Assessing vulnerability and population exposed to drought in various climatic regions of northeastern Iran

The motivation of this research is the continuation and intensification of drought effects on various socio-economic sectors and the observation of few studies and no coordinated efforts to provide a compatible framework for drought risk management in different economic sectors and population groups of the study region. Present research was carried out to assess the vulnerability and population exposed to drought in Khorasan Razavi province. Meteorological data sets for the years 1950-2020, drought indices including Palmer self-calibration (scPDSI), standardized precipitation (SPI), standardized precipitation evapotranspiration (SPEI), population and livestock density indicators, agricultural lands, water stress, socio-economic and infrastructural factors have been used. Results indicate that dry and wet periods were estimated more intense by SPEI in all studied stations, also a significant difference was observed between the results of the SPI and SPEI indices in determining the long dry and wet periods. The highest variation between the occurrence of dry and wet periods was estimated using the SPEI, which could be related to seasonal fluctuations of temperature and computational evapotranspiration. Although no significant correlation was observed between used indices to identify the number of wet months, however, a significant positive correlation exists between the numbers of dry months estimated by those. Drought risk analysis demonstrated that the central and southern parts of the province are exposed to very severe drought, while the northern and northeastern parts of the area are more inclined to severe drought. The highest class of drought exposure is observed in the southern, central, and eastern regions of the province so they represent the high-risk category of drought.