2007 GSA Denver Annual Meeting (28–31 October 2007)

Paper No. 5
Presentation Time: 8:00 AM-12:00 PM


BARBER, Don, Geology Department, Bryn Mawr College, 101 N Merion Ave, Park Sci Bldg, Bryn Mawr, PA 19010, dbarber@brynmawr.edu

The beaches of coastal New Jersey typify developed retrogradational shorelines in the US. Shoreline development begins with construction on residential properties. While buildings are initially sited well back from the shoreline, long-term shoreline retrogradation eventually threatens the most seaward properties. The shoreline is hardened with sandbags or rock revetments to protect threatened properties. The erosion threat often is perceived to be temporary. However, as shoreline retrogradation continues, more properties suffer from wave attack. As time goes on, seawalls and other hard-stabilization structures front long coastal reaches. These structures ultimately narrow and/or destroy the recreational beach through active (e.g., wave reflection and scour) and passive (e.g., placement loss) effects. The pervasive loss of dry beach, coupled with storm damage when walls are breached, leads inevitably to a downturn in coastal property values and revenues associated with beach tourism. At that point, only two beach-compatible options remain: 1) rehabilitate the beach in a more landward location via property abandonment and removal of hard stabilization structures; i.e., Organized Retreat; or 2) re-create the beach seaward of the existing structures through a massive program of Beach Nourishment. Both options are very costly. On coasts where relative sea level is rising and long-term shoreline retrogradation is occurring, both approaches yield only temporary solutions. On developed barriers adjacent to tidal inlets, channel migration adds another dimension to the land loss problem. Navigational needs may rule out updrift beach nourishment in favor of ever-increasing shoreline fortification.

The evolution of two New Jersey beaches (Monmouth Beach and Longport) illustrates the geomorphological and management patterns described above. Monmouth Beach, on the northern NJ coast, has undergone massive beach nourishment. Longport, adjacent to Great Egg Harbor Inlet in southern NJ, will probably continue to be structurally fortified, unless major, but not unprecedented, inlet channel realignment occurs. In addition to outlining the recent history of these two beaches, forecasts and recommendations are made concerning these and nearby beaches, as well as for similar beaches elsewhere.