Evaluation of Performance Stimulation of Surface Flow by SALAS Water Balance Model in Catchment Area of Kohgiluyeh and Boyerahmad Province

The present study has been programmed with the aim of evaluating the efficiency of SALAS water balance models (Annual and seasonal) in hydrometry stations of Kohgiluyeh and Boyerahmad Provence which had suitable statistical time period. After analyzing the hydrometrical data of the total 10 stations of the province, seven hydrometric stations were selected which had precipitation and discharge data with statistical time period of minimum 20 years. Furthermore, using “trial by error” method to achieve the lowest root mean square error (RMSE) and correlation coefficient, optimal parameters were obtained for SALAS models. The evaluation of the model function was made by using different accuracy including efficiency coefficient (CE), root mean squared error (RMSE) and coefficient of determination (R2). For calculating the efficient criteria, the values simulated by SALAS model and the values measured in hydrometric stations were used. In general, the simulation results shows that annual SALAS water balance models has estimated the flow rate value better than the seasonal one. Salas seasonal model in most cases has estimated the values less than the actual amount. In fact flows underestimated by seasonal model. Modeling results showed that Nazmkan, Saidabad, Batary and Pataveh hydrometricstations had better performance than the other stations, and Nazmakan station annual scale: RMSE= 104 and CE=0.94) and Saidabad (seasonal scale: RMSE = 93 and CE=0.88) had the best performance while Zohre, Kata and Btary stations had lower performance in comparison with the other stations. Generally it can be said that Salas model, with respect to its simplicity, can be used in the basins with no hydrometrical station and with similar climatological and geological conditions and small and even plain basins can be used for the flow of river simulation. For snowy basins, the amount of snow and the resulting runoff should also be considered in the modeling, to be exact and have a great accuracy.