Combined multivariate drought index for drought assessment in China from 2003 to 2020.

Drought as a complex natural hazard encompassing comprehensive information on the occurrence and development of drought using a single variable alone is difficult. In the present study, a composite multivariate drought index (CMDI) was developed based on a copula combining three univariate drought indices (standardized precipitation index [SPI], standardized runoff index [SRI], and water storage deficit index [WSDI]) and four timescales (monthly, quarterly, semi-annually, and annually). The new index combines information on terrestrial water storage, precipitation, and runoff to capture drought comprehensively. Based on the CMDI, drought trends and characteristics were assessed for 10 major basins in China from 2003 to 2020 using the seasonal Mann–Kendall test and the run theory. The results showed that the developed CMDI 1) integrated meteorological and hydrological drought information using the SPI, SRI, and WSDI; 2) captured overall drought development more completely and frequently than traditional drought indices; and 3) monitored an increasing trend of drought in the Qinghai-Tibet Plateau and North China Plain, in addition to a more substantial drought in northern China than in southern China. [Display omitted] • We developed Combined Multivariate Drought Index (CMDI). • CMDI monitors drought from multiple time scales and factors. • CMDI allows robust and reliable drought characterization. [ABSTRACT FROM AUTHOR]