SHORELINE RETREAT ALONG THE NORTH SHORE OF THE DELAWARE BAY, NEW JERSEY

A twenty km long segment of shoreline in the vicinity of Sea Breeze, New Jersey was selected to study shoreline retreat. A series of aerial photos from the 1930’s to 2007 were analyzed using GIS. The rate of shoreline retreat was estimated by placing a contour point of the 1930’s shoreline over the 2007 aerial photo. The distance between each contour point was 500 m. The change in distance was measured perpendicular to the modern shoreline.

In up to seventy seven years the shoreline in the study area was eroding with an average rate of 2.02 m/yr. The identified features with the highest rate of erosion along the Delaware Bay shoreline are the headlands with open unprotected marsh shorelines. The maximum rate of headland erosion is 4.77 m/yr. The small community of Sea Breeze, populated by ~100 people, was built behind a small barrier more than 100 years ago. In the early 20^th century, a twenty meter wide beach and boardwalk used to attract vacationers from Philadelphia. The shoreline was protected by engineering structures of different designs for the last several decades which probably slowed down the rate of shoreline retreat to 0.92 m/yr. The latest sea wall constructed in May of 2007 failed to protect the road and houses from transgression, causing the population to abandon their houses and evacuate the area by the end of 2009.

Rising sea level, increased frequency of flooding and storm erosion are the likely factors for the shoreline erosion. Geomorphologic analysis of coastal features, estimated rates of shoreline erosion, an understanding of the mechanisms causing environmental changes, and the factors that regulate the rate of these changes are very helpful in mitigating coastal hazards along the Delaware Bay shore.