A new framework for building global flood models for the present day and future climates

In recent years there have been many new global datasets and methodological advancements that could be utilised by hydraulic models to help better understand global flood risk both in the present day and in the future. A major challenge facing modellers is how to incorporate these new datasets to improve the understanding of flood risk in both well, and less well, developed countries using a consistent approach, particularly as the latter of these contain increasingly larger exposures to floods.

This new framework presents a computationally efficient yet flexible approach that seeks to utilise new global datasets and allows flood hazard maps to be calculated anywhere in the world, for any event severity (within a pre-defined range) and for any future climate scenario. The framework can be applied to all three of the major flood perils; fluvial, pluvial and coastal.

At the heart of the framework is an efficient post-processing methodology that incorporates outputs from leading climate models, flood defence datasets and a baseline set of simulations spanning a range of evert severities. Furthermore, the flexible approach allows users to modify assumptions of flood defences and incorporate new climate simulations as and when they become available to quickly re-calculate flood hazard.

We present here the full modelling chain, from input data through to flood hazard outputs covering all aspects of modelling, from determining model boundary conditions and estimating channel bathymetry, to post-processing the presence of flood defences and interpolation to future climate scenarios. We show that such an approach is able to replicate explicitly modelling the scenarios required at a fraction of the computation cost and demonstrate how this is crucial to anyone wanting to understand how exposure to floods may change into the future.