Multi-Scale Topographic Anisotropy Patterns with Post-storm Barrier Island Recovery

The ability of beaches and dunes to recover following an extreme storm is a primary control of barrier island response to sea-level rise and changes in the frequency and/or magnitude of storm surges. Whereas erosion of the beach and dune occurs over hours and days, it can be years to decades before the beach and dune are able to recover to their pre-storm state. Recent evidence suggests that post-storm barrier island recovery can take up to 10 years following a storm that causes extensive washover, but those studies was dependent on a relatively simple analysis focused strictly on dune height and volume. Post-storm recovery of a barrier island involves subtle and multi-scale changes that have not previously been quantified and require a new morphometric approach. This study describes the use of scale-dependent distribution patterns of topographic anisotropy to characterize post-storm recovery of a barrier island and changes in the primary processes regimes. Recovery of Santa Rosa Island in Northwest Florida following Hurricane Ivan in 2004 is assessed using scale-dependent topographic relief and symmetry from LiDAR-derived DEMs. Scale-dependent changes in anisotropy through the recovery of the barrier island is used to separate dissipative small-scale recovery processes from large-scale features associated with the framework geology of the island that tend to persist and control island transgression.