Drought trends projection under future climate change scenarios for Iran region

compared to other scenarios, which is in line with the current investigation. Although in some investigations like [21], an increased precipitation under the B1 scenario compared to other scenarios has been reported, it should be mentioned that the time scale is different in this study. Moreover, since the changes of both precipitation and PET are taken into account for calculating SPEI, the interpretation of SPEI can be distinct from precipitation. In parallel with results of the B1 and A1B scenarios, the most frequency of dry months is observed in Shiraz with 22.63percent, while this value for the B1 and A1B scenarios are 19.70 and 21.16 percent (Tables 4 and 5). 1.23percent of months in Bandarabbas expected to experi- ence extreme droughts, which can be labeled as the driest station throughout the next years. This result matches with the survey of [37]. Due to the proportion of dry months, it can be inferred that approximately over 16.42 percent of months of each station will be experiencing droughts during the next years, which is alarming for Iran. Although the number of months with extreme droughts is much more than other categories, it should be declared that losses and damages of extreme intensity droughts are dramatically more destructive than others. In other words, a short-time drought period with extreme intensity can have long-term repercussions. The highest figure of humid months under the A2 scenario belongs to Ghazvin with 19.93percent, which is similar to the results of the A1B scenario. It is prominent that for all the

stations, the number of months with moderate wet is significantly more than the cumulative amount of extreme and severe wets. The highest number of months with extreme wet is related to Bosheher with 2.30 percent. For examining the changes in the trend of SPEI over the studied period from 2011 to 2112, the results of Mann-Kendall test (Z) are provided in Fig 4. The aim of this test is to statistically evaluate if there is a monotonic increase or decrease trend of the studied variables over the time. It is noticeable that Z�|1.96| refers to the significance level 0.05, while Z�|2.58| implies to the significance level 0.01. Fig 4 indicates that there is a downward trend in the SPEI changes in all the stations, except Esfahan under the B1 scenario. In other words, the value of SPEI over time will decrease Fig 4. The result of Mann-Kendall test on SPEI trend over the whole period. https://doi.org/10.1371/journal.pone.0290698.g004 PLOS ONE Drought trends projection under future climate change scenarios for Iran region PLOS ONE | https://doi.org/10.1371/journal.pone.0290698 November 9, 2023 18 / 24