The effect of different management scenarios on quantitative changes in water resources of Balekhlichai river watershed and Ardabil plain aquifer using MODSIM model

The use of optimization-simulation tools is one of the effective approaches that can play a significant role in analyzing water resources management scenarios. In this study, using MODSIM water resources planning model, the effect of different management scenarios in water scarcity conditions on water allocation planning in Balekhlichai river catchment and also the water level of Ardabil plain aquifer was investigated. Calibration and validation of the model were performed by considering the surface flow hydrograph of the basin outlet and the aquifer hydrograph using the data of the statistical period 2000-2014. Then the return flow coefficients were estimated by trial and error. The values of root mean square error and Nash-Sutcliffe efficiency coefficient in the calibration and validation period indicate the good performance of the model in simulating surface and groundwater flow and water balance components of catchment. After ensuring the accuracy of the model simulation, various management scenarios including population growth scenario (S), irrigation efficiency change (S1) and cultivation pattern and irrigation efficiency changes (S2) were examined. The results showed that under scenarios S, S1 and S2, the groundwater level drop will be equal to 8.41, 3.36 and 2.31 meters, respectively. Also, under scenarios S, S1 and S2, the percentage of agricultural demand supply in the Yamchi irrigation network from the reservoir will be equal to 38, 43 and 48 percent, respectively. Therefore, by applying water resources management scenarios, it is possible to prevent a sharp drop in the water level of the Ardabil plain aquifer in the future years and take an effective step in balancing groundwater.