The Urban Impacts Toolbox: An initial assessment of climate change flood adaptation options for Westport
This paper presents a simplified or rapid process for evaluating adaptation responses to projected climate change impacts as part of community planning, using flooding scenarios in Westport as a case study. The paper draws upon many of the tools found in "Impacts of Climate Change on Urban Infrastructure and the Built Environment Toolbox", and builds on the results presented in the second paper of this special issue. A key finding from the flood adaptation options case study for Westport was a demonstration of the process of an initial options assessment. This was in the context of constraints on resources and information, which is likely to be starting point for many climate change adaptation processes. For Westport, a preferred adaptation option was developed from a list of four options by varying the climate change parameters and running sensitivity tests. This was achieved using a rapid benefitcost ratio approach with the proviso that the results provide a strategic direction on where more detailed planning and investigation would be beneficial. The Westport case study showed that more stopbanks is the best option for flood protection for further study. In some circumstances, raising houses above the flood level is also an option deserving further investigation. In this context a long term plan to renew/rebuild structures at higher foundation levels could progressively reduce flood risks. On the other hand, options requiring extensive earthworks to widen the river and provide extra overflow capacity were shown to be poor options, even under a range of inputs conditions, and could be removed from further consideration.