Performance Investigation of the climate elasticity method and the model of SIMHYD For quantitative evaluation of the Effective Factors On hydrological drought

Fluctuation in climatic variables and increasing human activities, transformation in hydrological processes and consequently it will follow the destruction of ecosystem structure. Therefore, quantitative evaluation of climate variability and human activity as the main factors influencing the hydrological processes are very important for water resources management and planning and for economic-environmental and sustainable development. The purpose of this study is to analyze the detection of changing point hydro climatic variables in Vasaj watershed in Hamadan, also estimation of the impact of climate change and human activities on the watershed annual discharge. Therefore, hydro climatic series trends and fluctuations during 1393-1366 were investigated Then, SIMHYD hydrological model and climate elasticity method were used for quantitative evaluation of hydrological drought regard to climate variability and human activity. The results showed 7.13% decrease in rainfall, 12.3% increase in evapotranspiration and 83.92% decrease in human activities in the runoff. The contribution of human activity and climate variability in runoff reduction using the elasticity method in two techniques of climate Torque and Zhang were obtained in Torque 84.80 and 15.19 and 19.15, and in Zhang method 84.97 and 15.02, respectively. Hence, human activities is the main factor in runoff production. In addition, hydrological SIMHYD model simulations of discharges was not acceptable. Due to the significant changes in land use, it is considered as one of the most obvious human interference in the watershed. The results showed that the area of orchards and vineyards has increased 15071.4 and 15375.69 ha compared to before the change point respectively.