| Natural disaster is the hotspot question in international society and academe. Heavy rain caused waterlogging disasters in the city has become increasingly. It not only increases the task of flood control and drainage of the city, but also greatly affected economic development and people's lives. Coastal cities are important areas and strategic focus of people convergency, national economy and society development. Therefore, natural disasters have affected more in downtown. In recent years, Tianjin downtown storm frequency increased significantly, with adverse drainage, land subsidence and other factors, waterlogging losses increased. The research of waterlogging disaster simulation, risk analysis, zoning and management will provide theoretical foundation and scientific basis for developing a comprehensive disaster prevention and reduction mode and making contingency plans in the region.This dissertation was financially supported by the National Natural Science Foundation of China(No.40730526, No.40571006 and No.70703010).Based on the analysis of precipitation characteristics and flood and drought characteristics of Tianjin downtown, using hydrological models, compiler in the GIS environment and develop interpolation and rainstorm flooded simulation plugins. Based on scenario simulation, did risk analysis and regionalization for Tianjin downtown waterlogging and proposed waterlogging disaster risk management measures.Several main conclusions are shown as follows:(1)Down town is the area which occurs the most severe floods and droughts in history in Tianjin. The average precipitation rules of each month in central city are as follows:accounting for 71.5% of the total precipitation, summer has the maximum precipitation. In summer, the precipitation in July is the most, followed by August. July and August is the peak of the year, which has the most precipitation. The precipitation decreased gradually forwards and backwards the peak. The precipitation peak appeared in summer, and floods are more easily happened in this season. (2)Different interpolation methods are used with different properties data. Because of the precipitation data is heavily affected by spatial factor, OK is the best method for precipitation data of Tianjin. The distribution of the rainstorm appeared a decreasing from north to south in the central area of Tianjin. The biggest precipitation district presented in northern of Ziya River and Xinkai River, and decreased southward, and the smallest precipitation district appears in the southwest.(3)Distributed the scenario simulation results in the spatial, I got the submerged area map of downtown. Under three kinds frequency of rainstorm, in 2010 the percentage of flooded area are 19.43%,28.97% and 34.08%,estimated affected population are 218000,350700 and 401000. In 2020 the percentage of flooded area are 13.22%,20.30% and 22.53%, estimated affected population are 82000,198000 and 233000. Under the planning condition flood area reduced by 6.2%,8.13% and 11.55%.(4)At a frequency of 3.3% of the rainfall, high-risk drainage area does not exist. Most areas are low risk. At a frequency of 1%,most areas are also low risk. Medium risk area increased 5 ones and none high-risk area appear. At a frequency of 0.2%, the location of risk areas are not changed, medium risk area increased 1,the other two medium risk areas upgrade to high risk area.(5)According to risk division of current conditions,which high-risk area corresponding to the main land use types are towns and villages, residential areas and industrial storage, so engineering measures that drainage, water storage and sedimentation should be control as a priority. Non-engineering measures that change the layout,early warning and social security should be control as a priority. According to the strategic planning of downtown, key development areas are distributed along the Hai River. We should though increasing flood drainage capacity of rivers to ensure the risk of waterlogging is minimum. |
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