城市化的洪灾风险效应及适应性风险管理体系研究

At present, most regions in the world are in the stage of rapid urbanization, which can not only promote the social and economical development, but also have a profound effect on the flood hazard-formative environment. More and more frequent storms and floods, together with highly-concentrated population and assets, will aggravate potential risks of floods, which will pose a serious threat to urban development. Consequently,study on the impacts of urbanization on flood hazard-formative environment, hazard-formative factors and hazard-affected bodies, quantitative evaluation of the effect of urbanization on flood disaster risks, and establishment of flood disaster risk management system suitable to urbanization process are necessary for sustainable urban development. Currently, there is neither reliable method for dynamic evaluation of flood disaster risk in the process of urbanization nor flood disaster risk management system suitable to the characteristics of urbanization. In this proposal, Qinhuaihe river basin in Yangtze River delta will be selected as the research object. Based on the flood disaster formation mechanism, two kinds of models will be built through combination of establishment of flood disaster risk evaluation index system with analytic hierarchy process and combination of hydrologic-hydraulic calculation with flood loss calculation separately, aiming to dynamically evaluate the flood disaster effect in the process of urbanization and to simulate the disaster-reduction effect of suitable countermeasures. Flood disaster risk management system will be established based on the concept of flood disaster risk management corresponding to urban development. This research will provide theoretical basis for the understanding of the effect of urbanization on flood risks, which will be helpful for decision-making on flood prevention and risk-reduction in urbanized regions.

当今世界正处在快速城市化阶段，城市化在促进社会经济发展的同时，也深刻地改变了洪灾的孕灾环境，频繁发生的暴雨和洪水作用于高度密集的人口和资产，加剧了洪灾风险，对城市发展构成严重威胁。所以，研究城市化对洪灾孕灾环境、致灾因子和承灾体的影响，定量评价城市化对洪灾风险的效应，建立适应城市化发展的洪灾风险管理体系，对保障城市可持续发展具有重要意义。但目前还缺乏动态评价城市化洪灾风险效应的方法和针对城市化特点的洪灾风险管理体系。本项目拟选地处长江三角洲的秦淮河流域为研究对象，从洪灾形成机制出发，分别建立风险评价指标体系构建与层次分析相结合、水文水力学计算与淹水损失计算相结合的两种模型，动态评估城市化的洪灾风险效应，并模拟各种适应性措施的减灾效果。基于洪灾风险管理理念建立适应城市化发展的洪灾风险管理体系。该研究可为深入认识城市化影响洪灾风险的机理提供理论依据，为城市化地区防洪减灾提供决策支持。

当前全球许多地区正处在快速城市化阶段，城市化深刻地改变了洪灾的孕灾环境，频繁发生的暴雨和洪水作用于高度密集的人口和资产，加剧了洪灾损失，对城市发展构成严重威胁。洪灾风险的大小与灾源、传播路径、承灾体及采取的对策密切相关，所以，研究城市化对致灾因子、孕灾环境和承灾体的影响，定量评价城市化的洪灾风险效应，建立适应城市化发展的洪灾风险管理体系是非常必要的。本项目选择江苏省秦淮河流域为研究对象，基于HEC-HMS建立了该流域的暴雨洪水模拟模型，保持降雨输入不变，仅改变流域下垫面条件，分析城市化的洪水水文效应，表明随着城市化的发展，流域洪水过程的洪峰流量及洪量均增大；构建了风险评价指标体系，采用层次分析法评估了城市化的洪灾风险效应，表明随着城市化的发展，流域各分区的洪灾危险性、暴露性、风险度均增加，且秦淮河中游区风险增速最快。选择江西省景德镇市为研究对象，构建河道模型、城市洪涝模型、洪灾损失模型，实现“暴雨→洪水→淹没指标→洪灾损失”的递进计算。在保持水文输入、减灾措施相同的情况下，针对现状年和规划2030年两种城市化状态，分别计算淹没指标和洪灾损失，结果表明，在20年一遇频率下后者的总积水面积为前者的2.4倍，洪涝损失为前者的10倍。系统规划了由“水库、堤防、排涝泵站、排水管网”等工程措施和“实时雨洪监测、洪水预报预警、土地利用调整、应急响应、公众参与、法规约束”等非工程措施组成的洪灾风险管理体系。针对五种工况、两种典型洪水、四种设计频率，分别计算了风险管理单项措施或其组合的淹没指标和洪涝损失，表明所构建的洪灾风险管理体系能有效降低洪灾风险。成果可为景德镇城市洪水风险管理提供依据，为类似城市的洪灾风险管理研究提供重要参考。