Simulation of the AharChay Water Balance Using the SWAT Model

Study of water balance is absolutely important for investigation of the hydrology cycle, and preparation of water balance components in the watersheds requires many spatial data and their analyzing; so new technologies, models and tools such as GIS are needed. In this study, the SWAT model, which is a conceptual and semi-distributed model in the water and sediment balance simulation, was used in Aharchay watershed, Ahar, East Azarbayjan Province. Efficiency of the model in hydrologic simulation for this area is evaluated. Meteorology and hydrometers data of 1979-2010 was selected for this simulation; the average amount of rainfall and evapotranspiration were obtained 559.8 and 299.1 mm respectively. The period of 1982-2002 were used for calibration and 2003-2010 for validation. Calibration and validation processes were performed using SWAT-CUP software and PSO algorithm. Nash-Sutcliffe efficiency coefficients for water simulation were 0.39 for calibration and -6.7 for validation. Results showed that water balance simulation was not performed perfectly. Deficiency of required information and use of different data periods in calibration and validation were some of the effective factors which reduced the efficiency coefficients of the model.