Department of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, China.
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
Water Res. 2019 Dec 1;166:115067. doi: 10.1016/j.watres.2019.115067. Epub 2019 Sep 7.
Coastal mega-cities will face increasing flood risk under the current protection standard because of future climate change. Previous studies seldom evaluate the comparative effectiveness of alternative options in reducing flood risk under the uncertainty of future extreme rainfall. Long-term planning to manage flood risk is further challenged by uncertainty in socioeconomic factors and contested stakeholder priorities. In this study, we conducted a knowledge co-creation process together with infrastructure experts, policy makers, and other stakeholders to develop an integrated framework for flexible testing of multiple flood-risk mitigation strategies under the condition of deep uncertainties. We implemented this framework to the reoccurrence scenarios in the 2050s of a record-breaking extreme rainfall event in central Shanghai. Three uncertain factors, including precipitation, urban rain island effect and the decrease of urban drainage capacity caused by land subsidence and sea level rise, are selected to build future extreme inundation scenarios in the case study. The risk-reduction performance and cost-effectiveness of all possible solutions are examined across different scenarios. The results show that drainage capacity decrease caused by sea-level rise and land subsidence will contribute the most to the rise of future inundation risk in central Shanghai. The combination of increased green area, improved drainage system, and the deep tunnel with a runoff absorbing capacity of 30% comes out to be the most favorable and robust solution which can reduce the future inundation risk by 85% (±8%). This research indicates that to conduct a successful synthesized trade-off analysis of alternative flood control solutions under future deep uncertainty is bound to be a knowledge co-creation process of scientists, decision makers, field experts, and other stakeholders.
由于未来气候变化的影响，沿海特大城市按照现行保护标准将面临越来越大的洪灾风险。先前的研究很少评估在未来极端降雨不确定性下，替代方案减少洪灾风险的相对有效性。由于社会经济因素的不确定性和利益相关者之间存在争议的优先事项，长期的洪灾风险管理规划也面临着挑战。在这项研究中，我们与基础设施专家、政策制定者和其他利益相关者一起进行了知识共创过程，以开发一个灵活测试多种洪灾缓解策略的综合框架，以应对深度不确定性的情况。我们将该框架应用于上海市中心一次破纪录的极端降雨事件在 2050 年代重现的情景中。选择了三个不确定因素，包括降水、城市雨岛效应以及由于地面沉降和海平面上升导致的城市排水能力下降，以构建案例研究中的未来极端洪水情景。在不同的情景下，检验了所有可能解决方案的降低风险的性能和成本效益。结果表明，海平面上升和地面沉降导致的排水能力下降将对上海市中心未来洪水风险的上升贡献最大。增加绿地、改善排水系统以及具有 30%径流量吸收能力的深层隧道的组合是最有利和最稳健的解决方案，可以将未来的洪水风险降低 85%（±8%）。这项研究表明，在未来深度不确定性下，对替代防洪解决方案进行成功的综合权衡分析，必然是科学家、决策者、现场专家和其他利益相关者的知识共创过程。
