New Storm Surge Catastrophe Model for Great Britain and Beyond

Country-wide catastrophe modeling of flood perils, including storm surge/coastal flood, presents a challenge of scale. On one end of the scale, the peril must be modeled over the entire region that could be impacted, and a sufficiently large catalog of stochastic storm events must be simulated to cover the risk. On the other end of the scale, location-level resolution is required to accurately simulate whether or not a particular property will flood during a given storm event (and how severely). Numerical hydrodynamic modeling presents an opportunity to overcome this challenge, but the modeling system must be stable and computationally efficient without compromising location-level accuracy.

The Delft3D Flexible Mesh Suite (Delft3D FM) is an open-source hydrodynamic modeling system created by Deltares to simulate storm surge and other coastal hydrodynamic processes. A key advantage of Delft3D FM is the robust, efficient, and stable mesh generation capability of the software. Combining this mesh generation technology with in-house expertise and detailed data for model initialization and wind/pressure forcing, the team at AIR Worldwide has created a Delft3D FM-based storm surge catastrophe model for part of Great Britain (England and Wales). This Great Britain coastal flood model captures storm surge risk from extratropical cyclones. Simulated historical surge events such as Storm Xaver (2013) and the North Sea Flood of 1953 will be shown, as well as modeled surge return periods. Finally, it should be noted that similar technology can be used for simulating tropical cyclone-induced storm surge risk in areas impacted by tropical cyclones.