Monitoring of the Poyang Lake area’s sharp change under extreme drought using multi-temporal SAR and optical data

In 2022, Poyang Lake in China suffered the most severe drought since records began in 1961, with water levels dropping to historic lows and the lake’s surface area significantly reduced. Given the rapid change of lake water body area under extreme drought, accurate drought monitoring and water body dynamics tracking are important for watershed disaster mitigation and water resource management strategies, whereas traditional remote sensing methods are limited by cloud cover and variable weather. This study addresses these challenges by combining multi-source remote sensing data such as multi-temporal synthetic aperture radar and optical data, using the water index method to achieve dynamic tracking of rapid changes in the water body area of Poyang Lake, analyzing the relationship between the water body area and the water level during the drought period, and combining the data on temperature and precipitation to reveal the intrinsic causes of the drought. The main conclusions are as follows: (1) From July to December 2022, the water body area of Poyang Lake changed rapidly, the water level was at a record low, and the water body area decreased sharply from late July to mid-August and then dropped to the lowest area of 637.05 km2 at the end of September, which was 19.31% of the original one, and then recovered after the drought eased at the beginning of December. (2) There is a strong positive correlation between the water body area of Poyang Lake and the water level of Xingzi, Hukou, Duchang, Kanshan, and other hydrological stations, and the R2 values are 0.9736, 0.9707, 0.9736, respectively, which show high correlation. (3) The drought is mainly affected by the subtropical high-pressure system, which leads to persistent high temperatures and low rainfall, and it has significant meaning to the study of hydrological dynamics of the lakes and climate change.