Quantifying multi-sphere impacts on mountain runoff of a Third Pole River

Area of Science:

• Hydrology
• Climate Science
• Environmental Science

Background:

• Mountain runoff is vital for water resources, yet its changes due to multi-sphere interactions are poorly understood.
• Quantifying impacts of atmospheric, glacial, and vegetation changes on mountain hydrology is challenging due to data and methodological limitations.

Purpose of the Study:

• To quantify the impacts of warming, wetting, glacier retreat, and vegetation greening on mountain runoff in the upper Salween River basin.
• To identify the dominant drivers of changes in mountain runoff.

Main Methods:

• Utilized a high-resolution meteorological forcing dataset (TPMFD).
• Employed a physically based cryosphere-hydrology model (WEB-DHM-S).
• Conducted six sensitivity experiments to isolate the effects of different factors on runoff.

Main Results:

• Annual runoff showed a slight, insignificant downward trend (-1.5 mm yr⁻¹) from 1981-2020.
• Warming decreased runoff by 37.5 mm due to increased evapotranspiration; wetting increased runoff by 10.5 mm.
• Glacier retreat (+61.7 mm) and vegetation greening (-9.2 mm) had significant impacts, with combined effects leading to substantial runoff decreases.
• Climate change accounted for 73.3% of runoff changes, while glaciers and vegetation regulated the remaining 26.7%.

Conclusions:

• Climate change (warming and wetting) is the primary driver of mountain runoff changes in the upper Salween River basin.
• Glacier and vegetation dynamics play a crucial regulatory role in modulating runoff responses.
• Findings offer critical insights for water resource management and sustainable development in mountain regions.