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

Hydrogeologic conditions and simulation of ground-water flow in the Greater Orlando Metropolitan Area, East-Central Florida

“…Deposits in the east part of Seminole County near Geneva are reported to range from 20 to 60 ft in thickness (Phelps and Rohrer, 1987, p. 8). The Hawthorn Group is absent in northeast Seminole and southwest Volusia Counties and the surficial and Floridan aquifer systems are separated by deposits of fine sand, shells, and calcareous silty clays present at the base of the surficial aquifer system (Tibbals, 1977;Phelps, 1990, p. 17). In the southwest part of the study area, in Polk County, unit thicknesses range from 6 to 20 ft (Grubb, 1978;Johnson, 1979 olg- I I I I I I I I ll I t I I I I I I I I I I I I I I I I I I I I I 1 I I I I I Figure 5.…”

“…Water-level and water-quality data and flow-meter logs indicate that this less permeable zone acts as a semiconfining unit that hydraulically separates the more permeable zones above and below it (Miller, 1986, p. 56). Based on this information, the Floridan aquifer system has been divided into the Upper Floridan aquifer, the middle semiconfining unit, and the Lower Floridan aquifer (Tibbals, 1981;Miller, 1986).…”

“…In 1988, about 12.5 Mgal/d of reclaimed water was used to irri- Knochenmus (1976);Lichtler (1968;Szell (1993); Tibbals (1977); and Vecchioli and others (1990) Rosenau and Faulkner (1977); U, spring and flowing well locations estimated from U.S. Geological Survey (USGS) quadrangle maps; T, spring location published by Tibbals (1990); RT, revised from Tibbals (1990), based on inspection of additional or more current data; C, estimate from data collected during current study and not included in Tibbals (1990) (Tibbals, 1990, p. 29).…”

“…Specific-capacity and normalized well-yield data collected in Seminole County by Tibbals (1977) were used to distinguish between areas of relatively high, moderate, and low transmissivity within the Upper Floridan aquifer. Specific capacity is calculated by dividing the discharge rate at a pumping well by the drawdown measured in the well.…”

“…Although the earlier Regional Aquifer-System Analysis (RASA) study conducted by the U.S. Geological Survey (Tibbals, 1981; includes the study area, the RASA model is coarsely discretized and was developed to simulate more regional flow systems. In order to improve understanding of ground-water flow conditions in the Floridan aquifer system and the possible effects of future withdrawals, the U.S. Geological Survey (USGS), in cooperation with the St. Johns River Water Management District (SJRWMD), the South Florida Water Management District (SFWMD), and the Florida Department of Environmental Protection (FDEP), began a 5-year project to develop and calibrate a more highly resolved digital ground-water flow model of the study area.…”