Evaluating Water Resources Supply and Demand Using WEAP-MABIA (Case Study: Gadar River Basin)

Currently, numerous sub-basins located in the Urmia Lake Basin (ULB) are experiencing water shortages. Gadar River basin is one of the most important basins of the ULB in which proper water allocation and management are paramount of importance. A decision support system based on a water evaluation and planning system (WEAP) could be highly beneficial in water allocation plans at the basin scale. In this research, the WEAP-MABIA model has been used to analyze and simulate water supply and demand in the three major catchments of Gadar River basin. The year 2009 was chosen as the base year of modeling, all nodes of supply and resources were created, and the rainfall-runoff model was simulated. Then, the Gauss-Levenberg-Marquardt optimization algorithm, embedded in the PEST tool, is implemented for calibration. The efficiency of the model is proved by the Nash-Sutcliffe coefficient for the calibration and validation period, which is ranged from 0.68-0.87. Ultimately, several management strategies such as a slight increase in irrigation efficiency, fallow implementation, and cultivation of low-demanded were employed to investigate the sustainability of water resources in the Gadar River basin. The results revealed that simultaneous implementation of %10 fallow along with 5% increase in irrigation efficiency could enhance the water supply reliability, compare to status que, in Oshnaviyeh, Naqadeh and Hasanlu basins %12, %19, and %11 respectively. Hence, this scenario, with decreasing the unmet demand, would play a major role to ameliorate the water shortages in the study area.