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

Abstract

Water changes information in the hydrological system, in time and space, as an environmental issue takes heed of managers and decision makers in watershed management and river engineering, which can be addressed by 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 southern hillside of the eastern north part of Alborz Mountain range in Iran with mean annual precipitation of 591 mm, mean slope of 40.48%, and mean elevation of 2750 m. The model implementation is based on 85 m and daily spatial and temporal resolution, respectively. By applying 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 evaluation model outputs, accuracy of 83.5% based on the Nash-Sutcliffe efficiency criterion and the Aggregated Measure of 85.6% indicate very good performance of model and well reproduction of stream flow. The Nash-Sutcliffe criterion for the model validation period is 77%. Estimation of runoff 73.5% comparing 74.9% observed runoff indicates the model efficiency and capability in simulation of watershed runoff and the other water balance components.