Evaluation of WetSpa Model for Rainfall-Runoff Simulation in Semi-Arid and Mountainous Watersheds (Case Study: Bar Arye Watershed)

A review over the rainfall-runoff studies shows that, humid regions have received worth more attention than arid and semi-arid regions. So that, in this study, the rainfall-runoff process of an arid and semi-arid district, namely; Bar Arye Watershed with an area of about 112km2 and a mean annual precipitation of 307mm was simulated by using the spatially distributed rainfall-runoff model, WetSpa which has the ability to be connected to the geographical information systems. The period from 2003 to 2008 was applied for modeling. In the present study, according to Nash-Sutcliff criteria with the value of 0.69% for the validation phases it was indicated that the model has shown a good performance in modeling the rainfall-runoff. The rainfall-runoff coefficients of the observed and simulated values were equal to 0.59 and 0.57, respectively. This shows that the model has a good performance in estimating the values of runoff.