An exact reanalysis technique for storm surge and tides in a geographic region of interest

• A technique is presented for simulating surge after a local change to a domain.
• Changes may correspond to infrastructure design alternatives and failure scenarios.
• The cost to perform a simulation afterward is made comparatively very small.
• Results thereby produced are exact: the technique is not based on approximations.
• Derivations and proofs are bolstered by large-scale numerical experiments.

Understanding the effects of storm surge in hurricane-prone regions is necessary for protecting public and lifeline services and improving resilience. While coastal ocean hydrodynamic models like ADCIRC may be used to assess the extent of inundation, the computational cost may be prohibitive since many local changes corresponding to design and failure scenarios would ideally be considered. We present an exact reanalysis technique and corresponding implementation that enable the assessment of local subdomain changes with less computational effort than would be required by a complete resimulation of the full domain. So long as the subdomain is large enough to fully contain the altered hydrodynamics, changes may be made and simulations performed within it without the need to calculate new boundary values. Accurate results are obtained even when subdomain boundary conditions are forced only intermittently, and convergence is demonstrated by progressively increasing the frequency at which they are applied. Descriptions of the overall methodology, performance results, and accuracy, as well as case studies, are presented.