Development of water-use projections for groundwater flow models in the coastal plain of Georgia and South Carolina
Fanning, Julia L.
Cherry, Gregory S.
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Future water use in the Coastal Plain of Georgia and South Carolina was estimated as part of the development of groundwater flow and solute-transport models. Two areas are being modeled—one focusing on the coastal area of Georgia and adjacent parts of South Carolina and Florida, the other focusing on the U.S. De-partment of Energy (USDOE) Savannah River Site (SRS) and surrounding area in Georgia and South Carolina (Fig. 1). Estimates of future water use in the two study areas are needed for prediction of possible future ground-water conditions. Accurately predicting future water use is important to provide meaningful results from groundwater model simulations. Several methods were used to project future water use in the two study areas. As part of the Georgia Coastal Sound Science Initia-tive, the U.S Geological Survey (USGS), in cooperation with the Georgia Environmental Protection Division (GaEPD), is developing numerical models to simulate groundwater flow and solute transport (saltwater contami-nation) in the Floridan aquifer system in the coastal area of Georgia and adjacent parts of South Carolina and Flor-ida (Fig. 1). The GaEPD defines the 24-county coastal area of Georgia to include the 6 coastal Georgia counties and 18 adjacent inland counties, an area encompassing about 12,240 square miles (Fig. 1). Total water use in this area during 2000 was about 900 million gallons per day (Mgal/d) of which about 370 Mgal/d were from groundwater sources and 530 Mgal/d were from surface-water sources. Future water use in the coastal area was estimated based on projected growth in total population and em-ployment population derived from the Regional Economic Models, Incorporated database (Phyllis Isley, Bureau of Business Research and Economic Development, Georgia Southern University, Statesboro, Ga., written commun., 2004). Because there is a direct correlation between popu-lation change and the amount of water withdrawn for pub-lic supply, a population percent change was calculated for each year from 2001 through 2035; this percentage change was then applied to reported water withdrawal data for 2000 (Fanning, 2003). Similarly, for industry, percentage change in employment population was used to estimate future growth in industrial water use. Growth in agricul-tural use was derived using a projected 5-percent annual growth in irrigation (Kerry Harrison, Georgia Cooperative Extension Service, oral commun., Tifton, Ga., 2003).