Assessing the impact of vegetation changes on water availability in the upper Yellow River Basin, China

Study region: The upper Yellow River Basin (UYRB), China Study focus: The influences of vegetation changes on terrestrial water and energy fluxes have attracted global attention, yet the effect on water availability remains uncertain. In this work, we combined long-term satellite data and ecohydrological modeling to explore how vegetation changes affect hydrological processes and water availability across different climatic conditions and vegetation types in the UYRB, the most important water conservation area within the YRB. The Community Land Model version 4.5 (CLM4.5), coupled with the Variable Infiltration Capacity (VIC) parameterizations, was utilized for ecohydrological applications. New hydrological insights for the region: From 1982 to 2018, vegetation in the UYRB exhibited a predominantly greening trend, with 57.9 % of the area showing significant greening, resulting in increased evapotranspiration (ET), diminished runoff, drier soil conditions, and decline in water yield and terrestrial water storage change (TWSC). According to the simulation using the satellite-derived dynamic leaf area index (LAI), we further estimated that a unit change in LAI resulted in changes in water yield and TWSC of-124.15 f 71.38 mm yr-1 and-102.21 f 74.98 mm yr-1, respectively. However, the simulation with model-predicted LAI underestimated this control, likely due to the poor representation of LAI dynamics. The LAI effects were significantly modulated by climatic conditions and vegetation types, with the greening of vegetation exacerbating water scarcity in arid regions.