Revegetation-induced drought propagation shifts prolong hydrological drought recovery on the Loess Plateau, China

Given the inadequate focus on vegetation’s regulatory role in drought propagation, the neglect of differences among vegetation types in mediating drought cascades, and the lack of attention to hydrological drought recovery dynamics, this study targeted three watersheds (Dali, Xinshui, and Yan rivers) on the Loess Plateau, China. This region serves as an ideal study area for exploring vegetation-hydrological drought interactions owing to the implementation of the large-scale “Grain for Green Program (GPP)” in 1999, which has drastically altered the regional vegetation cover and created unique conditions for investigating vegetation-driven drought propagation shifts. By analyzing spatiotemporal changes in distinct vegetation types, key hydro-meteorological variables, and drought propagation patterns over the period 1961–2021, the impacts of vegetation restoration on the meteorological-hydrological drought cascade were investigated, as well as the recovery process and water shortage intensity during hydrological droughts. Results showed that: ( i ) the combined effects of vegetation restoration and climate change altered hydrological processes after 1999 for the GPP. Enhanced vegetation interception and evapotranspiration and aggravated scale mismatch trend to weaken the correlation between SSI, with potential decoupling observed at longer time scales (e.g., 9-months). Hydrological droughts including duration, severity, recovery time and water shortage show an overall worsening trend. ( ii ) The gradual widening of the gap between precipitation and potential evapotranspiration exacerbates the intensity of water shortage during hydrological droughts. This study clarifies vegetation restoration’s drought regulatory mechanism, notes its ecological benefits paired with higher hydrological drought risks, and supports coordinated eco-restoration and water management in semi-arid regions.