Rainfall intensity differentiates hydrological functions in alpine permafrost landscapes

Study region The source region of the Shule River, northeastern Tibetan Plateau. Focus of study Identifying how rainfall intensity triggering differentiation of hydrological functions in the representative alpine permafrost landscapes (cold desert, alpine meadow, and alpine shrubland), through field-based monitoring and water balance calculation. New hydrological insights for the region This study demonstrates that rainfall intensity differentiates the hydrological functions of the three alpine landscapes. The cold desert consistently functions as an infiltration‑dominated system, with negligible runoff (runoff coefficient < 0.01) and high infiltration (10.09 ± 1.32 cm/h). In contrast, the alpine meadow exhibits a runoff coefficient that is higher under light rain (0.178) than under moderate rain or heavier rain (P > 10 mm/d) (0.063)—a pattern explained by rainfall duration and activation of preferential flow pathways. The shrubland shows evapotranspiration exceeding precipitation under light rain (ET/P = 1.30). Under moderate, the meadow shifts to substantial soil water storage (ΔSWS = 6.95 mm), the shrubland reaches high ET (6.22 mm), and the cold desert maintains deep percolation. Soil water storage dynamics further support this functional differentiation. These three landscapes exhibit complementary functions: percolation (cold desert), runoff/storage (meadow), and evapotranspiration (shrubland). This study provides a site‑specific analysis of how rainfall intensity differentiates hydrological functions in alpine permafrost landscapes, enhancing understanding of water cycle processes in cold regions.