Quantification of Groundwater Recharge in the Karvan Aquifer in Isfahan (Iran) Using the CRD Model

Identification of the net groundwater recharge is essential for groundwater modeling and water resources management. Due to its simplicity and its minimum stochastic parameter requirements, the CRD model has been widely applied to estimate recharge. Rainfall is the main source of groundwater recharge in the Karvan area in Isfahan (Iran). The area is located in the semi-arid zone and there is no source of recharge other than rainfall. Estimation of groundwater recharge from rainfall is not an easy task since it depends on many uncertain parameters. The cumulative rainfall departure (CRD) model was used in this study to estimate the net groundwater recharge from rainfall. The cumulative rainfall departure (CRD) model is based on the principle of water balance and does not require much data as is the case with other conventional methods of recharge estimation. The CRD model was conducted using the optimization method to minimize the root mean square error (RMSE) between the measured and the simulated groundwater head. The results indicated that the annual amount of groundwater recharge from rainfall in the Karvan Aquifer in Isfahan is about 48.07 million m3.