Coastal Hazards: Multi-hazard controls on Flooding and Erosion (CHAMFER)

Coastal hazards pose a significant risk to people, property, and infrastructure worldwide and in the UK. For example, over 1.8 million homes are at risk of coastal flooding and erosion in England alone and coastal flooding is recognized as one of the top two environmental hazards in terms of impact in the 2020 National Risk Register. The occurrence, intensity and impacts of coastal flooding and erosion are projected to increase with climate change and will have major socio-economic consequences. Historically, coastal protection has relied on overwhelming use of hard engineered defence schemes, but adverse effects and high costs of these schemes have driven advocacy of coastal practices that are based on Working with Natural Processes (WWNP). However, future changes in regional sea level, storms, pluvial and fluvial inputs, coastal habitats, and their interrelations lead to significant epistemic uncertainties (due to limited knowledge) about controls on flooding and erosion and limit the implementation of WWNP schemes. Questions remain on how multiple terrestrial and marine drivers of extreme hydrodynamic conditions will combine to control coastal flooding and erosion in the future, on the vulnerability and efficacy of protective services afforded by coastal habitats, and on the performance of WWNP solutions on coasts that already have partial protection by traditional engineered coastal defences.

Event-scale coastal flooding and erosion mainly occur in response to synoptic scale meteorological events. These meteorological events can result in a series of individual hazard components to coastal environments, such as storm surges, extreme waves, extreme rainfall, and extreme river flows. However, these hazard components are not independent of each other, and coastal flooding and erosion commonly arise from the collective impact due to interrelated and/or successive hazard components. In other words, coastal flooding and erosion are controlled by multi-hazards.

The CHAMFER project will characterise how multi-hazards at the coast control coastal flooding and erosion and determine how these multi-hazards will respond to climate change and coastal management. We will deliver a new community modelling system coupled across terrestrial and marine sectors, numerical simulations of which will be used to support multi-hazard analyses under present and future scenarios. This will be combined with an assessment of the role of coastal habitats resulting in national maps for protective services and vulnerabilities of coastal habitats to climate-driven multi-hazards. We will provide tools to analyse the efficacy of future WWNP schemes. CHAMFER will rely on a multi-scale approach both spatially, by considering UK/GB scales and more local spatial scales, and temporally, by considering responses to meteorological events under long-term climate-related or management-related changes. CHAMFER includes significant elements of co-design with stakeholders and we will work with government departments, public sector organisations, and industry users to inform and support coastal protection and adaptation options.