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Study region The source region of the Yangtze River (SRYR), China. Study focus Under global warming, land surface heatwaves (LSHs) have intensified across the Tibetan Plateau, yet their hydrological impacts in snow-dominated basins remain unclear. Using satellite-derived land surface temperature and observed runoff data, this study characterizes spring LSHs and quantifies their relationships with spring runoff in the SRYR. This analysis focuses on heatwave frequency (HWF), duration (HWD), and intensity (HWI), and their relationships with snow cover fraction (SCF). New hydrological insights for the region Spring LSHs have intensified during 2000–2024, with HWF, HWD, and HWI increasing by 0.09 events, 0.61 days, and 0.47 °C per decade, respectively. Correlation analysis indicates that the relationship between LSHs and runoff strengthens with increasing SCF. Despite this, relationships between LSHs and total spring runoff remain weak at the basin scale. In contrast, the LSHs show more consistent associations with the runoff fraction during the early spring. A 1 °C increase in HWI corresponds to an increase of 1.29% in the early spring runoff fraction, suggesting a tendency toward an approximate shift of 0.12 km³ of runoff from late to early spring. These results suggest that LSHs are more closely related to the timing of spring runoff release rather than the total seasonal runoff amount in snow-dominated mountain basins.
Tian et al. (Fri,) studied this question.