城市暴雨洪涝灾害的气候变化响应与风险评估研究

Recent rainfall induced flood events in urban areas have greatly raised the awareness of both policy makers and academic researchers the needs for managing urban flood risks, the damage of which is often significantly higher than rural areas. Building upon our strong record in urban natural hazards studies and previous NSF projects, in this proposal, we aim to investigate the future rainfall induced flood risks in urban areas, in response to potential climate change, using Shanghai as a case study. We seek to use the state-of-art combination of: (i) climate downscaling of future precipitation; (ii) numerical modelling of rainfall induced flood risks; and (iii) field survey of present/future vulnerability for key receptors. A widely-used statistical modelling tool SDSM-DC, developed by CI Wilby in Loughborough, will be used to generate future climate change scenarios at a regional/city level. Instead of simply producing future scenarios, we will use SDSM-DC to evaluate adaptation decisions and the sensitivity of the system to climate change. This will be evaluated for the 2020s, 2030s and 2050s. High-resolution historical data collected at 10 meteorologic stations in Shanghai (1981-2010) will be used. With the input from climate downscaling, using a scenario-based approach, future flood inundation will be modelled using a well-established flood modelling tool FloodMap, developed by CI Yu. A high resolution approach will be used to undertake urban flood modelling, coupling sewer flow and urban flood inundation. Future vulnerability will be assessed based on questionnaire survey and field investigation. This will build upon the previous studies by the PI and her team. A spatiotemporal approach will be used in the analysis of risks, aiming to demonstrate the evolution of flood risks over time and space for various receptors. A framework for assessing future urban flood risks, including the evolving hazard characteristics, changing vulnerability and convoluted flood damages will be established. This will provide a strong scientific basis for managing flood risk in an uncertain climate future for various stakeholders.

城市暴雨洪涝灾害是当前政府与学术界高度关注的热点问题。在多年开展城市自然灾害风险研究方向国家自然科学基金项目的基础上，本项目借鉴国内外气候变化与城市暴雨洪涝灾害风险研究最新成果，选取受暴雨洪涝灾害影响严重的上海市中心城区为案例研究区，采用统计降尺度模型（SDSM）方法，率定实证研究区模型参数，构建城市气候变化降尺度模型，将IPCC全球气候模式的低分辨率降水预测结果,转化为适应于城市尺度的高分辨率预测结果；通过降雨-径流模型，分析降水变化与城市地表径流响应关系；并应用高分辨率洪涝数值模式，模拟未来不同情景的城市暴雨洪涝动态过程及淹没特征；在此基础上，进行城市典型承灾体暴露性与脆弱性分析，构建气候变化背景下城市暴雨洪涝灾害风险评估范式及模型，以丰富、充实和发展城市灾害风险评估理论方法体系，支持和优化我国城市应对气候变化背景下的灾害风险管理决策，提高我国城市的综合防灾减灾能力。

随着全球气候变化，城市暴雨洪涝灾害已成为当今国际社会与科学界面临的重大问题之一。本项研究以将气候模式的研究成果应用于未来城市暴雨洪涝灾害的预测和分析，属于灾害研究领域重要科学前沿。但基于气候变化降尺度分析开展的城市暴雨洪涝灾害风险评估还较少，尚未形成适合我国国情的气候变化背景下城市暴雨洪涝灾害风险评估的理论方法框架，代表性实证和应用案例较少，本项研究丰富和充实了我国研究的案例和方法。在项目的执行期内，项目组广泛吸纳国内外气候变化背景下的城市暴雨洪涝灾害风险研究成果，开展了多层次多角度的学术交流，进行了大量的野外实地调查和资料收集，采用最新研究方法Floodmap洪水数值模拟，系统分析研究区暴雨洪涝灾害的气候变化响应机制，通过构建的SDSM上海降尺度模型预测，开展了不同情景下暴雨洪涝灾害的危险性模拟和风险评估。研究结果主要有：（1）构建了上海市极端降水的气候变化响应与风险评估模式；（2）基于Floodmap了开展上海暴雨洪涝灾害高精度数值模拟；（3）基于多情景模拟了黄浦江流域极端风暴洪水危险性和动态风险演化趋势。（4）基于情景的我国极端降水的时空特征和风险分析。（5）开展多情景多尺度的洪涝实证模拟研究。