Simulation of Water Balance Components Using a Distributed Hydrological Model in Taleghan Watershed

Information on water changes in the hydrological systems, in time and space, as an environmental issue is vital for managers and decision makers of the watersheds and river engineers. This information can be obtained using spatially distributed modeling. In this study, simulation of water balance components in Taleghan mountainous watershed is performed using the spatially distributed hydrological model, WetSpa. This area is located on south east of Alborz range in Iran with a mean annual precipitation of 591 mm, mean slope of 40.48%, and mean elevation of 2750 m. The model implementation is based on grids of 85 m pixel size and daily temporal resolution. Through application of the spatial parameters derived from three base digital maps and daily time series data as model inputs, peak discharges and flow hydrographs are predicted at any point of stream network and spatial distribution of water balance components and hydrologic characteristics are simulated. The simulated and observed hydrographs are compared using statistical and visual methods. The results revealed a very good agreement between simulated and observed data. Considering model outputs and accuracy of 83.5% based on the Nash-Sutcliffe efficiency criterion and the Aggregated Measure of 85.6%, performance of the model is assessed as very good, hence a good reproduction of stream flow and other hydrological processes. The model thus calibrated provides users with the ability of analyzing watershed hydrology response to land use/cover change.