Urban Waterlogging Risk Level Assessment Methods And Case Study

In recent years, as urban development speeds up and urbanization continuously progresses, more and more attention is being paid to urban waterlogging hazards under heavy rain conditions caused by undermined water infiltration capacity of hardened underlying surfaces in cities. This paper focuses on waterlogging risk level assessment,and investigates the causes of urban waterlogging through data collection and analysis;by referring to domestic and foreign methods for assessing waterlogging risk levels,analyzes the application conditions for different methods, and through comprehensive comparison of the methods by applying them to the studied area of Baoji City,determines an appropriate method for assessing waterlogging damage and comes up with specific water drainage renovation measures for the studied area based on the assessment results.Main conclusions of this paper include:(1) Study of domestic and foreign methods for assessing waterlogging hazards,including DRI(Disaster Risk Index system), natural disaster assessment models,European multi-risk assessment models, disaster risk management index system, social disaster risk index method, all of which are based on basic assessment indexes such as population and vulnerability of exposed area, disaster-inducing factors, etc. and adopt different formulas to conduct comprehensive assessment. With similar assessment processes, the results differ slightly with different methods.(2) By referring to analysis of waterlogging hydraulic calculation cases based on different waterlogging disaster assessment models and taking inundation analysis as the index, compares the risk level assessment results in the cases, and the comparisonindicates that the inundation level classification standards obtained from different software are varied, so are the risk level assessment results. Judged from the complexity of the case implementation processes and the accuracy of the results,Infor Works, MIKE, SWMM and Digital Water Simulation are more frequently used.(3) For the inundation simulation of the studied area of Baoji City, two methods are utilized, i.e. DigitalWater Simulation and SWMM, and four different methods are used for assessment, which are HR threshold value method, HAZUS theory method,distribution function method and historical similarity method. Through analysis of the inundation results and discussion over the results of four assessment methods, the final conclusion is that the HAZUS theory method which boasts the highest similarity with the actual conditions is the most feasible one, and under the premise of a perfectly matched database, it can represent the real-life risk assessment results. This method has been utilized to carry out renovation of the studied area, and the result turned out to be satisfactory.