performance comparison of three hydrological models swat, ihacres and simhyd for the runoff simulation of gharesou basin

nowadays protecting land cover, quality and quantity of water resources are important. surface runoff is one of most important reasons of soil erosion which causes sediment in reservoirs and reduction of land’s fertility and also quality reduction water of rivers. so the main issue is exact prediction of basin runoff to raining events. the hydrologic models are simplified models of real hydrologic system that helps us with studying surface runoff of basin in reaction to different entries and also better understanding of hydrologic processes. according to variety of accessible rainfall-runoff models choosing an appropriate rainfall-runoff model for a basin can be important of order of efficiency, planning and water resources management. therefore choosing a model needs recognition capability and limitations of basin models. so in this paper the efficiency of three swat, ihacres and simhyd rainfall-runoff models will be evaluated and compared. some criteria of evaluation in this study are nash coefficient, coefficient of determination (r2) and root mean square error (rmse). joint periods of simulation in these three models are chosen in a 30 year period. the simulation shows that swat with 0.8 nash coefficient and simhyd with 0.68 have the highest and lowest efficiency in calibration period. these amounts are 0.73 and 0.4 for validation period. the results show that swat model has the best efficiency in runoff simulation according to observation data during the validation period.