Spatial and Temporal Distribution of Sand Mining in Poyang Lake and Its Impact on Lake Basin Morphology Based on Remote Sensing Images

In this study, by using Landsat satellite remote sensing data and hydrological data statistics, we summarized the spatial and temporal distribution pattern of sand extracting vessels in Poyang Lake from 1999 to 2021, and analyzed the impacts of sand extracting activities on the hydrological sediment balance of Poyang Lake, as well as on the changes of lake basin morphology. Methodologically, the study adopts black and white images in the mid-infrared band for sand mining vessel extraction, and combines the enhanced water body index (EWI) to highlight the water-land boundary, and then superimposes the change of lake basin morphology during the dry water period. The results show that: ① sand mining vessels were mainly distributed in the north lake part of Poyang Lake from 2000 to 2006, and the number of sand mining vessels plummeted in 2008 due to the impact of the banning policy, and 2016 was the peak of sand mining activities, in which the policy regulation is the main factor for the change of spatio-temporal distribution and number and scale of sand mining vessels in Poyang Lake from 2000 to 2021; ② the human sand mining activities have affected to a certain extent the hydrological sediment balance of Poyang Lake to a certain extent; ③ sand mining activities led to a decrease in the beach area in the inlet channel of Poyang Lake and Songmen Mountain area, while the net increase in the beach area in the southeast area of Tangyin was about 7.95 km², mainly due to siltation caused by the spreading of sediments from inlet tributaries of the lake. This study not only assesses the effectiveness of the regulation of sand mining activities in Poyang Lake in recent years, but also provides a reference for the regulation of sand mining activities in similar waters and the assessment of its effectiveness.