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Many high-mountain rivers in Asia transport more sediment downstream compared to a few years ago. Changes in sediment levels have a particularly strong impact on agriculture, water quality, flood management, and hydropower generation.

A with participation from the University of Potsdam demonstrates the interacting roles of glaciers, vegetation, precipitation, and slope in mobilizing sediment and controlling the current sediment transport in rivers. In order to counteract climate change, the authors call for a systematic approach for the entire catchment area of rivers in the high mountains.

"The specific sediment yield in catchments with high glacial cover is on average an order of magnitude higher than glacier-free basins, and appears higher overall in Asia's glacierized catchments than those reported for the European Alps, the Andes, or Norway," says Bodo Bookhagen, professor for Geological Remote Sensing at the University of Potsdam.

The fluvial suspended sediment threatens the water quality downstream and thus the aquatic ecosystems, the river infrastructure such as hydropower plants and bridges, as well as agriculture and pastoralism.

The team investigated 151 rivers around the Tibetan plateau and demonstrated that glaciers exert a first-order control on fluvial sediment yield, especially with high precipitation and in high glacier-cover basins.

"Our work highlights the many competing factors in controlling the transported material in river catchments and shows that a more accurate prediction of the sediment volume should consider not only climate change, but also glacier dynamics and vegetation changes and their interactions with slope," Bookhagen says.

Vegetation influences sediment transport especially in the Eastern Tibetan Plateau and Tien Shan. Depending on the climate zone, vegetation can either promote erosion of material or have a stabilizing effect on slopes. These findings call for a systematic basin-wide approach to climate change adaptation in high mountain regions.