Study On The Effect Of Underlying Surface Change On City Waterlogging

At present, China’s urbanization rate has reached 52%～53%, according to the experience of developed countries, the accelerated development ofcity is during the period of urbanization rate between 30%-70%, which means China will be in the stage of rapid urbanization during a long time. The most prominent feature of the development of urbanization is the change of underlying surface. City underlying surface change results in the difference of water cycle between urban and suburban area, and also change regional secondary circulation conditions, which has a close contact with urban waterlogging.City waterlogging is the phenomenon when part of the regional water rainfall intensity is over city drainage and storage water retention capacity. In recent years, waterlogging has intensified the trend, the first and second tier cities and provincial capital cities have frequent waterlogging. Under suchcircumstences, this paper focuse on waterlogging, and choose the effect of underlying surface change on city waterlogging as a research topic.Causes of waterlogging in city include many aspects such as climate, location, surface drainage system etc, this paper analyzes thesespecifically, focusing on the concepts of urban water logging drainage system, rain water pipe design canal reproduce, waterlogging waterlogging control design return period and waterlogging waterlogging legal standard system.The prevention and control of city waterlogging measures are divided into two types of engineering and non-engineering according to whether to change flow condition.This paper analyzes two kinds of measures.This paper expands systematic analysis of waterlogging analysis model containing three parts of runoff, surface convergence, network convergence, and two kinds of methods of hydrology and water dynamics, which is the theoretical foundation for the research model.Selecting Bengbu City as the research object,we establish the analysis model.Using SCS as runoff hydrological model, through the analysis of soil and surface materials,we devivded land use types into six types, which contain 2006 land use object 516 and 2014 land use object 595.The urban flood analysis system was constructed by SCS runoff model,2-D unsteady flow confluence model and simplified drainage model.We calculated for 20 years, 50 years and 100 years return period under the condition of rainfall of urban water situation, compared and analyzed the influence of the change of underlying surface on waterlogging.We carry on the concept of sponge city, introduce the specific details of measures of low impact development, select rainwater storage tank and green roof as LID design, and add them to the model.By calculating the model, the results were compared.