and northeastern parts of the model grid using GIS
technology. Hydrogeologic data from the southern Dade County model will be
extrapolated to the area of the grid that covers Biscayne Bay. For purposes of
this preliminary model, the boundary conditions used will be constant head or
pressure, whichever is determined to be appropriate for the steady-state
simulation. Water-level data from wells, canals, and tidal gage sites will be
used to represent the boundaries. This preliminary model will be used to select
the locations for drilling test holes and observation wells and provide an
initial estimate of ground-water flow to Biscayne Bay. These data will be made
available to the Waterway Experimental
Station (the COE research group that will be performing simulations of
surface-water circulation in Biscayne Bay) and to the Jacksonville office of the
COE and to the South Florida Water Management
District for their effort on the restoration of ENP.
Data collected from the new wells will be used to test and refine the model
calibration. The boundary conditions for the refined model will be represented
using time-varying water levels in wells, canals, and tidal gate sites that will
be converted to pressure values using a correction for density of the different
model layers and water salinities. This procedure is described in detail by
Merritt (1995). A sensitivity analysis will be performed, focusing on how the
variation of the model parameters will affect ground-water flow to Biscayne Bay.
Tentative dates and the planned project activities are summarized below:
Fuller, M.L., 1904, Contributions to the hydrology of eastern United States:
U.S. Geological Survey Water-Supply Paper 102.
For more information contact:
Related information:
U.S. Department of the Interior, U.S. Geological Survey
Preliminary Model
Figure 2 -- Southern Dade County model area by Merritt
(1995) and proposed Biscayne Bay model area. (click on image for a larger
version.)
Refined Model
04/96 - 06/96: Conduct well and data inventory. Apply preliminary model
analysis to design location of wells. Select drilling sites and obtain permits.
07/96 - 10/96: Conduct nearshore corehole drilling and well
construction.
08/96 - 12/96: Conduct offshore corehole drilling and well construction.
12/96: Begin refined model construction and calibration.
04/97: Apply model to estimate ground-water discharges to Biscayne Bay
under different scenarios.
07/97: Begin writing of comprehensive report.
10/97: Continue application of the model and start model sensitivity
analysis.
10/98: Complete comprehensive report.
Griswold, L.S., 1896, Notes on the geology of southern Florida: Harvard
Coll. Mus. Comp. Zoology Bulletin, v. 28, no. 2.
INTERA Environmental Consultants, Inc., 1979, Revision of the
documentation for a model for calculating effects of liquid waste disposal in
deep saline aquifers: U.S. Geological Survey Water-Resources Investigations
Report 79-96, 73p.
Kohout, F.A., 1960, Cyclic flow of salt water in the Biscayne aquifer
of southeastern Florida: Journal of Geophysical Research, v. 65, no. 7, p.
2133-2141.
----- 1967, Relation of seawater and landward flow of ground water to
the salinity of Biscayne Bay: M.S. Thesis, The University of Miami, Coral
Gables, 98p.
Merritt, M.L., 1994, A rewetting approximation for a simulator of flow
in a surficial aquifer overlain by seasonally inundated wetlands: Ground Water,
v. 32, no. 2, p.286-292.
----- 1995, Simulation of the water-table altitude in the Biscayne aquifer,
southern Dade County, Florida, water years 1945-89: U.S. Geological Survey
Open-File Report 95-337, 88 p.
Munroe, R.M., 1930, The commodore's story: Ives Washburn Press.
Parker, G.G., Ferguson, G.E., Love, S.K., and others, 1955, Water
resources of southeastern Florida: U.S. Geological Survey Water-Supply Paper
1255, 965p.
Sewell, John, 1933, John Sewell's memoirs and history of Miami:
Miami's water supply and its source: Miami, Florida, Franklin Press, v. 1, chap.
6.
Shaler, N.S., 1890, The topography of Florida: Harvard Coll. Mus.
Comp. Zoology Bulletin, v. 16, no. 7.
Willoughby, H.L., 1898, Across the Everglades: J.B. Lippincott
Company.
Vicente Quinones-Aponte
U.S. Geological Survey
9100 N.W. 36th Street
Suite 107
Miami, FL 33178
(305) 526-2895
quinones@usgs.gov
SOFIA Project: Ground-Water Discharge to Biscayne Bay
| Disclaimer | Privacy Statement | Accessibility |
This page is: http://sofia.usgs.gov/publications/fs/131-96/print.html
Comments and suggestions? Contact: Heather Henkel - Webmaster
Last updated: 05 November, 2004 @ 10:08 AM(TJE)