RESTORATION OF NATURAL GEOMORPHIC PROCESSES TO CREATE BARRIER ISLAND HABITAT ON ASSATEAGUE ISLAND, MARYLAND

In 1998, multiple northeasters threatened to breach Assateague Island National Seashore, Maryland in an area that was experiencing rapid erosion due to sediment starvation by updrift jetties. To prevent breaching in the interim period before a long-term sediment bypassing project could commence, a constructed foredune was emplaced on the island. This foredune was designed using an engineering model to allow occasional overwash, and was placed at a setback distance equal to the expected interim shoreline erosion. Because the design assumptions did not match the actual meteorological and erosional conditions that followed, the foredune proved impenetrable to overwash and disrupted other morphological processes, resulting in undesirable habitat changes.

The National Park Service partnered with the U.S. Army Corps of Engineers to address these unintended consequences by restoring the natural geomorphologic processes that create and shape barrier island habitats. Analyzing datasets including island topography, overwash frequency, and meteorological conditions, and revising the assumptions and input data used in the engineering model, the team designed and built multiple pathways through the foredune.

These new pathways, which replicate the natural overwash topography found elsewhere on the island, functioned as hoped during recent storms, allowing creation of new overwash fans and build-up of the interior island elevation. Habitat response will be quantified over the coming year to evaluate the biological effects of restoring geomorphic processes, and will guide decisions on whether additional management action is necessary.