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• Extreme drought decreased the water area and quantity of Poyang Lake by 78.4% and 90.63%. • Lake shoreline decreased by 2923.70 km and morphometric indices varied greatly affected by drought. • Drought event changed water quality by meteorology, water–rock interaction and human activities. Extreme drought poses a significant threat to humanity. In the summer of 2022, the world experienced the worst drought in recent years, with a precipitation deficit and an abnormal high temperature, profoundly affecting human life and the aquatic environment. However, the drought influence on large freshwater lakes remains unclear. In this study, we selected China’s largest freshwater lake (Poyang Lake) as the research object and investigated the lake water area, quantity, lake morphology and water quality in 2018 (normal season) and 2022 (extreme drought period). Results showed that standardized precipitation index (SPI), standardized runoff index (SRI) and standardized precipitation-evapotranspiration index (SPEI) reached moderate to severe drought in the summer of 2022. From 2018 to 2022, lake water area decreased (1789.62 km 2 ), water quantity reduced (15.40 × 10 9 m 3 ) and lake shoreline decreased (2923.70 km). The shoreline development index, size ratio and energy factor decreased by 4.87, 198.53 m and 963.60, specifically. The dynamic ratio, relative depth and Schindler’s ratio increased by 1457.10, 0.04 and 13.48 m −1 , respectively. The water chemical indicators varied significantly in two years and the water hydrochemical types changed from SO 4 ·Cl − Ca·Mg type and HCO 3 − Ca·Mg type to SO 4 ·Cl − Ca·Mg type from 2018 to 2022. Water-rock interaction, alternating cation adsorption and anthropogenic influence on water quality represented different patterns in two periods. Our findings demonstrate significant differences in water resources and quality between common and extreme drought conditions in China’s largest fresh water lake, which can inform research on climate change effects on international large freshwater lakes.
Wang et al. (Fri,) studied this question.