© Paul Simkins / Arup

Cities and sea level rise: toolkit for flood hazard assessment and adaptation

In a world with a continuously increasing urban population, much of it concentrated in coastal cities, the predicted rise in sea levels resulting from climate change pose an additional – and in places dramatic — threat to the sustainability and the survival of affected cities. The global nature of the threat and the uncertainty of sea level rise, emphasised by the latest Intergovernmental Panel on Climate Change (IPCC) assessment report, demands an integrated approach not just to the protection of properties and businesses but also to urban infrastructure and services.

Arup’s experts in the areas of water, planning, geospatial modelling, safety critical engineering, and international development have been developing processes and tools that share a common agenda: resilience to future shocks and challenges, sea level rise being one of the most crucial ones. The outcome is a toolkit comprising a number of tools from different teams and disciplines.

The objective of this project was to create a comprehensive, accessible and delivery-focussed methodology that can be applied by any Arup team, independently of their geographical location. Additionally, to complement the wealth of knowledge already present in the firm, the research team included collaborations with the University of Leeds, Birkbeck College (University of London) and Old Dominion University in Norfolk, Virginia. It enabled knowledge transfer, experience sharing and verification of our working methods. Our knowledge has been enriched with insurance industry and policy aspects with regards to flood risk and climate change adaptation.

Sea level rise is a major factor in current and future city planning and prosperity. Recent research presents much higher foreseeable values of sea level rise than accounted for in published guidance to date.

Cities should consider a holistic dynamic adaptive approach that:
- protects against immediate hazards and damage
- develops foresight for what might happen
- revisits previous assumptions and projections frequently, and adjusts as needed.

Cities should build options to adapt to unforeseen changes and to retreat into the design of the urban coast. Adaptation to sea level rise, particularly flood risk, will require the cooperation of actors across the public and private sectors – it is rare that one body in a city can deliver this alone.

The 'right' intervention will be different in different cities, and a process of prioritisation should consider a range of criteria (social, economic and environmental factors) and allow a range of stakeholders to input.

We developed a guide identifying best practice and key issues, which can be used by Arup staff globally.  It presents a methodology to assess coastal flood risk, potential damages and analyse a range of intervention measures. The guide contains data sources for estimating sea level rise and its uncertainty, and the costs and benefits of a range of approaches, whether these are protection, adaptation or retreat. It is applicable regardless of the level of detail and data quantity available, as it presents the principles of the approach, with advice on decision-making depending on the data availability.

We strengthened links with academic partners and presented at the American Geophysical Union in 2015 and the UK Environment Agency flood risk conference in 2016. Three papers stemming directly from this project were accepted for the 3rd European Flood Risk Management conference in Lyon in 2016.

 

We have developed a common methodology towards estimation of sea level rise and a coherent approach to the assessment of risk/vulnerability and adaptation/mitigation interventions. Together these can enable Arup’s staff to effectively and efficiently address any requests concerning cities’ resilience against sea level rise, independently of geographical location. The research gives us the ability to tap into data collected by key cities around the world faced with sea level rise to benchmark our tools and methods. This research supports development of our knowledge and skills, demonstrating our commitment to technical advancement and continuous improvement in order to provide our clients with the best possible advice.