USGS Research Contributes to Assateague Island RestorationMitigating 70 Years of Coastal Erosion Due to Ocean City Inlet Jetties
Ocean City inlet, MD, is one of the most striking examples of the unintended consequences of engineered inlets causing increased erosion of adjacent barrier islands downdrift from the jettied inlet.
The Ocean City inlet opened during a 1933 hurricane, and soon after, the twin stone jetties were built by the U.S. Army Corps of Engineers (USACE) to maintain the inlet for navigation. However, the jetties also severely disrupted littoral-inlet processes, trapped sand on the north side of Fenwick Island (site of the Ocean City amusement park and parking lot), and severely starved Assateague Island National Seashore to the south of sand.
The result of almost 70 years of disrupted sand transport along the coast has been an offset in the two barrier islandsFenwick and Assateagueby approximately 1 km, along with accelerated erosion, reduction and alteration in beach-berm heights, and loss of critical beach and dune habitats. The effects attributable to the jetties have extended about 15 km southward from the inlet.
To mitigate the effects of Ocean City inlet, a bold plan of coastal restoration began in August 2002, with a price tag of $63 million. The restoration is a partnership between the National Park Service (NPS), the USACE, and the Minerals Management Service (MMS).
The plan to restore Assateague consists of an initial, short-term phase in which 1.8 million cubic yards of sand dredged from Great Gull Bank, a linear shoal on the shelf, will be added to Assateague Island beaches.
A longer-term phase will follow over the next 25 years, in which sand will be mechanically dredged and bypassed from the Ocean City inlet area and placed on Assateague Island beaches on spring and fall schedules, in a phased approach intended to replicate natural processes.
This plan of restoration could become a model for other coastal regions where engineering structures have disrupted littoral processes, causing increased erosion and land loss.
Science has been instrumental in understanding the connection between inlet processes and erosion of Assateague Island and in designing the restoration plans. The USGS' role, in cooperation with the Maryland Geological Survey and the NPS, has been to
in this issue:
Assateague Island Restoration