Spatiotemporal evolution and driving factors of Dongting Lake’s water extent based on long-term remote sensing data

Using Landsat imagery from 2005 to 2015, this study employed the Modified Normalized Difference Water Index (MNDWI) to delineate surface water dynamics of Dongting Lake and assess their spatiotemporal evolution and driving mechanisms. The findings indicate that: (ⅰ) The flood season water extent declined from approximately 1,350 km² to 1,110 km². Among the sub-lakes, East Dongting exhibited the highest variability, South Dongting moderate fluctuations, and West Dongting remained comparatively stable. (ⅱ) The mean expansion rates were −9.15, −17.11, and +2.13 km² per year for East, South, and West Dongting, with corresponding change ratios of −1.34%, −3.17%, and +1.61%. (ⅲ) Hydrometeorological variations mainly precipitation and inflow governed seasonal changes, while urbanization, agricultural reclamation, and hydraulic regulation further amplified waterbody shrinkage.