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An analysis from researchers including USGS reveals potential impacts on water, food, and energy supplies due to rivers’ altered sediment regimes, posing risks to downstream communities.

The analysis, spanning several decades, demonstrates how climate-induced alterations in sediment dynamics are disrupting the seasonal flow of river-borne materials and, consequently, could jeopardize year-round water, food, and energy provisions for downstream communities.  

The study centers on four key cryosphere-fed rivers in high-mountain Asia, each characterized by different regimes of water supply: mostly glacial runoff, mostly snow- and ice-melt, mostly rainfall, and mixed. The cryosphere is the frozen-water component of the environment that includes snow and ice on land, ice caps, glaciers, permafrost, and sea ice. 

Focusing on the period from the 1960s to the 2000s, the study revealed a distinct trend in seasonal sediment-transport regime shifts. During the spring, the study found a notable transition towards rainfall-dominated sediment transport. This shift was attributed to reduced snowfall and an increase in erosive rainfall, marking a significant departure from historical patterns.

Moving into summer, the analysis found intensified glacier meltwater pulses and heightened pluvial (rainfall-influenced) events. These factors contributed to an exceptional surge in sediment fluxes, a shift from previous seasonal patterns.  

The research underscores that hydroclimatic extremes and the degradation of the cryosphere are key drivers behind the amplified variability in water and sediment fluxes. This phenomenon results in higher summer sediment peaks, posing a direct threat to downstream river infrastructure safety (dams and reservoirs) and ecosystems. 

Of particular concern is the potential exacerbation of glacial outburst and pluvial floods, which can have devastating consequences for communities situated downstream. The increased sediment peaks not only compromise the integrity of river infrastructure but also pose a significant risk to ecosystems that depend on the predictable ebb and flow of river dynamics. 

The findings highlight the urgent need for adaptive measures and sustainable management strategies to mitigate the impacts of climate change on cryosphere-fed rivers. As these vital waterways undergo unprecedented shifts in sediment dynamics, downstream communities must prepare for heightened risks to their safety, infrastructure, and essential resources.

Figure showing shifted sediment-transport regimes by climate change and amplified hydrological variability
(A) Cryosphere coverage and decadal hydroclimatic change rates in the glacial basin (Xiehela at Tien Shan), nival basin (Qiaqiga at Tien Shan), pluvial basin (Yingluoxia at Qilian Mountain, north Tibetan Plateau), and mixed-regime basin (Qiemo at Kunlun Mountain, north Tibetan Plateau). Doughnut icons depict the rates of change of hydroclimatic variables, with temperature (red), rainfall (light blue), and relative percentage change rates of snowmelt (violet), RSs (light green), discharge (Q, dark blue) and suspended sediment concentration (SSC, brown), where clockwise denotes positive rates and counterclockwise denotes negative rates. See detailed observation records and the magnitude of trends in tables S1 and S2. (B to E) Monthly patterns of Q and SSC. The shaded area denotes SDs. Gray vertical bars denote spring and autumn. From the study Shifted sediment-transport regimes by climate change and amplified hydrological variability in cryosphere-fed rivers.

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