Estimation of Groundwater Recharge in Junggwae-Boeun Area in Ulsan City Using the Water Balance and Hydrogeological Analyses

Estimation of groundwater recharge is one of the most critical issues in sustainable management of groundwater resources. This study estimated groundwater recharge in the Junggwae-Boeun area in Ulsan City, by using the water balance and hydrogeological characteristics of geology and soil. Evapotranspiration was computed by using the Thomthwaite method, and direct runoff was determined by using the SCS-CN technique. Groundwater recharge was obtained as 266 mm/a (20.6% of the average annual precipitation, 1296 m/la), with 779 mm/a (60.1%) of evapo-transpiration and 119 mm/a (9.2%) of direct runoff. Precipitation and groundwater recharge was highly correlated, comparing with the relationships between precipitation and evapotranspiration, and between precipitation and direct runoff. This fact indicates that groundwater recharge responds more sensitively to precipitation than evapotranspiration and direct runoff do.