High vulnerability yet strong resilience of China's lakes to drought

Lakes play a crucial role in the global hydrological cycle and biogeochemical cycle. In China, lakes are an important part of water resources, providing 40.6% of drinking water. In recent years, droughts in the middle and lower reaches of the Yangtze River in China have led to a significant shrinkage of important freshwater lakes, such as Dongting Lake and Poyang Lake, posing a threat to local water security. However, there has been limited research on the extent to which thousands of lakes across China are affected by droughts. This study used remote sensing product of lake area to comprehensively investigate the impact of drought on the area of 4,702 lakes (natural lakes and reservoirs) in China from 1985 to 2018, covering the three stages of response, shrinkage, and recovery. The results indicate that lakes in China are highly vulnerable to drought. The average response probability of lakes is 72.8%, which typically occurs within six months to two years after the onset of drought. The shrinking area of the lake is 12.7% of the original area, and the shrinking process takes an average of 14 months. Lakes also show a strong resilience to drought, with 95.7% of lakes more likely to experience an increase in area following drought-induced shrinkage. However, only 49.4% of lakes are more likely to grow beyond their pre-shrinkage levels. Compared to natural lakes, artificial reservoirs exhibit a higher response probability by 4.6%, a larger shrinkage area percentage by 1.2%, and a higher recovery probability by 2.9%. Consequently, artificial reservoirs exhibit greater vulnerability and resilience to drought, reflecting the impact of human activities. Furthermore, the spatial distribution of vulnerability and resilience is inconsistent. In Northeast China, including the Songhua and Liaohe river basins, and the Mongolian endorheic basin, lakes exhibit higher vulnerability but lower resilience. Therefore, this region is considered a hotspot where the impact of drought on lake area is particularly severe. This study is expected to provide a basis for the implementation of sustainable water resource management and effective drought mitigation measures in China.