Assessment of Climate Change Impacts on Water Resources in Varamin PlainBasin Using SWAT Model

This study evaluates the effects of climate change on temperature,rainfall,runoff in future periods by LARS-WG statistical model,SWAT hydrological model under A1B,A2,B1 climate scenarios. First,in order to produce future meteorological data,the LARS-WG model was calibrated,the coefficient of variation of minimum temperature,maximum temperature,precipitation for future periods was simulated as SWAT model vertices. The results of the LARS-WG model showed that minimum,maximum temperature will increase in future periods,there will be changes not only in rainfall but also in the rainfall pattern. Then runoff simulation was performed on a monthly basis by the SWAT model. The SWAT-CUP software,the SUFI-2 algorithm were used for calibration,validation. NS,R2coefficient for calibration period were 0.58,0.65,and for validation period were 0.49,0.5. Then,by introducing the average of the results of the SWAT model,the runoff changes from the basin were simulated during the periods 2011-2030,2046-2065,2080-2080. The results showed that runoff in the period of 2011-2030 will increase under all three scenarios in the spring,summer seasons,decrease in autumn,winter seasons. Also,runoff in periods of 2065-2070,2080-2080 will be increased under all three scenarios in autumn,winter,will decrease in spring,summer. This seasonal displacement in runoff is due to the effects of climate change in the form of temperature rise,melting snow,changing rainfall patterns,and so on.