Spatiotemporal variations and drivers of runoff in China based on a high-quality continuous runoff dataset

Study region: China. Study focus: Hydrometric gauge networks across China provide inadequate records for comprehensive natural runoff monitoring. Here, we utilized the China Natural Runoff Dataset, a high-quality, continuous runoff dataset, to elucidate the spatiotemporal variations and key drivers of runoff across China from 1982 to 2015. New hydrological insights for the region: We identified a distinct southeast-to-northwest gradient in runoff distribution. Significant runoff increases in northwest China and declines in central China have collectively shifted the runoff gravity center northwestward. Multiple linear regression analysis reveals that precipitation is the dominant driver of runoff variations across 90 % of the country, with high coefficients of determination (R2 > 0.4, p < 0.05). Significant positive correlations between runoff and precipitation are observed across all river basins, with correlation coefficients ranging from 0.77 to 0.95 (p < 0.05). Vegetation cover and air temperature are the leading factors that influence runoff both positively and negatively in 5.5 % and 4.5 % of the grids, respectively, mainly in the Continental River basin (CRB) and the Yellow River basin (YRB). In CRB, rising temperatures may increase evaporation and exacerbate soil moisture deficits, leading to reduced runoff, or alternatively may enhance glacial snowmelt and thereby increase runoff. In YRB, human-driven vegetation restoration efforts around 2000 significantly reduced runoff, whereas notable increases in runoff post-2000 are likely attributed to substantial rises in precipitation.