Beijing Urban Waterlogging Spatial Distribution Of Research And Risk Analysis

With global warming, the frequency of extreme weather events is improving, the urban waterlogging caused by extreme rainfall occurred frequently over the past decade in major cities of China, which brings serious harm to personal safety and social assets. The "7.21" incident caused71deaths,1.9million people were affected and economic loss were nearly10billion in Beijing2012.The reason caused urban waterlogging has two main factors:heavy rainfall and complex structure of urban surface. Urbanization made the city expands quickly. By effect of "Urban Heat Island", rainfall intensity in city is higher than suburbs. The impervious surface and sunken overpass cause serious waterlogging, and cities’ drainage capacity is low. So, under the effect of natural and urban, waterlogging often happens in summer.Most studies of urban waterlogging are analyzed by model construction, these methods conduct process simulation for local area waterlogging, the spatial-distribution research for entire city is not so much. This paper is based on disaster risk analysis theory, choose Beijing urban as the study object, analysis the mechanism of waterlogging, analyze problems from three aspects:hazard of disaster-inducing factors; sensitivity of disaster-inducing environment; vulnerability of hazard-affected bodies. The main content and conclusion are as below:(1) This paper construct the indicator system of waterlogging risk for Beijing urban, by analyzing the mechanisms with Beijing specific environmental characteristics, we selecte risk-analysis indicators.(2)Then, we collect a variety of spatial and attribute data from internet and related project, using GIS methods to extract spatial-distribution information of the indicators, get spatial distribution map of each index.(3)At last, based on AHP method, we analyze characteristics of Beijing urban waterlogging, determines the weight value of each index, generate waterlogging disaster-risk map by ArcGIS overlay technology. The Ⅶ and Ⅷ level is considered to be high risk areas, count such places’name, we get the waterlogging high-risk areas’ statistical table in different periods of Beijing city. The result can provide scientific basis for the city’s waterlogging disaster prediction.