Can Barrier Islands Survive Sea-Level Rise? Quantifying the Relative Role of Tidal Inlets and Overwash Deposition

Barrier island response to sea-level rise depends on their ability to transgress and move sediment onto and behind the barrier, either through flood-tidal delta deposition or via overwash. Our understanding of these processes over decadal or longer timescales, however, is limited. Here we use a recently developed barrier island model (BRIE) to better understand the interplay between tidal dynamics, overwash fluxes, and sea-level rise on barrier coasts and barrier island stratigraphy. Model results suggest that in microtidal environments with large alongshore sediment transport fluxes, tidal inlets are ephemeral and migrate rapidly. These conditions lead to effective deposition of flood-tidal deltas and allow inlets to constitute most of the landward sediment flux. Whether barrier islands can survive sea-level rise depends on the combined landward sediment flux from overwash and flood-tidal delta deposition, likely making barrier islands with artificially stabilized inlets (via jetty construction or maintenance dredging) more vulnerable to sea-level rise.