Alleviating the flood risk of critical water supply sites: asset and system resilience

Flooding can have severe impacts on the water supply services and adaptation responses for the provision of high-quality water supplies are necessary to cope with the risks exacerbated by climate change. This paper explores the planning process for adaptation strategies, emphasizing current research and modelling constraints and comparing resilience strategies. The flood hazard, vulnerability and impact were assessed based on information provided by the Environment Agency, local knowledge and network modelling of outages. Improvements in flood estimation were suggested to extend the range of scenarios analysed and the geographic cover and scope of models, whilst reducing and quantifying associated uncertainty. For evaluating consequences of widespread flooding, information on joint flood probabilities would be relevant, particularly where sites are interconnected. Considering the uncertainties in the approach, two strategies were explored to manage the flood risk, i.e. enhanced asset and system resilience. Low-regret options designed to protect a site from flooding were chosen and, where the population at risk is high, those were complemented with long term strategies for increased robustness of supply network to a multiplicity of risks.