Increasing sediment flux from rivers in High Mountain Asia poses regional risks

The flux of sediments from rivers in High Mountain Asia – crucial lifelines for one-third of the world’s population – have increased substantially over the past 60 years and are poised to increase further still, a new study shows. These changes, a response to a warmer and wetter climate, have far-reaching implications for the region’s hydropower, food, and environmental security. High Mountain Asia (HMA) – the Tibetan Plateau and the surrounding high Asian mountains – is Earth’s third-largest ice reservoir and the origin of many of Asia’s large rivers. Rivers originating in HMA are now experiencing amplified climate change, glacier melt, and permafrost thaw. These changes are projected to alter sediment fluxes across HMA, which could in turn impact hydropower generation and development, as well as water quality, and also the energy, food, and environmental security of the region. Dongfeng Li et al. investigated the impacts of the changing hydrology on fluvial sediment fluxes in the region over six decades. They present observations of runoff and sediment flux for 28 headwater river basins. These analyses show that rivers that originate in the HMA have experienced large increases in runoff and sediment fluxes in the last 60 years, most dramatically since the mid-1990s. The authors project that sediment flux from the same rivers could more than double by 2050 in the case of extreme climate change. “This study sheds light on the importance and potential implications of the marked increases in recent and future sediment fluxes that have not been fully recognized by scientific communities,” the authors say.