Research on sustainable strategy for flood defense and mitigation of Dongting Lake

摘要

Due to its special geological and hydrological values, Dongting Lake Played a key role in the flood defense system of Yangtze River in the past hundred years, but the people there who contributed a lot to guarantee the safety of Jingjiang Dyke and the Wuhan City during flood emergency also suffered a lot. The aim of this paper is to develop a sustainable strategy to improve the flood storage capacity of Dongting Lake and minimize the damage of flood, which focuses more on the comprehensive and sustainable future of Dongting Lake than traditional strategies did. By characterizing the relationship between Dongting Lake and Yangtze River and analyzing the most serious floods in this area in 20~(th) century, this paper shows that the Lake is indispensable to the flood defense system of the Yangtze River Basin as a key detention area of extra flood water and will keep this role even after the Three Groges Project puts into operation. Quantitative evaluations on practical or expected performance of both engineering and non-engineering measures are proposed, such as strengthening the dykes, removing polders to transfer flood, enlarging the capacity of the rivers, returning farming lands to lakes, accelerating the construction in the flood diversion and detention areas, improving the arrangement of the flood regulation reservoirs in the downstream areas of the four rivers(Xiangjiang, Zijiang, Yuanjiang and Lishui, Hunan), etc. Evaluations are also achieved on some planned projects, such as the regulation of the Three Gorges Reservoir in light of the water lever of Chenlingji, the Sankou river channel harnessing and the Chenglingji-Hankou river channel harnessing, etc. Finally, this paper presents a novel flood defense-mitigation system with emphasis on the improvements of the relationship between Yangtze River and Dongting Lake, the flood storage capacity, and the standard of dykes.