City Summer Rainstorm Waterlogging Risk Analysis Based On The Community

Since the United Nation passed the A/RES/60/1953Resolution onGeneral Assembly, the decade of International Disaster Reductionstarted from1990. All the member states have signed another vitalagreement on the World Disaster Reduction Conference: the HyogoFramework for Action (HFA). As the guiding principle, the HFA threw thelight on the Disaster Reduction work and practices all over the world. In2010, right after the review and retrospect of5years achievement ofHFA, there is a need of an institutional change from the old Top-bottomway, which means the policy-making level down to the neighborhood,to the Bottom-up way, which means from the neighborhood up to thepolicy-making level. This renovation means more focus on the realsituation on the local level, and accumulates “local knowledge” andbring it to promote the policy making. In this way, the work of DisasterReduction would be more effective and practical.Located in the fluvial plain of Yangtze estuary delta, Shanghai isexposed to typhoon and plum rain, with the strong convective weatherin summer, there is a great amount of rainfall in Shanghai. In Shanghaiarea, there are a lot of neighborhood composed with many agedmultiple-layers public houses in the downtown area that have notconverted yet, which is called “Lao Cheng Xiang”. Compared with thesurroundings, lately renovated infrastructures and newly launchedneighborhoods, such Lao Cheng Xiang kind of neighborhoods arebecoming relatively low in elevation. Considering the fact that theaged drainage facilities are less functional, Lao Cheng Xiang styleneighborhoods are easily exposed to the waterlogging after intenserain during summer.A typical Lao Cheng Xiang style neighborhood in the south-westdowntown Shanghai has been chosen as study region, which is the Jin Sha neighborhood. And this paper focuses on the waterloggingproblems brought by intense rain in summer. The data and informationhave been collected by the way of several times on-site studies andP-GIS based multiple level surveys: the elevation data, attributions ofbuildings (structure, age of the building, location, and function, etc.),the gender and age ratio of the residences, the awareness of disasterprevention and preparedness of local residence, and the disasterresponse skills, etc. Introduced the evaluation method based on CDRIcriteria.Calculated the amount of the rain in given retrace period using theempirical formula of Shanghai rainfall, and calculated the water depthin the area based on the DEM. Then conduct the risk analysis ofwaterlogging in the neighborhood with the “Local Knowledge”, Afterthat, building up the3D scenario model via the GIS tech and Googleapplications (Google Sketchup). Also, shared the study findings andsolutions with the neighborhood through workshop, and trained theresidences of proper DRR skills.This study has completely practiced the method ofCommunity-based Disaster Risk Analysis, so that the study case tailoredaccording to the Lao Cheng Xiang style neighborhood in Shanghaiwould inspires more in the future.