An aquifer test conducted in the Green Swamp area December 15-16, 1975 was designed to stress the uppermost part of the Floridan aquifer so that the leakage characteristics of the overlying confining bed could be determined. A well tapping the upper part of the Floridan aquifer was pumped at a rate of about 1,040 gal/min for 35 hours; drawdown was measured in the Floridan aquifer and in two horizons in the confining bed. Analysis of the data indicates that the transmissivity of the upper 160 feet of the Floridan is about 13,000 ft2/d, the storage coefficient is about 2.5 x 10-4, and the overlying confining bed leakance coefficient is about 2 x 10-2 to 2.5 x 10-2d-1. The vertical hydraulic diffusivity of the confining bed ranged from 610 to 16,000 ft2/d. Results of the test indicate that, in the area of the test site, a Floridan aquifer well field would induce additional recharge to the Floridan. As a result of that increased recharge, water levels in the surficial aquifer would tend to stand lower, runoff from the area would tend to be less, and, perhaps, evapotranspiration would be less than normal.

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USGS1981

Computer simulation of the steady-state flow system of the Tertiary limestone (Floridan) aquifer system in east-central Florida

The predevelopment steady-state ground-water flow system for 13 ,700 square miles of the Tertiary limestone aquifer system (known as the Florida aquifer in Florida) in east-central Florida is simulated by means of a digital computer model. The model results indicate that about 1,900 cubic feet per second recharges the aquifer as downward leakage from the surficial aquifer. The average recharge rate where recharge actually occurs (approximately 6,550 square miles) is about 4 inches per year. The maximum recharge rate is about 14 inches per year. An additional 21 cubic feet per second is recharged to the modeled area of the aquifer by means of lateral boundary inflow along the northeast boundary. The Floridan aquifer system, as simulated, discharges 1,300 cubic feet per second as springflow, 540 cubic feet per second as diffuse upward leakage to the surficial aquifer in an area of approximately 7,150 square miles and 81 cubic feet per second as lateral boundary outflow to the southwest and to the east. The average transmissivity of the upper unit of the aquifer, as simulated, is about 120,000 square feet per day while that for the lower unit is about 60,000 square feet per day. (USGS)

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USGS1980

Ground-water hydrology of the Dade City area, Pasco County, Florida, with emphasis on the hydrologic effects of pumping from the Floridan aquifer

The Dade City area, northeast Pasco County, Florida, is an area of about 260 square miles. Of the approximately 32 million gallons per day pumped from the Floridan aquifer in the area in 1975, about 16 million gallons per day were pumped from an area of about 0.25 square miles by a citrus processing plant. There are essentially two producing zones in the Floridan aquifer in the Dade City area. The upper zone is from about 10 feet above to about 150 feet below National Geodetic Vertical Datum of 1929 , and the lower zone from about 300 to about 500 feet below NGVD of 1929. There is evidence of hydraulic interconnection of the upper and lower zones of the Floridan aquifer. This appears to be highly significant in terms of the geohydrology of the Floridan aquifer in the area, particularly with regard to its ground-water flow pattern, water quality, and aquifer hydraulic characteristics. In the immediate vicinity of the citrus processing plant, aquifer transmissivity may range from 200,000 to as much as 400,000 feet squared per day. It is probable the Floridan is only semiconfined in the immediate vicinity of the citrus processing plant. High aquifer transmissivity in the area is the reason why there are only a few feet of drawdown of the Floridan 's potentiometric level even near the center of the well field.

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USGS1978

Effects of paved surfaces on recharge to the Floridan aquifer in east-central Florida: A conceptual model

The proportionate amount of surface area that can be paved in Floridan aquifer recharge areas in east-central Florida without reducing the net recharge to the Floridan aquifer is a function of many variables that include rainfall, depth to water table, depth to potentiometric surface of the Floridan, evaporation from paved areas, evapotranspiration from unpaved areas, runoff, pattern of paving, and leakance coefficient of the confining beds. Equations that incorporate those variables, except pattern of paving, are developed and coupled to produce a conceptual model that estimates relative amounts of water available for recharge and percentage of unpaved area below which Floridan aquifer recharge rates must increase. The model is not intended to be used as a basis for engineering design. Rather, its purpose is to show approximate mathematical interrelations of rainfall, runoff, evapotranspiration, percentage of paving, and Floridan aquifer recharge, and to make quantitative estimates of amounts of water available for Floridan aquifer recharge before and after paving. The allowable percentage of paving calculated in four examples ranges from 86.8 percent to 3.6 percent. (Woodard-USGS)

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USGS1977

Overlay maps of the Forest City Quadrangle, Florida; surface-drainage basins; altitude of top of Floridan Aquifer; potentiometric surface of the Floridan Aquifer and areas of artesian flow, May 1974

Explore the source record for details and available documents.

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USGS1976

Ground-water hydrology of the Cocoa well-field area, Orange County, Florida

The city of Cocoa, Brevard County, Florida, supplies water for much of central Brevard County including Cape Kennedy and Patrick Air Force Base. The water supply is obtained from a well field in east Orange County. Many of the easternmost wells in that well field yield salty water (chloride concentration greater than 250 milligrams per liter). The interface between the fresh and salty water in the west part of the well field occurs at a depth of about 1,400 feet. An upward hydraulic gradient exists between the the lower (salty) zones and the upper, or pumped zones of the Floridan aquifer in the west part of the well field. Secondary artesian aquifers in the well-field area are relatively high-yielding but are of limited areal extent. However, they are suitable as a source of water for supplemental supply or for artificially recharging the Floridan aquifer. Fresh water was transferred by siphon from a secondary artesian aquifer to the Floridan aquifer at 90 gallons per minute. Artificial recharge and recovery experiments show that it is feasible to retrieve fresh water stored in salty zones of the Floridan aquifer. (Woodard-USGS)

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USGS1975

Aquifer tests in the Summit reach of the proposed Cross-Florida Barge Canal near Ocala, Florida

Values for the horizontal and vertical hydraulic conductivity of Floridan aquifer materials are estimated by analyses of specially-designed aquifer tests at three sites along the Summit Pool reach of the proposed Cross-Florida Barge Canal for use in evaluating the exchange of water between the aquifer and the canal. Methods are described that deal with unique boundary conditions and aquifer anisotropy at two sites. Extreme aquifer heterogeneity precluded the determination of aquifer coefficients at one of the sites and probably affected the results of the tests at the other two. Therefore, the calculated aquifer coefficients reported should be regarded only as estimates. Calculated coefficients of horizontal hydraulic conductivity ranged from 0.025 to 3,500 gallons per day per square foot (0.0010 to 143 metres per day) and calculated coefficients of vertical hydraulic conductivity ranged from 0.05 to 23,000 gallons per day per square foot (0.0021 to 943 metres per day). Ratio of horizontal to vertical hydraulic conductivity ranged from 0.09 to 2.9.

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