Climate Change and Variability Impact in Basin's Runoff with Interference of Tow Hydrology Models Uncertainty

Development of greenhouse gases in future periods not only causes change in average amounts of climate variables but also makes variables of this variability affected. Then for sure concerning alternations followed with climate variables’ fluctuations and its average amounts in effecting on runoff would make more reliable results. In this inquiry initially fluctuations and average amounts of climate variables of Gharesuo basin were simulated by HadCM3-A2 model and Statistical Downscaling method in 2040-2069 periods. Although to mention climate fluctuation’s uncertainty in calculations, they acted to simulate 100 time series of temperature and precipitation variables for future period. Results showed that uncertainty confine of region’s climate fluctuations has increased 0.5 to 2C° in temperature and 10 to 20mm changing in precipitation in different months of year. After that and to mention Hydrology model’s uncertainty, two rainfall-runoff models of SIMHYD and IHACRES are used. These two models calibration for base period and introducing 100 time series of climate variables produced in last level into both models specified the basin runoff’s changing confine for 2040-2069 period. Results declare the coordination of two models in region’s runoff changes. As both models estimate runoff abatement for fall season and enlargement for other seasons. Finally the results of this inquiry estate the effect of hydrology model’s uncertainty and less effect of climate variability in estimating a basin’s runoff under impact of climate change.