Test wells used in the study, Surface-Geophysical Characterization of Ground-Water Systems of the Caloosahatchee River Basin, Southern Florida, 2001, USGS WRIR 01-4084 table 1

Seven test coreholes were drilled to calibrate lithostratigraphic units, their stratal geometries, and estimated hydraulic conductivities to surface-geophysical profiles. A continuous marine seismic-reflection survey was conducted over the entire length of the Caloosahatchee River and extending into San Carlos Bay. Lithostratigraphic units that intersect the river bottom and their characteristic stratal geometries were identified. Depth to geologic contacts and hydrogeologic units, orientation of bedding, lithologic types and thickness, and sequence stratigraphy are interpreted from seismic-reflection and ground-penetrating radar (GPR) profiles. Lithologic descriptions of seven test coreholes are linked to the geophysical interpretations to provide an accurate hydrogeologic framework. Micropaleontologic and strontium-isotope data provide temporal constraints that guide correlation of reflections on seismic profiles and of lithologic units in cores.

The Caloosahatchee River Basin, located in southwestern Florida, includes about 1,200 square miles of land. The Caloosahatchee River receives water from Lake Okeechobee, runoff from the watershed, and seepage from the underlying ground-water systems; the river loses water through drainage to the Gulf of Mexico and withdrawals for public-water supply and agricultural and natural needs. Water-use demands in the Caloosahatchee River Basin have increased dramatically, and the Caloosahatchee could be further stressed if river water is used to accommodate restoration of the Everglades. Water managers and planners need to know how much water will be used within the river basin and how much water is contributed by Lake Okeechobee, runoff, and ground water. In this study, marine seismic-reflection and ground-penetrating radar techniques were used as a means to evaluate the potential for flow between the river and ground-water systems. The purpose of this report is to characterize the hydrogeologic framework of ground-water systems that are being simulated by the integrated ground- water/surface-water model for the Caloosahatchee River Basin. This is accomplished through the interpretation of geophysical, lithologic, micropaleontological, and strontium-isotope data.