Sustainable Solutions for Managing Compound Flood Risks under Future Uncertainties: The Case of Shanghai City and the Yangtze River Delta Region

Climate change presents a significant planning challenge for the Yangtze River Delta (YRD) Region, where urban build-up has given rise to what may be the largest concentration of adjacent metropolitan areas in the world. The YRD metropolitan region is centred at Shanghai, a mega city sitting on the south edge of the mouth of Yangtze River. YRD in general and Shanghai in particular face compound extreme flooding events caused by sea level rise, extreme rainstorms, astronomical high tides, storm surge, and upstream floods. To effectively mitigate the potential devastating consequences of such compound events in YRD will not only save human lives in the region but also contribute to sustainable development and social stability in China. This project will develop resilient adaptation measures to address future increasing flood risk under climate change and rapid socioeconomic development in YRD and Shanghai. We will quantify the compound flooding risks in the future based on the latest developments in climate and hydrodynamic modelling, and assess both direct (physical damage of buildings, assets and infrastructures, etc.) and indirect losses (economic losses along the input-output chain of the economy) caused by such compound events. We will then evaluate proposed mitigation and adaptation alternatives with a focus on Shanghai and visualize the sustainable solutions over the period of 2017-2100 based on the enhanced Robust Decision Making (RDM) method.

In this proposed project, the UK team will lead two working packages (WPs) and contribute to other packages. The UK team will lead WP-1 on climate change scenarios because the Met Office is currently routinely running a numerical weather prediction (NWP) forecast model with 1.5-km horizontal resolution over the UK (the UKV model). Based on this advantage, the UK team will work with Chinese partners to develop climate change scenario based on a regional climate model so as to create very high resolution rainfall data in the YRD region. In addition, the UK team will also contribute to the estimation of the joint distribution of co-occurring extreme weather/climate events (WP2). The UK team will lead WP-4 on Indirect Impact Assessment because Prof Laixiang SUN and his collaborators have advanced a mixed input-output model with supply constraint to effectively estimate the indirect impact of extreme events on socioeconomic sectors. The UK team will also make significant contributions to WP-6 on Evaluation of Potential Solutions because the team has made the most important contribution to the design on combining the robust decision making (RDM) scheme and the dynamic adaptive policy pathways (DAPP) for this project.

Both the overall missions of this proposed project and the contribution of the UK team to the project fit well with the EPSRC's theme on Living With Environmental Change. Our project has a well-specified emphasis on both the resource challenge and the infrastructure challenge under climate change, and shows a clear recognition of the important role that engineering and physical sciences can play in dealing with such challenges in the areas of Flood risk management, Water engineering, Coastal and waterway engineering, and Sustainable land management. In terms of modelling, we develop an integrated modelling framework to take into account the entire cascade of factors from the effect of climate change on storms and sea levels, to the physical and economic damages resulting from extreme events, allowing the robust determination of annual probability of damage states and a synthesized trade-off analysis of flood control pathways. This integrated, probabilistic analysis tool promotes the mission of EPSRC in modelling complexity using advanced mathematics and ICT.

The results of this project will be utilized by decisions makers in Shanghai to help decide exactly what scenario of flood defences to build. Economic damage analysis will allow them to probabilistically determine monetary damage values, and compare these with design, construction, implementation, and maintenance costs, allowing them practical knowledge of the costs and benefits of each project alternative. The flood maps generated will also allow the municipality to plan for first-response (fire, police) facilities in areas subject to higher probabilities of flooding and higher potential casualty counts. By projecting climate change 50-100 years into the future, it is expected that the results of this research will be useful to the municipality for at least this length of time. Furthermore, this research will detail how the flood protection measures proposed will protect Shanghai's areas of historical and cultural significance, such as the Bund.