South Atlantic Water Science Center - Georgia
2005 WATER USE
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Consumptive Water Use in Georgia, 2005
Consumptive water use is the water withdrawn that is evaporated, transpired, lost to leakage, incorporated into products or crops, consumed by humans or livestock, transferred to another area, or otherwise removed from the immediate water environment. In 2005, about 24 percent (1,310 Mgal/d) of the total water withdrawn (5.471 Mgal/d) in Georgia was consumed.
The distinction between the amount of water withdrawn for use and the amount of water consumed during use is important for water planning and management. For many withdrawals, data on the amount withdrawn that was returned to the immediate water environment (either a ground- or surface-water system) are not available. Water sales and purchases and interbasin transfers make it difficult to relate withdrawals to return flows. For example, an industrial facility might withdraw some water from wells and purchase additional water from a public supplier. Some of the total water used at that facility then might be returned directly to a stream (if it was noncontact cooling water) and some might be treated at a public or private waste treatment plant and the treated wastewater returned to a stream. Because of the difficulties in obtaining and compiling data on the amount of water returned to the environment for each withdrawal, consumptive use was estimated from the withdrawal amounts and consumptive-use coefficients by water-use category. Although estimates derived using coefficients can provide insight into consumptive water use, the results are not as accurate as metered data on withdrawals and return flows.
The consumptive-use coefficients vary for each of the water-use categories. Because public supply delivered water to domestic, commercial, industrial, and thermoelectric-power users, consumptive use is estimated for those use categories and not for public supply. The total water used in the categories is the sum of water withdrawn (self-supplied water) and water delivered from public suppliers. For domestic water use, consumptive use was estimated at 18 percent of the total use (Atlanta Regional Commission, written commun., 2007). The consumptive-use coefficient for commercial use was developed by the GWUP and supported by calculations using withdrawal and discharge data for some commercial users and estimated to be 18 percent.
For industrial and mining use, consumptive-use coefficients were determined by industry type and type of mining activity. For example, the estimated consumptive-use coefficient for the pulp and paper industry is 7 percent for 2005, whereas for the textile industry the coefficient is 13 percent. Although the coefficient is less, more water actually is consumed by pulp and paper industries than by textile industries in Georgia because of the larger amount of water being withdrawn for production.
Irrigation and livestock water uses are considered to be 100 percent consumed; that is, all of the water withdrawn was evaporated or transpired, incorporated into crops, or consumed by livestock. Irrigation in Georgia uses sprinkler and micro-irrigation methods, which do no have the large nonconsumptive amounts of water as do flood irrigation methods. Consumptive-use coefficients for thermoelectric power ranged from 0 to nearly 70 percent, and is determined by the type of plant cooling (once-through cooling or cooling towers or ponds). Consumptive use is negligible for instream hydroelectric-power generation.