| Taihu Lake basin is one of the regions in China where water resources has been highly integrated used. Our government has paid great attention to its comprehensive regulation and The State Planning Commission approved the "the Comprehensive Regulation Planning Scheme for Taihu Lake Basin" in June 1987. Flood prevention and water logging control are the major objectives of the scheme, water supply, navigation and environment protection are considered as well. The plans will be carried out in different stages, which involves 11 key projects, including: Taipu River, Wangyu River, dyke around the Taihu Lake, south-drainage in Hangjiahu plain, water drainage and diversion in Huxi, Hongqitong, flood control in east-west Tiaoxi, water drainage and diversion in Wuchengxi, enlarging Lanlugang, dredging Liuhe and Xietang, north drainage in Hangjiahu, and flood prevention in the upper stream of Huangpu River.In recent years, with the development of economy in the Taihu Lake district, human activities have caused serious impact on the eco-environment and the land cover condition, which intensify the water pollution of the basin. At the same time, water demands of industry and agriculture as well as water supply in cities are increasing year by year. Ground water overdraft leads to the continuing subsidence of part plain surface. Large quantity of water use as well the deterioration of water quality in rivers and lakes result in regional water resources shortage in dry years, on the other hand, regional water logging and flood disasters frequently occur in plenty water years. Water resources problems have constrained the social and economic development in this region.Taihu Lake basin is a plain water network district where water flows are very complicated. In addition, water control projects such as gates, pumps, polders and dikes spread all over the basin. All these bring more difficulties to scheme making for flood broadcasting and prevention as well as disaster reduction. On the basis of the existing whole basin water quantity model, this paper further expanded and improved the function of the water quantity model HOHY2 used by the Taihu Lake Authority. At the same time, the flood forecasting and regulation system suitable for Taihu Lake basin has been established, which provides support for sustainable use of water resources and social-economical development in the basin.The main research contents of the paper involve: establishment of real time forecasting system of Taihu Lake basin; forecasting method for the tidal levels along Yangtze River and Hongzhou Bay; model mechanics of flow generation and confluence forecasting; forecasting model mechanics of flow dynamics in plain river networks of Taihu Lake basin; case study of real time flood forecasting and control in Taihu Lake basin.The main features in the study of flood forecasting and control system are as follows:(1) Runoff generating and confluence theory and hydro-dynamic method are adopted to predict the water level of Taihu Lake and key nodes, the basin wide forecasting and control system with the function of real time correction has been first established in plain river network to meet the complicated flow conditions of Taihu Lake basin and to enhance the reliability offorecasting results;(2) According to the rainfall in foreseen period multiple schemes can be made in the forecasting model and adjusted with time, which overcomes the errors caused by the uncertain rainfall in the foreseen period so as to make the forecasting results approach reality. The system possesses the real time correcting function, which can avoid error accumulation and highly increase the forecasting accuracy;(3) The flood control system can be multiple-scheme designed, that is, the control schemes can be designed in terms of different control ways for hydro-projects. Simulated computation can be carried out to obtain multiple schemes that can be used by the leaders for decision making after risk and consequences estimation, so as to scientifically enhance th...
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