Prediction of the Impact of Climate Change on Drought During 2011 -2100, Using SPEI Index: A Case Study of Southern Khorasan, Iran

Due to the critical role of water in human life, studying the effects of climate change on the intensity and frequency of drought in order to cope with the phenomenon of climate change is important. This study evaluates the effects of climate change on drought phenomenon in the Southern Khorasan province with using precipitation - evapotranspiration standardized index (SPEI). In this regard, the output of HadCM3 model under four emission scenarios A1, A2, B1 and B2 has been downscaled by IDW method as well as the method of change factor was used to construct a time series of climate scenarios for 30-year periods. Then, the studied index (24-month time scale) was calculated for future periods and probabilities of moderate and severe droughts in various regions of the province were determined. The results indicate the occurrence of severe droughts will be more in the west of the province in the near future and the occurrence of the severe drought will increase in the western and north-eastern areas in the intermediate and distant future, respectively. Furthermore, it is highly probable that the northern half will have the moderate drought in the future periods.