Making decisions regarding long term investment in flood protection and adaptation typically results in the need to implement large interventions which are costly, require substantial amounts of time to be completed and have far reaching consequences into the future. Current engineering practice provides a range of possible methods for selecting these interventions based on engineering expertise and the use of latest optimisation and other technologies. However, solutions identified this way are typically precautionary with respect to under-protection and inflexible in that they cannot be easily adapted to any future changes. Whilst this was acceptable in the past when the rate of change of external drivers such as climate change or urbanisation was slow in comparison with the system lifetime, it is no longer appropriate and a different approach is needed. This is particularly the case for multi-functional flood defences as the variety of future changes in relevant conditions and requirements is likely to be much larger than for the more traditional mono-functional case. What complicates matters is that uncertainties in the long-term development of key drivers such as climate change, economic development, social acceptance of risk, and the like, often cannot adequately be quantified using probabilistic analysis.
To date, little has been done yet to develop a clear and systematic methodology for identifying and evaluating flexibility in design for the context of flood protection and adaptation. The focus and core objective of this research project is therefore to develop such a methodology, with particular reference to multifunctional flood defences.