Assessment of Climate Change Impacts on Drought and Wet Spells in Lake Urmia Basin

Abstract

Drought is recognized as a natural hazard and environmental disaster, and has caused extensive impact worldwide. The increasing frequency and severity of droughts associated with global climate change is an important issue in agriculture and water resources. Given the critical situation of water resources in the Lake Urmia Basin, predicting drought characteristics in future periods is very important in this basin. In this study, to evaluate the future drought and wet spells in Lake Urmia Basin, the daily outputs of the second-generation Canadian Earth System Model (CanESM2) model under RCP2.6, RCP4.5 and RCP8.5 emission scenarios were projected and downscaled using the Statistical Downscaling Model (SDSM) model for two periods, 2031–2050 and 2051–2070. Subsequently, the drought status and its trends in the baseline period (1986–2005) and future periods were investigated using precipitation data and the Standardized Precipitation Index (SPI). Then, the drought and wet spell characteristics including occurrence, persistence and the stationary probability of each class were calculated using the Markov chain model. The results showed that the probability of droughts in the stations of Lake Urmia Basin increased in the future. Also, by increasing SPI timescales, drought persistence increased under all three scenarios. On the other hand, by increasing the SPI timescales, the intensity of droughts and wet spells decreased, while their persistence increased.