Abstract: Due to human activities and climate change, the hydrological regime of Poyang Lake has undergone significant changes. Understanding the variation in its water storage is of great significance for the comprehensive utilization of water resources in the basin. In this study, we used the Google Earth Engine (GEE) platform to analyze the long-term monthly trends of lake area changes from 2003 to 2020 and combined them with measured water levels to estimate the variation in water storage of Poyang Lake. We also calculated the variation in terrestrial water storage in the lake area using the GRACE Mascon product data and analyzed the relationship between the variation in lake water storage and terrestrial water storage. The results showed that the long-term trends in the extracted lake area based on the GEE platform and the variation in terrestrial water storage retrieved from GRACE data were consistent with the measured water level changes at the Xingzi station. Remote sensing images indicated that the water body area in the southern part of the lake changed slightly, and the area with perennial water expanded. The GRACE data also manifested that the average terrestrial water storage in the south part was slightly higher than that in the north. The consistency between the abrupt change points in the variation of terrestrial water storage and the water level at Xingzi station was confirmed by a change point analysis. Wavelet analysis revealed a significant correlation between the variation in lake water storage calculated using the volume method and the variation in terrestrial water storage. Moreover, the variation in lake water storage had a significant impact on the variation in terrestrial water storage of Poyang Lake.

Key words: terrestrial water storage, lake water storage, GRACE, GEE, wavelet analysis, Poyang Lake