Forty-year water body changes in Poyang Lake and the ecological impacts based on Landsat and HJ-1 A/B observations

•The annual means value of the water area and water volume of Poyang Lake exhibit overall decreasing trends.•The water volume is affected by seasonal changes in precipitation and the Project of the Three Gorges Dam in the Yangtze River.•A larger water volume will lead to a decrease in the NH3-N concentration, but reduce the habitats of migratory birds habitats.