Landsat observations reveal Lake Poyang shrinkage over the past 30 Years: Possible association with local climate change and upstream dam construction

Lake Poyang and its upstream hydrographic network Lake Poyang plays a critical role in freshwater supply, flood regulation, and ecosystem maintenance. However, it has experienced increasing freshwater resource scarcity in recent decades. Understanding the spatiotemporal dynamics of lake inundation and its driving forces is therefore essential. This study develops a deep learning-based identification framework that integrates a knowledge-guided adaptive fusion network with probability mapping. Using batch-processed Landsat imagery from 1994 to 2023 on the Google Earth Engine platform, lake inundation was mapped and temporal trends were analysed. The results reveal pronounced interannual and seasonal fluctuations in Lake Poyang’s inundation extent. Both the yearly mean and yearly minimum inundated areas exhibit statistically significant declining trends over the past 30 years (−16.43 km 2 /yr and −21.51 km 2 /yr, respectively). Causal analyses highlight the influence of local climatic conditions and upstream hydrological changes across multiple temporal scales. The findings offer a novel method for attributing freshwater resource change and caution against attributing Lake Poyang’s shrinkage solely to either local climate change or upstream dam construction. • Landsat-derived lake inundation area is applied to quantify freshwater resources. • Yearly and yearly minimum inundations of Lake Poyang display declining trends. • Simply blaming Lake Poyang shrinkage on upstream dam construction should be avoided.