Application of time series Sentinel-1 in drought monitoring of East Dongting Lake in 2022

To accurately monitor the development of drought in the rare and severe drought in the East Dongting Lake area of the Yangtze River Basin in 2022, a rapid extraction model for the water body range in the lake area was established based on open-source Sentinel-1 satellite image data. Using ESA SNAP for batch image preprocessing, and using the Sentinel-1 Dual-Polarized Water Index water index algorithm to extract the water surface range using histogram bimodal threshold segmentation, a long-term spatial dataset of the water surface range of East Dongting Lake is constructed to dynamically evaluate the progress of drought. The results show that this method can accurately extract the water body range in Sentinel-1 images of different periods in the lake area, and intuitively reflect the degree of drought in the lake area. The water area in the lake area rapidly decreased from early July 2022 to the peak of drought by the end of August. From then until the end of October, the water area in the lake area remained at a relatively low level without further drastic reduction, and the drought continued. In early October, there was widespread and large-scale precipitation in the Dongting Lake area, and the drought briefly eased. The research results can provide useful references for drought dynamic monitoring in regional time series.