Extent, frequency and duration of lake water level fluctuations (WLF) are dominant forces controlling the functioning of lake ecosystems, especially in the lake's littoral and aquatic-terrestrial interface processes. In East Dongting Lake, Carex life history synchronize the arrival of overwintering birds, Carex meadow provide vital wintering ground for migratory waterbirds, especially for the Lesser White-fronted Geese. However, significant changes had taken place in the hydrological regime of East Dongting Lake and our research showed it caused chiefly by sediment deposition in the lake basin and the replenishment of the Three Gorges Dam. The annual lowest water level of the East Dongting Lake had gradually risen and the annual water level amplitude had decreased obviously over the past 60 years. Since the operation of the Three Gorges Dam, the average water level increased significantly from January to June. The Three Gorges Dam holder the incoming water from late September to late October that the status will change from flood control limited water level to normal water level, meanwhile the water level of East Dongting Lake declined significantly through the same duration, especially in October. The operation of the Three Gorges Dam decreased flooding days in the areas above 22-m elevation, resulting in lowering of the minimum elevation of vegetation-covered area and synchronous downward movement of vegetation distribution pattern. As the timing of water level recession at elevations of 24–27 m were 12, 17, 19 and 16 days earlier than that in 1981–2002, the optimum elevation for Carex growth decreased from 25–26 m to 24–25 m. After the operation of the Three Gorges Dam, the annual reversal times of water level increased significantly, which is not conducive to the formation of stable habitat and the utilization of resources by organisms.

湖泊水位波动（WLF）的程度，频率和持续时间是控制湖泊生态系统功能的主要力量，尤其是在湖泊的沿海和水陆界面过程中。在东洞庭湖，Carex的生活史与越冬鸟类Carex的到来同步草甸为迁徙的水鸟，尤其是小白额雁提供了重要的越冬场所。然而，东洞庭湖的水文状况发生了重大变化，我们的研究表明，它主要是由湖盆中的沉积物沉积和三峡大坝的补给引起的。在过去的60年中，东洞庭湖的年最低水位逐​​渐升高，年水位幅值明显下降。自三峡大坝运行以来，从一月到六月，平均水位明显增加。三峡大坝持有人从9月下旬到10月下旬的进水状态将从防洪限制水位变为正常水位，与此同时，东洞庭湖的水位在同一时期显着下降，尤其是在十月份。三峡大坝的运行减少了海拔22米以上地区的洪水天数，从而降低了植被覆盖区的最低海拔高度，并使植被分布格局同步下降。由于海拔24-27 m的水位下降时间比1981-2002年提前了12、17、19和16天，因此最佳水位苔草生长从25–26 m减少到24–25 m。三峡大坝运行后，每年的水位逆转次数明显增加，不利于形成稳定的生境和生物利用资源。