Spatiotemporal monitoring of droughts in Iran using remote-sensing indices

Abstract

This study monitored spatially drought in Iran country using distance measurement indicators.Five drought indicators measured from 2016 to 2020 were used: temperature condition index (TCI), vegetation condition index (VCI), vegetation health index (VHI), precipitation condition index (PCI), and standardized precipitation index (SPI). The TCI revealed that the largest percentage of the region classified as "severe drought" occurred in 2020. The VCI indicated that the largest portion of the country (73.30%) experiencing "moderate drought" occurred in 2018.The VHI indicated that vegetation stress increased throughout the region, and areas of severe and moderate drought reached their greatest extents in the mentioned years. Although significant droughts have occurred primarily in the central, eastern, and southeastern parts of Iran, mild droughts have occurred in northern Iran as well. The PCI indicated that rainfall amounts have diminished in most of the country during the period of study. The SPI showed that northern Iran received heavy rain, and was the only region classified as "extremely wet." Most of the rest of Iran were "moderately dry." The analysis of the VHI index for agricultural plants showed that 27.71% of Iran's agricultural regions experienced "critical drought" conditions, this included the provinces of Razavi Khorasan, Hamadan, and Khozestan. The study can provide a baseline for the selection of the most useful drought-monitoring indicators and can enable a deeper understanding of drought in arid and semi-arid regions.