Urban Storm Water Risk Analysis

Located in the fluvial plain of Yangtze estuary delta, Shanghai is exposed to typhoon and plum rain, with the strong convective weather in summer, Shanghai has a great amount of rainfall. In Shanghai area, there is a lot of old public house in the old urban renewal that has not converted yet. Compared with the new buildings, old house's relative relief is low, and the drainage facilities are aged, so these areas are easily influenced by the storm water. This paper choose one small region to research senario-based rainfall water disaster risk spatial distribution.On the base of systematically analysis of international and national disaster risk assessment's research progress, tish paper developed senario on the amount of precipitation, takes the area of Putuo District Jisha neighborhood committee as example, carries out a given probability-based rainfall risk assessment, find the amount of people affected, using the amount to express the affect of the waterlogging by storm. The paper aims to provide a solid theoretical basis for government to reduce disaster and draw up contigency planning.Tish paper use the empirical formula of Shanghai rainfall to calculate the amount of the rain in given retrace period. Combined with the DEM to calculate the water depth in the area. Then according to the houses' height above ground to distribute the houses being affected by waterlogging. Using the information of the population in the area, calculate the affected popolation, using the amount of people to express the affect of the given senario. Finally, this paper analyses the hazards factors briefly, and raises some regional stragedies proposals.The main conclusions are as followings: (1)In the senario of return period of 50 years, when the drainage system runs good, the max water depth in the area is 0.273m, the population being affected by submerging is 1304, the population being affected by transportation difficulties is 3712; when the drainage system runs general, the max water depth in the area is 0.295m, the population being affected by submerging is 1618, the population being affected by transportation difficulties is 4180; when the drainage system is out of order, the max water depth in the area is 0.346m, the population being affected by submerging is 2324, the population being affected by transportation difficulties is 5167.(2)In the senario of return period of 100 years, when the drainage system runs good, the max water depth in the area is 0.311m, the population being affected by submerging is 1883, the population being affected by transportation difficulties is 4788; when the drainage system runs general, the max water depth in the area is 0.329m, the population being affected by submerging is 1887, the population being affected by transportation difficulties is 4788; when the drainage system is out of order, the max water depth in the area is 0.376m, the population being affected by submerging is 2617, the population being affected by transportation difficulties is 5167.(3)In the senario of return period of 500 years, when the drainage system runs good, the max water depth in the area is 0.343m, the population being affected by submerging is 2324, the population being affected by transportation difficulties is 5167; when the drainage system runs general, the max water depth in the area is 0.359m, the population being affected by submerging is 2358, the population being affected by transportation difficulties is 5167; when the drainage system is out of order, the max water depth in the area is 0.405m, the population being affected by submerging is 3170, the population being affected by transportation difficulties is 5725.(4)We found that the running condition of drainage system has a great influence in the rainfall waterlogging disaster risk, the importance of the drainage system is no less than the rainfall.