Investigation of Changes in the Amount and Distribution of Extreme Precipitation and Its Effect on the Trend of Changes in the NDVI Index Changes in Southeast Iran

This study investigated the effect of extreme precipitation values on the trend of vegetation cover change in southeastern Iran. Extreme precipitation indices were selected using a fixed approach recommended by the Expert Team on Climate Change Detection and Indices, according to local needs and theclimatic characteristics of the study area. These indices were extracted using daily precipitation data from the stations of the study area over a 21 years from 2000 to 2020 utilizing RclimDex software. The NDVI index of MODIS satellite images was used to analyze the trend of annual vegetation cover changes. Also, the multilayer perceptron neural network method was used to examine the relationship between changes in extreme precipitation indices and vegetation cover changes. The results showed that the NDVI index has an increasing trend spatially from the east to the west of the region. Areas with low NDVI were observed in the eastern, southern, and northern parts and areas with high NDVI were observed in the western part of the study area. The trend of NDVI index changes was significant and upward only at Rudan station (P-value = 0.01) and Kahnuj station (P-value = 0.0001). The overall trend indicated an increase in precipitation extremes during the study period. The extreme precipitation indices Rx1, SDII, and PRCPTOT have the most significant on the trend of changes in vegetation cover in the southeastern region of Iran. A comprehensive study of the impact and trend of changes in extreme precipitation indices on vegetation cover in the southeastern region of Iran will lead to the development of sustainable management methods and resilience to climate change.