Analysis of the effects of precipitation amounts on daily runoff in Gharesou basin in Kermanshah Province, Iran

Study and research on natural processes related to water including droughts and floods is necessitate for Iran. Due to difficulty to measure meteorological and hyrological elements effective on rainfall runoff processes in basins, selecting a suitable model, which is able to simulate these processes with the minimum input data, is necessary. In addition, understanding basin reaction to the precipitation amount and intensity can help water reasearchers and managers to implement approperiate measrures that reduce drought and flood damages. The main objective of this research is analysis of precipitation amount and intensity effects on rainfall runoff, and daily streamflow in Gharesou basin in Kermanshah Province (area: 5287 km2), Iran, using spatially hydrological WetSpa model. The model was applied to simulate daily runoff for about 9 years data. Results of the simulations showed a good agreement between calculated and measured hydrographs at the outlet of the basin. The model predicts the daily hydrographs with a good accuracy, 0.830 for about 6 years of calibration and 0.834 for 3 years of validation periods according to the Nash-Sutcliff efficiency criteria. Then, the model was applied to two scenarios of different amounts of precipitation in order to find the responses of the basin to them.