Drought assessment and development trend in Mu Us Sandy Land based on standardized precipitation and potential evapotranspiration index

• The multi-scale drought index is calculated from high quality climate data. • The drought trend was analyzed by improved M−K test. • The temporal and spatial characteristics of drought are based on EOF analysis. • Multi-threshold operating theory is used to identify drought events. • Drought prediction based on different emission scenarios. Global warming leads to more frequent droughts. Therefore, in order to understand the development characteristics of drought, based on high-resolution climate data, the Mann-Kendall test, empirical orthogonal function decomposition and multi-threshold operation theory were adopted to analyze the characteristics of the multi-scale standardized precipitation index (SPI) and the standardized potential evapotranspiration index (SPEI) from 2002 to 2021. Based on CMIP6, the development trend of drought under different emission scenarios from 2021 to 2040 was predicted through multi-model ensemble (MME). The results show that both SPI and SPEI effectively identify the drought conditions in MUSL. The short-term scale (1/3 month) of SPI is stable in identifying drought with precipitation deficiency, and SPEI is more sensitive to sudden drought driven by high temperature. Both indicators on a long-term scale (6/12 months) can effectively monitor persistent drought. In the low-emission scenario (SSP126/245), drought is mainly dominated by precipitation changes. The results of SPI and SPEI are relatively consistent and both can be used for monitoring. In the high-emission scenario (SSP370/585), the increase in temperature intensifies evapotranspiration. SPEI can more accurately reflect the actual drought risk, while relying solely on SPI may underestimate the intensification effect of high temperature on drought. The comprehensive implementation of these measures will effectively enhance the resilience of the study area in responding to the increasingly severe drought challenges.