Quantifying the Morphological Evolution of Shallow-Water Lakes Using a Volume Change Model: A Case Study of Poyang Lake

Reliable quantification of morphological evolution in shallow-water lakes constitutes a long-standing challenge for limnological studies, which is essential to advance sustainable lake-basin management. Poyang Lake is a typical shallow-water lake, featuring a basin composed of narrow channels and extensive shallow bottomlands. This geomorphological feature leads to a variety of eco-environmental problems. Using the Google Earth Engine (GEE) platform and field-measured water level data, this study constructed a volume change model (VCM) to estimate changes in water storage (volume) across water levels ranging from 8 m to 14 m in Poyang Lake during 1989–2025. In the VCM, annual surface water areas at the two characteristic water levels (8 m and 14 m, approximating the 25th and 75th percentiles of the long-term water-level record) were first derived. Thus, the volume changes reflect lake-basin morphological change rather than hydrological variability. The results show that lake volume (8–14 m) decreased by 2515.5 × 104 m3 over 1989–2025, an equivalent of 3018.6 × 104 t sediment for the lake basin material. Specifically, the lake basin experienced deposition (1092.0 × 104 t), erosion (2052.0 × 104 t) and deposition (3984.0 × 104 t) during 1989–1999, 1999–2007 and 2007–2025, respectively. The volume change model can effectively quantify lake volume change. Intense basin-wide precipitation led to net sediment deposition during 1989–1999, while large-scale unregulated sand mining operations were closely associated with an increase in the lake volume in 1999–2007. Since 2007, enforced sand-mining regulations have greatly reduced in-lake sand extraction. The sediment input change and sand-mining regulations lead to net sediment accumulation across the Poyang Lake basin.