Annual variation characteristics of eutrophication in Dongting Lake, China

The seasonal variation characteristics of eutrophication based on HJ-1 data and synchronous observation data on the ground were studied to provide a theoretical basis for the restoration and management of eutrophication in Dongting Lake. The remote sensing model of chlorophyll-a concentration inversion was established through the comparative analysis of the linear model, exponential model, logarithmic model and quadratic polynomial model by 38 kinds of band combinations. The average relative error was 22.81%. The RMSE of 13.71 mg/m³ was far lower than the average concentration of 34.16 mg/m³. The results showed the following. (i) From the perspective of time distribution, the eutrophication degree decreased successively in summer, autumn, spring, and winter. Dongting Lake is mainly in the state of moderate nutrition, which may be attributed to its unique hydrological conditions (short water cycle and fast flow rate). (ii) Eutrophicated water bodies are mainly distributed in the East Dongting Lake and inner lake where the water flow is relatively slow. The water bodies with pool nutrient status are mainly distributed in the outer lake areas where the water flows faster, such as West Dongting Lake.