Abstract: Investigating erosion and river sediment yield in high-mountain areas is crucial for understanding landscape and biogeochemical responses to environmental change. We compile data on contemporary fluvial suspended sediment yield (SSY) and 12 environmental proxies from 151 rivers in High Mountain Asia surrounding the Tibetan Plateau. We demonstrate that glaciers exert a first-order control on fluvial SSYs, with high precipitation nonlinearly amplifying their role, especially in high–glacier cover basins. We find a bidirectional response to vegetation’s influence on SSY in the Eastern Tibetan Plateau and Tien Shan and identify that the two interacting factors of precipitation and vegetation cover explain 54% of the variability in SSY, reflecting the divergent roles of vegetation in promoting biogenic-weathering versus slope stabilization across bioclimatic zones. The competing interactions between glaciers, ecosystems, and climate in delivering suspended sediment have important implications for predicting carbon and nutrient exports and water quality in response to future climate change. 

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 study with participation of 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 overall higher 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," Bodo Bookhagen emphasizes. 

Vegetation influences sediment transport especially in the Eastern Tibetan Plateau and Tien Shan. Depending on 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.

The observed relationship between SSY and mean annual precipitation conditioned by glacier cover (circle sizes)

The observed relationship between SSY and vegetation cover (NDVI) and precipitation

Source: Dongfeng Li, Ting Zhang, Desmond E. Walling, Stuart Lane, Bodo Bookhagen, Shang Tian, Irina Overeem, Jaia Syvitski, Albert J. Kettner, Edward Park, Michèle Koppes, Rafael J. P. Schmitt, Weiling Sun, Jinren Ni, Todd A. Ehlers. The competing controls of glaciers, precipitation, and vegetation on high-mountain fluvial sediment yields. Science Advances, 2024; 10 (48) DOI: 10.1126/sciadv.ads6196

University of Potsdam. "Swelling streams -- climate change causes more sediment in high-mountain rivers." ScienceDaily. ScienceDaily, 4 December 2024. https://www.sciencedaily.com/releases/2024/12/241204114321.htm