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Significant changes in snow, glaciers, and the water system across High Mountain Asia (HMA) under global warming have intensified regional water system instabilities. Accurate mapping of the spatial distribution and connectivity of rivers and lakes is essential for understanding and managing the regional water balance and ecosystems. However, existing surface-water datasets lack clear distinctions and connectivity information between flowing rivers and lakes. In this study, three vector datasets over the HMA were developed—Rivers, Lakes, and River–Lake spatial Connectivity—based on the European Space Agency’s (ESA) WorldCover data and the 2020 Global Surface Water dataset from the European Commission’s Joint Research Centre (JRC). Rivers and lakes were extracted separately using Geographic Information System tools for all basins in the HMA and incorporated into a surface water time series. The analysis results showed that the total area of rivers and lakes in the HMA increased by 23.5% from 2000 to 2019, with lakes accounting for 78.3% of this expansion, while river areas expanded by 40.8%. Glacier-fed rivers and lakes contributed 75.5% of the total water area increase, although non-glacier-fed waters exhibited higher relative growth (44.8%) than glacier-fed ones (20.4%). In the endorheic basins, a consistent annual increase in lake area from 2000 to 2019 was observed: the area of hydrologically connected lakes and rivers expanded from 20,782 km2 to 25,396 km2. In contrast, the area of the isolated lakes grew from 9,550 km2 to 12,970 km2. Statistical analysis revealed a significant correlation between the lake area expansion and precipitation. The datasets developed in this study provide the fundamental basis for analyzing changes in rivers and lakes in the HMA, along with their connectivity, supporting regional water resource management, ecological conservation, and sustainable agricultural and pastoral development.
Wang et al. (Fri,) studied this question.