رزیابی کارایی مدل بارش- رواناب SIMHYD تحت سناریوهای مختلف تغییر اقلیم

Babolroud watershed and Mazandaran province of such as are that in recent years, different extreme events have been happened. On this basis, emphasize necessity to investigate further on impact of climate change on watershed runoff. This work is done by climate change and rainfall-runoff models that able to simulate and calculate of climate changes impact on hydrologic components Including precipitation, temperature, evapotranspiration and runoff. In this study, using this method, the data model HadCm3  general circulation of the atmosphere with the use of LARS WG model according to A2 (pessimist), B1(optimist) two scenarios for the time periods 2046-2065 and 2080-2099 be downscaled. Then predicted variables were introduced to SIMHYD rainfall-runoff model. The simulated daily runoff in the period 1982-2011, were selected the best period of calibration and verification with regard to the duration and optimizing statistical parameters and model sensitivity analysis process, in order to minimize the  simulation error. The results showed a reasonable match of the runoff changes pattern between the observed and simulated. So that relatively high values of coefficients of determination (R2=0.73) and Nash-Sutcliffe (0.53) during calibration, validation, indicated the model efficiency to simulating common and minimal flow. The results, showed some changes in the average annual rate SIMHYD, +23 to +58 percent that the highest increase rate in October and November and the largest decline in July and August in the future years are. The situation of low rainfall months will be shift to more drought and rainy months toward the flooding.