Hydrologic and hydraulic assessment of artificial recharge in the Sparta Aquifer of Union County, Arkansas

Abstract

Groundwater pumping from the Sparta aquifer in Union County, Arkansas, has long exceeded natural recharge, threatening the regional water supply. An alternative water-supply project, completed in 2004, now provides treated surfacewater to local industries. This conjunctive use of surface- and groundwater has allowed the Sparta aquifer to recover somewhat. Exploring further possibilities for Union County, the author has evaluated the potential of artificial recharge by well injection. A MODFLOW groundwater model was modified to simulate the aquifer's response. to artificial recharge. Results indicate that artificial recharge in this context is impractical. Injection increases hydraulic heads only locally, with the most improvement occurring where the injection is located in an existing cone of depression in El Dorado, Arkansas. Since groundwater withdrawals are already concentrated in this area, injection only reduces the net withdrawal rate. The same result could be achieved by reducing or substituting groundwater withdrawals directly, as has been observed since the completion of the alternative-supply project. The modeling results, along with analyses of surfacewater resources, suggest that continued and expanded conjunctive use is the most viable water-management strategy in Union County.