Impact of lake inflow and the Yangtze River flow alterations on water levels in Poyang Lake, China

Abstract

As China's largest freshwater lake, Poyang Lake is essential to regional development and global ecological conservation, but its interaction with the Yangtze River complicates prediction of lake level changes. To evaluate potential impacts of lake inflow and the Yangtze River flow alterations caused by climate variability and human activities, a hydrodynamic model that considers river-lake interactions was adopted to compute the specific change of water level and surface area in Poyang Lake corresponding to given lake inflow and/or Yangtze river flow alterations under 3 groups of scenarios. Results indicated that both lake inflow and the Yangtze River flow alterations significantly impact the Poyang Lake level. The lake level was more sensitive to alterations in lake inflow than equivalent alterations from the Yangtze River discharge. Both sources of alterations had respective influences on water level magnitude and pattern due to the discrepancy in hydraulic connectivity between the main waterbodies in the lake. Lake inflow alterations caused approximately uniform water level change in Poyang Lake, while Yangtze River alterations mainly affected the northern lake, especially at low water levels. Consequently, Poyang Lake management should take a basin-scale approach, especially under the new flow regimes in the Yangtze River resulting from the normal operation of the Three Gorges Dam.