Informing adaptation pathway approaches for vulnerable coastal infrastructure

Hard-engineered defences protect critical coastal infrastructure that, without long-term adaptation planning, will face increased risk of flooding from sea-level rise (SLR). The adaptation pathway (AP) approach has been developed to improve long-term planning for climate change under future uncertainties, however, there remains a lack of asset level examples to inform coastal infrastructure decisions at a sector level. In this paper, a ‘performance-orientated’ AP approach is developed which provides a technique for generating future decision ‘pathways’ for coastal transport infrastructure using open-source data and standard guidance techniques. The application and method are novel because they combine a modified fragility curve approach with climate change projections of sea-level rise and also easily accessible satellite observational data (InSAR) related to local coastal ground movement. Applied to a local railway branch line it is demonstrated, that absent of any adaptation, approximately 83 % of the assets will fail the set standard of protection ( SoP ) by 2050 . It is also shown that combinations of adaptation options can delay defence protection ‘tipping points’ beyond the study period ( > 2150 ). Finally, the use of satellite observations in AP approaches can allow for more detailed and localised information regarding defence failure timings. The ‘performance-orientated’ AP approach can be an insightful tool for strategic planning and policy, and can be achieved without significant organisational capacity.