Study On The Urban Rainfall Flood Model In Central District Of Shanghai

Presently, the cities are developing fast in china. The urbanization level will achieve 45% by estimated to 2010, and it might enhance to 75% by the middle period of this century, while some city such as Shanghai will be higher. The development also intensely changes the underlying surface in city, thereby affects the characteristic of the ground runoff formation and flow concentration. On the other hand, it is difficult to simulate the under-drainage pipe network in city .Nowadays there are many urban rainfall flood models overseas, however, the harsh suitable conditions restrict the popularize in China. It is of importance and urgent to develop the rainfall flood models which suitable our cities in China.An extensive literature review is done for the research progress of urban rainfall flood, the effect on urban rainfall flood by urbanization and the actuality of urban drainage pipeline. The basis and technical route of the paper is summarized.First, the ground runoff formation and flow concentration. The basic theory is outlined that the rainfall intensity, the soil moisture content, the ground cover and the water-proof area proportion affect the ground runoff formation primarily, and the primary factor affected the surface runoff are the rainfall intensity, the rainfall pattern, the ground gradient of slope and the ground roughness. The underlying surface has been divided into non-permeable layer and permeable layer. The abstraction loss of the former mainly consider depression storage , but the latter should also should add infiltration loss. The methods of flow concentration mainly contain the instantaneous unit line, the contour of equal travel time, the nonlinear reservoir.Second, the computation of pipeline drainage. Saint Venant system of equation is deduced which is on the base of equation of continuity and energy equation. Dispersed nonlinear-kinematic wave equation and solved finite-differential equation by Newton iteration method.Third, the city rainfall flood model is applied to simulate the 2005 "Maisha Typhoon" rainstorm in Xuhui District, Shanghai. The first simulation result is not ideal because of the unreasonable parameters. The second simulation based on adjustment of parameters has been conformed that the result is in accord with the actual inundation data. Simultaneously, some measures of the different seeper places has been suggested.Finally, a summary is given and some problems to be further studied are discussed.