Centennial barrier-inlet evolution and coastal management: Lessons from undeveloped and developed phases at Barnegat Inlet, New Jersey

Barrier islands are long, thin, and dynamic landforms that provide unique ecological habitats, recreational areas and protection from storm damage . Major investments have been made to stabilize New Jersey’s highly developed barrier islands which host tourism infrastructure and private housing that provide central economic value. Maintaining this level of investment may not be sustainable due to the effects of climate change, sea-level rise and coastal communities’ potential lack of ability or willingness to cover the costs. To inform decisions related to a potential shift in coastal engineering investment, an understanding of past, more dynamic barrier island behavior is required. We couple historical map analysis and a process-based numerical model to determine the natural and anthropogenic effects that controlled Long Beach Island (LBI), a barrier island in southeastern New Jersey, alongshore evolution from 1839-1940 prior to major coastal engineering projects. Alongshore map analysis of this region indicates that LBI shifted from rotational nature to an overall retreat around the 1870s. We combine these results with a morphodynamic model that accounts for natural and anthropogenic effects to quantify barrier-inlet system evolution over centennial timescales.Our model uses an idealized barrier-inlet-barrier geometry including four reservoirs that represent updrift and downdrift barriers, tidal deltas and various sediment fluxes that connect these reservoirs. Results suggest the construction of small-scale jetties at LBI’s northern tip altered both local and system-wide sediment transport; that is, even limited coastal engineering can have major effects on the regional coastline response over decadal and centennial timescales.