Effect Of Retreating The Flood Storage In Dongting Lake

The reclamation of Dongting lake has been persisting a long time .sediment aggradation and the exposed shoal make reclamation liable,at the same time productive demand and keeping off schistosomiasis are the dynamic source of reclamation, long-term sediment aggradation and reclamation diminish the area of Dongting lake, in consequence, the flood storage capacity dimmished.and so increase the flood control burden of Dongtinglake and the middle reach of the Yangtze River. Therefore the area of Dongting Lake must be enlarged, retreating the flood storages is one of the most important measures.which has been being studied from 1990's at home .It's has important significance to Dongting lake stabilization,analyzing flood diversion risk and the flood control in the middle reach of the Yangtze River. In this paper,based on the feature of Dongting lake, a model combining Hydrological model with hydraulic model was applied to estimate the efficiency of retreating the flood storages. Simultaneously,this model can asle be applied to flood plain that is big and with more branches,such as Poyang lake ,the middle and the down stream of the Yangtze River.The main works and conclusions were summarized as follows:Chapter 1 has introduced briefly on the function of Dongting lake of regulating and storing of the middle reach of the Yangtze River, some problems and the significance of retreating the flood storages, summarized the current research situation and forefathers' research result of retreating the flood storages, analysed its existing deficiency, established the direction and content of this research. Meanwhile , sumed up the main works and conclusions in this paper.Chapter 2 has analyzed the principle and the effect of retreating the flood storages of Dongting lake, applied one-dimensional numerical model to research the influence facters of the effect of retreating the flood storages, thereof Put forward one's own research method, and made rational generalization scheme to the model.Chapter 3 has set up flood control model of Dongting lake,and tentative to apply the model to calculate the effect of retreating the flood storages, to Dongting Hu prevent flood calculation of effect.the model can calculate the water level and the dicharge anywhere in simulated area,Through increasing the branch ( corresponding different flood storage ), changing valid volume of the storage and the open mode to imitate flat retreat of Dongting lake.Chapter 4 has analyzed the changes of discharge and water level of the lakeregion and the middle reach of the Yangtze River before and after retreating the flood storages under the condition of typical flood, predict the effect of preventing flood .Through change the different effective conservation storage volume of flood storage position of lake region and detention basin to imitate single retreat(people retreat but plow not), and Through change the mode of flood control of different position of lake region to imitate the effect of double retreat(people and plow both retreat),Compare with the different influence of preventing flood of different position to analyse the inherent reason, and put forward the suggestion .the reliability of the model has been tested,it's suitable for the research of retreating the flood storages of huge flood plain.Chapter 5 has sum up the whole paper and prospect further research work.