I am deeply humbled and honored to have been awarded the prestigious Wang Gungwu Medal and Prize (Best Ph.D. thesis in the Natural Sciences) for my thesis titled “Response of riverine sediment fluxes to climate change in High Mountain Asia and its margins“.
The Wang Gungwu Medal and Prize is a university-level award given to a single recipient in the Natural Sciences and Social Sciences/Humanities at the National University of Singapore each academic year; no award is made unless there is a candidate of sufficient merit.
Thesis abstract: “Rivers originating in High Mountain Asia (HMA), the ‘Asian Water Tower’, are among the planet’s most important river systems for providing resources for approximately 2 billion people. Since the 1950s, the amplified climate change and accelerating glacier-snow melt and permafrost degradation in HMA have affected the seasonal and annual streamflow. However, the response of fluvial sediment fluxes to climatic and cryospheric changes remains poorly understood, although sediments and their associated nutrients, contaminants, and carbon have important implications for hydropower operation, water quality, and riverine carbon cycle. This study holistically addresses this knowledge gap by integrating all the available multi-decadal fluvial sediment flux data in HMA and its margins, examining their temporal trends, investigating and quantifying the driving factors, and assessing their downstream impacts.
The results show that the sediment fluxes in the pristine headwaters of HMA have been increasing substantially over the past six decades in response to the warmer and wetter climate. The sediment fluxes from HMA will likely increase from the present 1.94 ± 0.80 Gt/y to 5.18 ± 1.64 Gt/y by 2050 under an extreme climate change scenario. For typical permafrost-dominated basins like the Tuotuohe headwater, attribution analysis shows that climate warming and accelerating glacier-snow-permafrost melt are the primary cause of the increased sediment fluxes, with precipitation increase being the secondary driver. Air temperature dictates the seasonal sediment dynamics by controlling the active contributing drainage area and multiple thermal erosional processes such as glacier-snow melt and thaw slumps, while rainstorms dictate fluvial extreme events. For the disturbed Jinsha basin at HMA’s margins, cascade reservoirs dominate the changes in the sediment fluxes. This study also concludes that the rising fluvial sediments associated with their carried nutrients, heavy metals, and carbon from HMA can decrease hydropower lifespans, degrade water quality, and increase flooding risk, thus threatening the region’s securities of energy-food-environment.”