Projecting drought trends and hot spots across Iran

The frequency and severity of extreme climatic phenomena, including droughts, have increased across the globe. The aim of this study is to detect changes in the severity and trends of short- and medium- term droughts (3 and 12 months) across Iran (1990-2019) and project the near (2059-2030) and far (2095-2066) future changes. SPI and SPEI indices were used for this purpose. The non-parametric Mann-Kendall test was used for trend analysis, and the G * (Geties and Ord) index was exerted for hot spot analysis. The results revealed that in 1990-2020, except for 3 month SPI (SPI3) index, the SPI and SPEI trends tended to be negative and statistically significant at the 0.05 significance level. During the same period, specified and significant hot spots of the indices were formed in the northern and northwestern Iran, and significant cold spots were concentrated only in Zabol and Birjand stations in eastern Iran. Near and far future minimum and maximum monthly precipitation projections for four selected stations show increases in monthly maximum and minimum temperatures and decreases in precipitation at all stations, though the decrease in precipitation for Esfahan station only with RCP8.5. The Projected trends of 3 and 12 months SPI and SPEI (SPI3, SPI12, SPEI3 and SPEI12) in near and far future show the dominance of significant negative trends. Projected trends of SPI and SPEI for the near future was negative for all stations, though it was positive and significant for far future.