Explaining the spatial patterns of drought intensities in Iran

 Recognition of spatial patterns of drought plays an important role in monitoring, predicting, confronting, reducing vulnerability, and increasing adaptation to the hazard. The aim of this study is to identify the spatial distribution and analyze the annual, seasonal, and monthly spatial patterns of drought intensities in Iran. For this purpose, drought intensities were extracted from the monthly rainfall reanalysis data (ERA5) of the European center Medium-range Weather Forecast (ECMWF) for the period 1979-2021 and the ZSI index. Achieving the research goal and explaining the spatial pattern governing the frequency of drought intensities (extreme, severe, moderate, and weak), spatial statistical methods such as global Moran’s index, Anselin local Moran’s Index, and hot spots were used. The results of the global Moran’s index showed that with increasing intensity, the spatial distribution of the drought phenomenon has become clustered. The spatial distribution of the local Moran’s index and hot spots also confirm that. There was high contrast in the local clusters of high (low) occurrence as well as hot (cold) spots of severe (extreme) annual droughts in the south, southeast, and east. In the autumn, weak to extreme droughts have a southeast-northwest direction. But in spring and winter, the spatial pattern of drought is very strong as opposed to severe and moderate drought. Despite the relatively high variability of maximum positive spatial correlation of severe and extreme monthly droughts, their spatial pattern is almost similar. The forming of spatial clusters of severe and extreme droughts in the northwest, northeast, and especially on the Caspian Sea coast, is a serious warning for the management of water resources, In particular for rainfall-based activities, such as agriculture.