Balancing complexity and efficiency in coastal flood risk modelling

As climate change drives sea level rise and raises critical questions about the design and efficacy of flood defences, there is an increasing demand for high-resolution coastal flood data. As a commercial provider of flood risk data to the insurance and banking sector, we have users that emphasise accuracy. For instance, these users seek not only to determine if floodwaters might reach a property but also whether they will exceed the height of the doorstep. While advancements in flood modelling continue to meet these growing needs, a persistent challenge remains: how can we balance the need for high accuracy with the practical constraints of production costs and the need for timely data delivery?

Focussing on coastal flood mapping examples in the UK, our presentation will compare outputs from two ends of the modelling spectrum: complex full hydrodynamic modelling and a simplified projection approach. Simplified approaches often face criticism for their limitations, but we will argue that they can provide valuable – as well as timely and efficient – outputs, when applied appropriately and with a clear understanding of their constraints.

This work aims to explore the importance of balancing advanced and simplified techniques, offering insights into the factors that most significantly influence flood modelling outputs. For example, we examine whether the choice of input data (e.g., the terrain data, the extreme sea levels) has a greater impact on results than the modelling approach itself (hydrodynamic compared to projection modelling techniques). By highlighting the trade-offs and opportunities, we aim to contribute to a more nuanced understanding of how to optimise coastal flood risk data production to meet user needs.