Analysis of spatiotemporal change characteristics of Poyang Lake from 1984 to 2021 based on GEE.

This study analyzed of spatiotemporal change characteristics of Poyang Lake from 1984 to 2021 by the dataset of Landsat series of satellite imagery and JRC Global Surface Water based on the Google Earth Engine platform. The normalized difference water index combined with the Otsu method was used to extract the water area. The results indicated that from 1984 to 2021, the interannual variation of Poyang Lake's water area presented the characteristics of "fluctuation decline-fluctuation rise-overall decline-overall increase". Additionally, the lake areas in Yongxiu, Xinjian, Nanchang, and Poyang were the primary regions contributing to Poyang Lake's overall area changes. The seasonal variation of Poyang Lake is obvious in a year, the area in summer was larger than that in winter. Compared with 1984, 0.03% of the water area of Poyang Lake in 2021 disappeared permanently, and 8.45% of the water area changed from permanent to seasonal. Lake area changes were jointly driven by climate change and human activities. The average annual temperature increases, agricultural irrigation, reclamation of surrounding lakes and water conservancy engineering caused the reduction in lake area. Increased annual precipitation and the implementation of environmental protection policies were the main factors for the increases in lake area.