Global Assessment of Socio-Economic Impacts of Subnational Droughts: A Comparative Analysis of Combined Versus Single Drought Indicators

Abstract. The accurate assessment of the propagation of drought hazards to socio-economic impacts poses a significant challenge and is still less explored. To address this, we analyzed a sub-national disaster dataset called the Geocoded Disaster (GDIS) and evaluated the skills of multiple drought indices to pinpoint drought areas identified by GDIS. For the comparative analysis, a widely used Standardized Precipitation Index (SPI), Normalized Difference Vegetation Index (NDVI), Standardized Soil Moisture Index (SSI), and Standardized Temperature Index (STI) were globally computed at the subnational scale. In addition, we developed a novel Combined Drought Indicator (CDI), which was generated by a weighted average of meteorological and agricultural anomalies. Out of 2142 drought events in 2001–2021 recorded by GDIS, NDVI, SSI, SPI, and STI identified 1867, 1770, 1740, and 1680 drought events, respectively. In terms of the skill to cover GDIS-documented drought events, CDI outperformed the other single-input-based drought indices and identified 1885 events. This emphasizes the importance of using CDI to evaluate socio-economic drought risks and prioritize areas of greater concern.