基于MIKE模型的极端降雨情景下流域城市内涝风险评估

Urban Waterlogging Risk Assessment in a Watershed under Extreme Rainfall Scenario Based on MIKE Model

由极端暴雨引起的城市洪涝灾害往往具有突发性强的特点,使得城市洪涝灾害的防控极具挑战性。本文利用MIKE FLOOD洪水模拟软件来构建流域城市雨洪模型,将一维河网模块MIKE 11与二维地表径流模块MIKE 21动态耦合,以降雨历时4 h,重现期为20a、50a、100a一遇的降雨过程为边界条件进行模拟,得到不同降雨条件下研究区的淹没情况。以积水深度为评估指标,划分了内涝风险区域等级(内涝无风险、低风险、中风险、高风险区域)。结果发现:本耦合模型适用于城市内涝风险评估管理,动态耦合模拟效果较好,结果与实际发生及调查情况基本吻合;随着新兴流域城市化不断发展,建筑密度越来越大,下垫面硬化率逐年提高,雨水下渗率逐年降低,排水管网负荷越来越大,旧的排水管网系统很难满足现在多数新兴城市排水需求。本研究旨在为极端气候影响下的城市安全防控方案的制定,建立快速准确的风险防控体系和防洪排涝规划、洪涝预警、抢险救灾等提供决策依据。

Urban flood disasters caused by extreme rainstorm are often characterized by sudden intensity, which makes the prevention and control of urban flood disasters extremely challenging. This study uses MIKE FLOOD flood simulation software to construct the urban rainwater model, dynamic coupling the one-dimensional river network module MIKE 11 with the two-dimensional surface runoff module MIKE 21, and uses the MIKE FLOOD model to stimulate the inundation status in Xifeng area separately when it encountered rainfall duration 4 h, the return periods of 20 a, 50 a, 100 a to gain inundation status under different rainfall conditions in the study area. Taking the depth of waterlogging as the evaluation index, the waterlogging risk areas were classified as waterlogging risk-free, low risk, medium risk and high risk areas. The research results show that the dynamic coupling simulation effect is good, the results are basically consistent with the actual occurrence and investigation, and the coupling model is suitable for urban waterlogging risk assessment management;with the continuous development of basin urbaniza-tion, the building density increases, the hardening rate increases, the rainwater infiltration rate decreases, the load of drainage pipe network is increasing year by year, and the old drainage pipe network system is difficult to meet the current urban drainage demands. This study aims to provide decision-making basis for the formulation of urban safety prevention and control programs under the influence of extreme climate, to establish a rapid and accurate risk prevention and control system, flood control and drainage planning, flood warning, and emergency rescue and relief.