The development of an expanded conceptual karst hydrogeologic framework in this project will be used to assist development of procedures for numeric simulations to improve the monitoring and assessment of the response of the ground-water system to hydrologic changes caused by CERP-related changes in sstage within the Everglades wetlands, including seepage-management pilot project implementation. Specifically, the development of procedures for ground-water modeling of the karst Biscayne aquifer in the area of Northern Shark Slough will help determine the appropriate hydrologic response to rainfall and translate that information into appropriate performance targets for input into the design and operating rules to manage water levels and flow volumes for the two Seepage Management Areas. Mapping of the karstic stratiform ground-water flow passageways in the Biscayne aquifer is recent and limited to a small area of Miami-Dade County adjacent to the Everglades wetlands. Extension of this karst framework between the Everglades wetlands and coastal Biscayne Bay will aid in the simulation of coupled ground-water and surface-water flows to Biscayne Bay. The development of procedures for modeling in the karst Biscayne aquifer will useful to the establishment of minimum flows and levels to the Biscayne Bay and seasonal flow patterns. Also, these improved procedures for simulations will assist in ecologic modeling efforts of Biscayne Bay coastal estuaries.
Wacker, Michael A. Robinson, Edward Gefvert, Cynthia J. Krupa, Steven L.
Carlson, J. L., Wingard, G. L., Robinson, E., Wacker, M. A.
1. Drilling about 10 test coreholes
Drilling and completion of approximately 10 test coreholes by wireline coring methods. This work provides critical data for development of a new karst hydrogeologic framework of the Biscayne aquifer that will be used in developing procedures for hydrologic modeling of the karstic Biscayne aquifer that includes areas adjacent to Biscayne Bay; produces wells that will provide information to be used in developing procedures for modeling that will benefit monitoring and assessment of the pilot projects information needs; and produces wells that will be used to develop a high-resolution hydrogeologic framework, and procedures for hydrologic modeling that can be used in research and possible model refinement to establish operating protocols of the seepage barriers.
2. Geophysical logging
Geophysical logs are acquired at completion of each test corehole above. Processing of sonic data to be accomplished using LogCruncher software. Flowmeter and fluid-temperature and resistivity data used to assist in selection of preferred ground-water flow paths in the karst Biscayne aquifer. This work will produce data necessary to produce a conceptual karst hydrogeologic model by integrating core analyses, (including molluscan and benthic foraminiferal data and interpretation of lithofacies and depositional facies), borehole geophysical logs, cyclostratigraphy, and hydrologic data.
Electronic files of geophysical logs will be archived as electronic files at the USGS-FISC-CWRS office, and paper copies and PDF file versions of log montages of all geophysical logs will be produced using WellCAD software.
3. Cyclostratigraphy and hydrostratigraphy
Data from core descriptions, thin-section petrography, paleontology of mollusks and foraminifers, construction of hydrogeologic cross sections, and measurement of porosity and permeability of core samples will be used to develop a high-resolution conceptual karst hydrogeologic framework of the Biscayne aquifer in the study area. Task will produce a conceptual karst hydrogeologic model by integrating core analyses, (including molluscan and benthic foraminiferal data and interpretation of lithofacies and depositional facies), borehole geophysical logs, cyclostratigraphy, and hydrologic data.
Core samples will be described using a 10-power hand lens and binocular microscope to determine vertical patterns of microfacies, sedimentary structures, and lithostratigraphic boundaries, to characterize porosity, and to estimate "relative" permeability. Limestones to be classified by combining the schemes of Dunham (1962), Embry and Klovan (1971), and Lucia (1995). Core-sample descriptions to be classified as rock-fabric facies and presented graphically. Horizontal and vertical permeability of numerous whole-core samples and porosity and grain density to be measured at Core Laboratories, Inc., Midland, Texas. Borehole images acquired from each test corehole will be used to quantify vuggy porosity using a method described in Cunningham and others (2004, Journal of Applied Geophysics). Molluscan analyses to be conducted by G. Lynn Wingard at the USGS Paleontology Laboratory in Reston. Core samples will be examined under a binocular microscope to observed diagnostic characteristics and compared to published species. Clay squeezes or latex casts will be made of the molluscan molds where appropriate to aid in identification. Identification of benthic foraminifera to be conducted by Edward Robinsonof University of West Indies. Thin section samples will be examined petrographically to observed diagnostic features for identification of foraminiferal type and associated depositional environments.
This task will aid in the construction of two-dimensional hydrogeologic cross sections. Development of a three-dimensional conceptual hydrogeologic framework of area encompassed by approximately 10 new coreholes. Model will be output using Environmental Visualization Systems NT-PRO software.
4. Hydrologic modeling
Initiate procedures for the application of the MODFLOW-2000 Hydrogeologic Unit Flow (HUF) pack and/or CAVE (Carbonate Aquifer Void Evolution) to hydrologic modeling of the karstic Biscayne aquifer in the study area. Development of modeling procedures for a karstic aquifer will allow more reliable simulations of ground-water flow and solution transport in the variable-density ground-water model of Miami-Dade County.
Test use of relations between porosity and permeability using e.g., the Kozeny-Carmen equation, initiate application of the MODFLOW-2000 Hydrogeologic Unit Flow package, and begin application of parameter estimation techniques to apportion the bulk permeability values to individual flow zones.
U.S. Department of the Interior, U.S. Geological Survey, Center for
Coastal Geology
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