Simulation of surface runoff in Karaj dam basin, Iran

A major part of the Iranian capital drinking water is supplied from Karaj reservoir 100 km northwest of Tehran. This reservoir collects water from 849 km(2)-catchment which is undergoing accelerated changes due to deforestation and urbanization. The main objective of this study is to develop a catchment modeling platform which translates ongoing land-use changes, soil data, precipitation and evaporation into surface runoff of the river discharging into the reservoir: Soil and Water Assessment Tool, SWAT, model along with hydro-meteorological records of 1997-2011. A variety of statistical indices were used to evaluate the simulation results for both calibration and validation periods; among them, the robust Nash-Sutcliffe coefficients were found to be 0.58 and 0.62 in the calibration and validation periods, respectively. This project has developed a reliable modeling platform with the benchmark land physical conditions of the Karaj dam basin.