Role and Protection of Dongting Lake

洞庭湖作用与保护研究(英文)

Water and sediment in four-inlet river system and the water level at Chenglingji reflect the current relationship between Yangtze River and Dongting Lake. Since the flow in four-inlet river system is reduced gradually, the lake water level is also reduced, resulting in shrunk lake area, channelized lake, narrowed channel and reduced rfve beach. Facing the changed relationship the River and the Lake after the utilization of Three Gorges Project, the Chenglingji control engineering at the outlet of Dongting Lake and the dredging of four-inlet river system are car- ried out. Thus the roles of flood control （1.67x101~ m3） and water amount regulation （2.3~101~ m3） of Dongting Lake are fully played. The Dongting Lake plays compen- sating and scheduling roles in the flood control and water storage of the Three Gorges Reservoir. It can reduce a volume of 4.0x109 m3 of excess flood around Chenglingji. In addition, it can also provide a water supply of 5 000 m3/s to the lower reaches of Yangtze River during the dry season for about 30 d. The Dongt- ing Lake plays an important role in the stabilization of ecological environment in the watershed, the regional water resources security and the protection of Dongting Lake and Yangtze River.

四口河系水沙和城陵矶水位体现当代江湖关系,因四口河系分流入湖水量不断减小,湖区水位下降,水面萎缩,湖泊河道化、河道洲滩化、洲滩陆地化趋势凸显。为适应三峡工程运用后的江湖关系变化,针对性的采取洞庭湖出口城陵矶控制工程以及四口河系的疏浚措施,充分发挥洞庭湖167亿m3洪水调节容积和2 300亿m3水量的调济作用,对三峡水库防洪和蓄水进行补偿调度,可减少城陵矶附近的超额分洪量40亿m3,可具备枯水期补充长江下游5 000 m3/s 30 d左右的水源,对稳定流域生态环境水域条件、区域水资源安全、以及洞庭湖和长江的保护,均具有十分重要的作用。