Construction and Application of a Novel C‐Vine Copula‐Based Multi‐Variate Ecological Drought Index

A comprehensive ecological drought index capturing vegetation growth conditions and meteorological–hydrological variability is essential for assessing ecological drought and optimizing water resource management. This study selected soil moisture (SM), actual evapotranspiration (ET), land surface temperature (LST) and leaf area index (LAI) to construct a C‐vine copula‐based multivariate ecological drought index (MVEDI). Using the Lancang‐Mekong River Basin as the study area, this study analysed the capability of MVEDI in characterizing typical drought events and revealed the spatiotemporal evolution characteristics of ecological drought events across the basin. The study area comprises four sub‐zones (Zones I–IV). The results showed that, compared with the standardized soil moisture index (SSMI), standardized evaporative stress index (SESI) and standardized vegetation health index (SVHI), the MVEDI showed the strongest correlation with the standardized solar‐induced chlorophyll fluorescence index (SSIF), with 48% of grid cells exhibiting correlation coefficients greater than 0.4 and better capturing typical drought events. Zone III exhibited the greatest spatial variability in drought severity (1.4–20.2), peak severity (1.02–3.09) and intensity (0.29–1.45), while Zone II had the largest variation in duration (3.7–17 months). The proposed framework and its application evaluation results provide a useful reference for ecological drought monitoring and optimal allocation of water resources in other river basins.