Calibration and Evaluation of IHACRES Hydrological Model for Daily Flow Simulation

Major of hydrological systems are very complicated and it is not possible to understand them completely, therefore simplification is necessary to understand or control of a part of the system behavior such as water balance relationships. Hydrological models are simple structure of complicated systems in water cycle in the nature. The first goal of a hydrological model is function predict of complicated system and survey the impact of any kind of changes on system behavior. In this research IHACRES hydrological model was used to daily flow simulation and calculation of rainfall measure that be increase into streamflow, in the kasilian catchment (Area=342.86 km2) and kasilian sub catchment (Area=67.8 km2). The results was representative of delay naught between rainfall and flow in two catchments, also to values of two parameter coefficient of determination (D) and average relative parameter error (ARPE), the model streamflow in kasilian catchment more accuracy simulated than kasilian sub catchment. Altogether, in attention to values of error in flow volume (Bias), average of simulated streamflow by IHACRES model was more than observed streamflow in these catchments. Percentage of rainfall that bears hand to streamflow creation of kasilian catchment was calculated near third of catchment rainfall average and in the kasilian sub catchment for evaluation and calibration period 231 and 216 mm/yr, respectively.