Study Of The Plan Of Urban Flood Control Of Cities Along The Yangzi River In South Of Giangsu Province

Based on property of water system and hydrology, this paper mainly studies on the hydrological calculation methods for flood prevention of cities along the Yangzi river in south of Giangsu province. The plan of urban flood control of Jiangyin is made in detail.According to the demand of flood prevention, the paper analyses the influence of urbanization on hydrology situations, the property of flood and water-logging, the mechanism of disaster generation, the existing and problems of urban flood prevention in China. Considering the difference of runoff characteristics on different underlying surface in the area of plain tidal river network, four kinds of surface is divided,namely, waters,paddy field,dry land and central urbanized area, and the suitable method is adopted separately in each surface to simulate runoff process. Furthermore, the paper researches runoff calculation of central urbanized area, the underlying surface is divided into pervious and imperviousness areas. In perviousness areas, Hoton Infiltration formula and Corresponding spatial infiltration rate curve are used to establish the relationship between infiltration rate and soil moisture in order to decide the infiltration. The control of urban drainage network is consdidered in the calculation of concentration in urbanized areas. Saint_venant Equations discreted by 4-point Preissmann implicit scheme is used to calculate river flood water level. To solve the node equations, Successive Over Relaxation Method which based on the Matrix Mark Method for solving large size sparsity linear equations is used. At last, river water level in different plan condition is calculated integrating the method of city runoff and river network hydraulics, to provide technical supports for flood-prevention projects, and to analys and evaluate the capability of the flood prevention of cities.The achievements of this paper have provided guidance for the flood prevention plan of Jiangyin City, and the methods suggested here are applicable to other similar hydrological problems of cities in cities along the Yangzi river in south of Giangsu province.