Evolution characteristics and driving mechanisms of ecological drought from a terrestrial ecosystem perspective

Yellow River Basin (YRB) This study aims to systematically investigate the spatiotemporal evolution patterns and driving mechanisms of ecological drought in the Yellow River Basin (YRB) from 1982 to 2022. A novel Standardized Ecological Water Deficit Index (SEWDI) integrating vegetation dynamics and hydrological processes is developed. Using multi-source data and an integrated methodology including improved run theory, Copula joint probability models, Modified Mann-Kendall method (MMK) trend analysis, and XGBoost-SHAP machine learning framework, the research quantitatively assesses drought characteristics across multiple time scales and identifies key driving factors. A significant basin-wide drying trend (–0.017/10a) with strongest intensification in western upstream regions (–0.043/10a). Distinct westward migration of drought centers, with over 91% of western areas affected in the 2010s. The July 2019–April 2020 event was the most severe on record, peaking in February 2020 with 98.08% of the basin affected, a severity of 9.14, and a 10-month duration. Drought intensification is particularly pronounced in December (Z s = –1.33) and winter (Z s = –1.46), with 97.79% and 94.25% of the basin showing aggravating trends, respectively. Evapotranspiration (ET) emerges as dominant climatic driver, while Atlantic Multidecadal Oscillation (AMO) is primary circulation factor exacerbating drought. These findings provide crucial insights for ecological drought early warning and adaptive water resource management in the YRB. • Ecological drought intensified significantly in the Yellow River Basin (1982–2022). • The most severe drought lasted 10 months and affected 98% of the basin. • Evapotranspiration was the dominant climatic driver of ecological drought. • Atlantic Multidecadal Oscillation primarily exacerbated drought conditions.