Hydrological Response to Vegetation Changes in the Yellow River Basin

The Yellow River Basin (YRB) is confronted with significant conflicts between water, food, and ecology. A thorough understanding of the human stresses on eco-hydrological processes is essential for the sustainable management of the YRB. To simplify the complex nature-human interaction system, we developed an analysis framework based on vegetation change and the Budyko hypothesis. The intra-annual vegetation change was explored using phenological indicators, in addition to the inter-annual vegetation change represented by annual maximum NDVI. K-means clustering was used to identify seven patterns of vegetation change driven by different ecological projects, agricultural alterations, and climate change. To explore the hydrological responses to environmental changes revealed by vegetation, a distributed attribution analysis of runoff changes was conducted using the ERA5-Land dataset and an elasticity method based on the Budyko hypothesis. The results show that the hydrological-related landscape changed most in the semi-humid and semi-arid areas experiencing revegetation, and the aridity increased most in the upstream and downstream irrigation areas. Human-driven landscape changes contributed to 44.1% - 60.7% of the local runoff reduction within the YRB. Notably, agricultural changes intensified drought, similar to revegetation, and meanwhile, the combined effect of climate change and ecological engineering could magnify agricultural vulnerability. We propose the adoption of drought-tolerant crop planting and water transfer across watersheds to ensure water-food-ecology security.