The Earth’s climate is changing. Global temperatures are increasing and in the future increased mean sea levels will become apparent. Mean sea level has the potential to increase by up to 1.8 m relative to present-day levels by 2100. Increased storminess, significant wave height and tidal range are also possible. The combination of these potential changes means that coastal communities and associated critical infrastructure will be under more pressure from extreme events in the future. Critical infrastructure provides essential services to keep modern society going, examples being railways and other transport links, communication lines and finally, electricity generation, transmission and distribution. While there are many risks to critical infrastructure, such as increased temperatures, droughts etc. The largest impact is from coastal flooding, both at the present day and using projections of future mean sea level. Critical infrastructure and communities on the coast and in floodplains are protected by defences, these are designed to be resilient to a defined standard. Increased mean sea levels will give the apparent effect of extreme events occurring more often, thus reducing the resilience capacity of infrastructure. Resilience can be defined as the capacity to recover quickly from difficulties. For this work, the difficulties are considered to be coastal flooding that occurs during an extreme event. Coastal communities could be subjected to larger inundation extents and damage cost from extreme events in the future due to a changing climate. This work has investigated the impact of different flood sources occurring together to see what effect this has on inundation and resilience including the cost of clean-up and repair. It has also assessed the joint probability of extreme water levels and significant wave height combinations to see if there is any variation in inundation resulting from extreme events with the same probability of occurrence. Finally, the resilience that a saltmarsh infers on the coast has been investigated and if this changes as the marsh erodes.
The questions covered by this research are:
1. What is the effect of combining different coastal flood sources while also being under a plausible future climate scenario on a coastal community?
3. Can we quantify the uncertainty surrounding the flood risk that could result from a given probability of an extreme event?
4. How much resilience does a saltmarsh contribute to a coastline and how does it diminish as the marsh erodes? What are the key factors in controlling the resilience of the marsh?