Simulating barrier island response to sea-level rise with the barrier island and inlet environment (BRIE) model v1.0

Abstract. Barrier islands are low-lying coastal landforms vulnerable to inundation and erosion by sea-level rise. Despite their socio-economic and ecological importance, their morphodynamic response to sea-level rise or other hazards is poorly understood. To tackle this knowledge gap, we outline and describe the BarrieR Inlet Environment (BRIE) model that can simulate long-term barrier morphodynamics. In addition to existing overwash and shoreface formulations, BRIE accounts for alongshore sediment transport, inlet dynamics, and flood-tidal delta deposition along barrier islands. Inlets within BRIE can open, close, migrate, merge with other inlets, and build flood-tidal delta deposits. Long-term simulations reveal complex emergent behaviour of tidal inlets resulting from interactions with sea-level rise, and overwash. BRIE also includes a stratigraphic module, which demonstrates that barrier dynamics under constant sea-level rise rates can result in stratigraphic profiles composed of inlet fill, flood-tidal delta and overwash deposits. In general, the BRIE model represents a process-based exploratory view of barrier island morphodynamics that can be used to investigate long-term risks of flooding and erosion in barrier environments. For example, BRIE can simulate barrier island drowning in cases where the imposed sea-level rise rate is faster than the morphodynamic response of the barrier island.