With global warming and aggravation due to human activities, many lakes on Earth are facing a series of worsening environmental problems, such as shrinking areas and declining water quality. Poyang Lake is the largest freshwater lake in China, an important wetland in the world and the largest migratory bird habitat in Asia. The ecological environment of the lake has a widespread influence and has attracted international attention. It is necessary to use long-term frequent satellite observations to investigate the Poyang Lake due to its high-frequency fluctuations characteristics. However, most remote sensing data cover only a short period of time, which cannot reflect the long-term change to the Poyang Lake water, no satellite mission currently fits such requirements. Based on HJ-1A/B and Landsat data from 1989 to 2018, the dynamic changes in water quantity in Poyang Lake are monitored in this paper, and the influencing factors and ecological impacts of the changes are analyzed. The results show that in terms of the water area change trend, on the annual scale, the annual mean values of water area and water volume exhibit overall decreasing trends. The water area was the largest in 1998 at 4068.33 km(2) and smallest in 2014 at 899.68 km(2); the water volume was largest in 1992 at 25,810 million m(3) and smallest in 2014 at 5880 million m(3). On the monthly scale, the water area was the smallest in January, largest in July, and showed an increasing trend from January to July; subsequently, a decreasing trend was observed from August to January. The water volume was smallest in February, largest in July, and showed an increasing trend from February to July; then, a decreasing trend was observed from August to February. The water volume of Poyang Lake is affected by seasonal changes in precipitation, and the correlation coefficient between monthly precipitation and monthly water volume is 0.603 (P < 0.05). In summer, the water volume is affected by the water level in the Yangtze River; the construction of the Three Gorges Dam in the Yangtze River caused a prolonged duration of the low water period and an advanced low water period, which are also important factors affecting the water volume change. In terms of the impact of water volume on ecology, the relationship between water volume and NH3-N concentration is obvious, with a correlation coefficient of - 0.679 (P < 0.01). A large water volume will increase the lake water level, reduce the habitats for migratory birds, and provide food to fewer migratory birds.
JOURNAL OF HYDROLOGY 卷: 589 文献号: 125161 出版年: 2020