关键词: 洞庭湖, 自然灾害, 洪涝, 生态系统, 减灾, 流域管理, 生态工程, 生物量, 滨海湿地, 柽柳, 碳储量

Abstract: Dongting Lake, a lake-reservoir characterized by flood course, receives water from rivers of Xiangjiang, Zishui, Yuanshui, Lishui and a part of Yangtze, and inflows into Yangtze River.In the development of the Dongting Lake region, the environmental management and ecological construction were neglected, the relationships between mankind and land and between mankind and lake were not soundly harmonized, the soil and water erosion in the upper and middle reaches of Yangtze River was aggravated, the sediment deposited in lakes, the lands at lake marshes were excessively reclaimed, and the cropping system at high water level zones was irrational.Consequently, the flood-regulating capacity was descending, the level and the duration of flooding were raised and prolonged, the protective embankments were high and fields were low, the flooding happened out the protective embankments and the fields waterlogged, the frequency of disasters enlarged, and the damage increased.To prevent and fight against floods, the protective embankments were constructed more and more highly, emerging vicious circle of “flood raising embankment leveling-flood re-raising-embankment re leveling”, making flood level go up and flood duration lengthen, and decreasing the draining ability of waterlogged fields.According to the principle of harmonious development between mankind and nature, six ecological strategies for reducing disasters and watershed management were put forward.

Key words: Dongting Lake, Natural disaster, Flooding and waterlogging, Ecosystem, Disaster relief, Watershed management, Ecological engineering, carbon storage, biomass, Tamarix chinensis, coastal wetland