Projected changes in extreme precipitation indices over the Lake Urmia basin in Iran

This study investigates the future changes in precipitation extreme indices in the Lake Urmia Basin during the period 2021–2100 compared to the base period (1987–2016), using the Coupled Model Intercomparison Project Phase 5 models. Trend analysis was performed using Mann–Kendall test and Sen's estimator. The output of these models was downscaled by the Long Ashton Research Station Weather Generator method for the representative concentration pathway (RCPs) 4.5 and 8.5. A model averaging technique was employed to create an ensemble model. The results showed that the average precipitation of the basin will decrease by the end of the 21st century. The projection also showed that the consecutive dry day's index increases based on both scenarios. However, other indices (maximum 1-day precipitation, maximum 5-day precipitation, very wet days, consecutive wet days, simple daily intensity index, and wet-day precipitation) are reduced compared to the base period. Moreover, the slope of significant trends in the RCP8.5 is greater and more severe than that in RCP4.5. HIGHLIGHTS This study focuses on the future change of extreme rainfall in the Lake Urmia basin in Iran.; The projected results are decreasing trends in extreme precipitation and in wet days and increasing trends in dry days by the end of the 21st century.; This study predicts that the basin may face more drought in the future.; The results of this study have important implications for the management of water resources.;