Lake Water Storage and Long-Term Variation of Nganga Rinco on the Tibetan Plateau Revealed by ICESat-2 and Satellite Imagery

Lake storage in Nganga Rinco serves as a crucial indicator of climate change and is significant for the ecological environment. This study combines ICESat-2, the Global Surface Water Dataset (GSWD), and geographic interpolation to derive lake bathymetry and assess 30-year water storage variation of Nganga Rinco. Bathymetry in dynamic regions offers higher spatial resolution and more precise elevation data compared to the SRTM DEM. When compared to in-situ bathymetry, the derived bathymetry showed an average error of 3.64 m, with errors concentrated in deeper regions. The underwater elevation of Nganga Rinco ranges from 4,628.18 m to 4,718.87 m, with an average of 4,698.62 m, showing a total depth variation of 90.69 m. The lake's volume grew from 11.23 km3 in 1992 to 12.06 km3 in 2021, peaking at 12.16 km3 in 2020, reflecting an overall fluctuation increase of 0.82 km3 (7%). Gray Relation Analysis (GRA) was applied to examine how water storage responds to climate change factors. The analysis revealed that precipitation significantly impacts water storage capacity, while air temperature indirectly affects storage changes through snow/ice melting and evapotranspiration. This research offers valuable insights into lake storage estimation in regions that have no direct underwater terrain measurements, providing important implications for water resource management and advancing our understanding of climate change impacts on high-altitude lakes.