Abstract: Poyang Lake is the largest freshwater lake in China. It is located in the middle and lower reaches of the Yangtze River in the north-central Jiangxi Province. As the largest Lake which is connecting the Yangtze River, the water ecological security of Poyang Lake affects the entire Yangtze River basin. Chlorophyll-a is an important indicator of water ecological eutrophication, so it is of great significance to carry out routine monitoring of chlorophyll-a by remote sensing. In this study, Poyang Lake is taken as the experimental area, and chlorophyll-a, which represents the degree of eutrophication, is taken as the retrieval index, based on the observation data of six years from 2015 to 2020 and Landsat series of images, under the condition of standard modeling phase and "satellite-ground " coordinated matching, the retrieval model of chlorophyll-a in Poyang Lake water body in summer is constructed by analyzing and comparing the correlation index between different wave bands and chlorophyll-a. After verification by six groups of independent data, the mean value of R² is 0.86, the mean value of RSME is 1.01 ug/L, and the mean value of MAPE is 17.6%. It is believed that the method adopted in this study can be better applied to the inversion of chlorophyll-a in Poyang Lake area, and also provides a new reference method for the monitoring of chlorophyll a in inland Class II water bodies with long-term observation conditions.

Key words: remote sensing, Poyang lake, chlorophyll-a