Risk Assessment Of Rainstorm Waterlogging Based On Scenario Simulation In Cities

Under the situation of climate change and fast urbanization, the risk of waterlogging is getting greater. Therefore, it is of great significance to carry out waterlogging risk assessment for promoting the harmony between human being and nature, and providing scientific basis for waterlogging risk anagement, contingency plans and sustainable development of shanghai.This dissertation was supported by the National Natural Science Foundation of China (No.40730526, No.40571006) and Shanghai Science and Technology Venus Project (No.09QA1401800). This paper systematically analyzed the formation mechanism of waterlogging, and then established a rainstorm waterlogging model basing on the SWMM hydrologic model. Combining with natural disaster risk assessment theory, a risk assessment on roads and traffic was carried out in different scenarios. Some main conclusions are obtained listed below.(1) Basing on the overview of the drainage system models home and abroad, the profiles and calculation principle of the SWMM model has been systematically summarized. With the analysis on the process and methods of risk assessment, the index system method basing on the scenario simulation in a small scale was initially issued in the field of risk assessment.(2) Using the data of topography, land use, drainage network and etc., the urban rainstorm waterlogging model fit to Shanghai was established by basic data import, watershed classification, parameter estimation and calibration. Four Chicago rainfall scenarios have been synthesized according to the Shanghai storm intensity formula, from which the rainstorm waterlogging in four scenarios was simulated by the SWMM model. The simulation showed that with the increase of the return period, the number of puddles grew quickly, the peak time of the waterlogging came earlier, the duration of the waterlogging lasted longer, and the average water depth increased significantly. In addition, the peak flow of runoff and total flow increased respectively. All these results revealed that waterlogging disasters would be further aggravated. (3) Using the urban road network as the hazard affected body, take scenario simulation as a base, the index system including indicators such as water depth, duration, traffic flow and traffic speed was screened out. The results showed that wanterlogging was extremely serious in Pu Shan and Hua Chang drainage area due to low-lying. As a result, Yong xing Road, Xu jia zhai Road, Yu ying tang Road, Xin road, Xin ma Road, Jingjiang Road were in a high-risk status in four scenarios. Around the study area, the drainage pump played an important role in reducing the risk of storm caused waterlogging. The Pan Jiawan Road, Da tong Road, Bai lu Road, Seven pu Road, Hua xing Road, Shan xi North Road, Zha pu, Hai nan Road, Bei hai ning Road,Yu hang Road and other Roads were in low-risk.(4) On the basis of waterlogging risk assessment, several risk management measures and suggestions such as improving urban drainage systems designing, drainage system maintainence and etc.have been proposed basing on the theory of risk precaution.