University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 53 6 2022 08 23 Spatio- Decade analysis of Iranian droughts to environmental decision-making Spatio- Decade analysis of Iranian droughts to environmental decision-making 1315 1330 90253 10.22059/ijswr.2022.342456.669258 FA Mahmud Ahmadi Department of Climatology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran Muhammad Kamangar Department of Geography, Faculty of Humanities, Zanjan University Journal Article 2022 05 02 Global warming have led to an increase in the frequency of severe weather events, including droughts. Monitoring and predicting spatio-temporal behavior phenomenon is very important to prevent negative socio-economic consequences and environmental planning. There has been no comprehensive long-term assessment of drought spatial analysis for Iran. For this purpose, first a decade of droughts with the PDSI index from 1980 to 2020 were extracted and then analyzed spatially. The results showed that the intensity of Palmer drought index in Iran increased from -2.12 to 1.45 to -5.73 to 1.34 and changed from dry to extremely dry.The elliptical direction showed three standard deviations in each of the four decades studied northwest and southeast, which was in the direction of unevenness, following the direction of Iran's rainfall. In order to clarify the type of spatial pattern, the G-Star clustering index was calculated and the results showed that in the first decade of the interval, hot spots (severe drought clustering) were found in small parts of the center of Iran and on low rainfall provinces and deserts. Second, hot spots in the southwest of Iran, including Bushehr and Khuzestan provinces, located in the third decade in many parts of the center of Iran, including Tehran, Semnan, Isfahan, Fars, Kohkiloyeh and Boyer Ahmad provinces, and in the fourth decade, hot spots in the south and southeast of Iran. including Hormozgan province and Sistan Baluchistan showed itself as meaningful cluster patterns.The spatial distribution of drought intensities indicates the displacement and intensity of rainfall systems over the decades, indicating that all parts of the country may be at risk of drought. Such research can identify areas at high drought risk and be used in environmental planning. Global warming have led to an increase in the frequency of severe weather events, including droughts. Monitoring and predicting spatio-temporal behavior phenomenon is very important to prevent negative socio-economic consequences and environmental planning. There has been no comprehensive long-term assessment of drought spatial analysis for Iran. For this purpose, first a decade of droughts with the PDSI index from 1980 to 2020 were extracted and then analyzed spatially. The results showed that the intensity of Palmer drought index in Iran increased from -2.12 to 1.45 to -5.73 to 1.34 and changed from dry to extremely dry.The elliptical direction showed three standard deviations in each of the four decades studied northwest and southeast, which was in the direction of unevenness, following the direction of Iran's rainfall. In order to clarify the type of spatial pattern, the G-Star clustering index was calculated and the results showed that in the first decade of the interval, hot spots (severe drought clustering) were found in small parts of the center of Iran and on low rainfall provinces and deserts. Second, hot spots in the southwest of Iran, including Bushehr and Khuzestan provinces, located in the third decade in many parts of the center of Iran, including Tehran, Semnan, Isfahan, Fars, Kohkiloyeh and Boyer Ahmad provinces, and in the fourth decade, hot spots in the south and southeast of Iran. including Hormozgan province and Sistan Baluchistan showed itself as meaningful cluster patterns.The spatial distribution of drought intensities indicates the displacement and intensity of rainfall systems over the decades, indicating that all parts of the country may be at risk of drought. Such research can identify areas at high drought risk and be used in environmental planning. https://ijswr.ut.ac.ir/article_90253_3fbba106470a80993e0bc327f319ac62.pdf