Modeling of groundwater recharge dams

The purpose of this research on Büyük Cırcıp recharge dam is the estimation of stored water infiltration amount and time on the dam reservoir bed by HYDRUS-1D model. Büyük Cırcıp recharge dam is one of the southeastern Anatolia projects in Turkey located on one of minor watercourse of Euphrates River. The collected water of floods and annual rainfalls (from October to May) are controlled by this small dam with 1.75 million cubic meters volume. The recharge dam reservoir bed is concluded a 15 meters alluvium and a permeable limestone under it to groundwater-surface with about 55 meters thickness under the dam. The water seepage in Büyük Cırcıp recharge dam considered vertically in the z-direction. HYDRUS-1D software is used for modeling the water infiltration and evaluates the time of dam discharging in a different status. HYDRUS-1D model of water flow and solutes movements through the variable saturation media is one of the most widely used models. The model uses finite element method for solving the Richards flow equation in unsaturated. In addition, the model has the option to solve non-isothermal liquid-vapor flow and heat transfer functions. In this study, the model calculates amount and time of infiltration effectively with two considered situations; 1)100-years river flood and 2) annual flow. Results show that the time to fill up the dam depends on the raised hydrograph curve while the time to empty is related to the hydrogeological character of the reservoir bed materials. A sensitivity analysis used for hydraulic conductivity of the alluvium with the model. According to the results, technical recommendations suggest improving the efficiency by implementing a group of wells to accelerate water infiltration through the upper low permeability layer. The annual recharged potential groundwater of the basin was reported 97 hm3/year, however, this study shows that the infiltrated water into the ground through Büyük Cırcıp dam is about 10 hm3/year, which is one of 13 dam projects are planned to be implemented by GAP.