Strategies for coastal management of estuarine beaches by municipalities: a case study of Cliffwood Beach, NJ

Damaging coastal storms and sea level rise have placed many homes and recreational areas on estuarine shores at risk. The developed shore of Raritan Bay, NJ is particularly vulnerable. The US Army Corps of Engineers implemented coastal risk- management projects throughout many communities on Raritan Bay, but there are many segments of shoreline that are not included in these plans. Local differences in shoreline orientation and sediment supply caused by headlands and human structures have resulted in variations in beach processes and landscape changes overs small spatial scales. Municipalities have some freedom in managing beaches and dunes at these spatial scales using earth-moving equipment, sand fences, and vegetation, but scientific expertise is often missing at the local level. This study seeks to address ways coastal erosion and vulnerability of infrastructure can be addressed in an efficient and cost-constrained way using Cliffwood Beach, in Aberdeen Township, as a study site. Topographic data and sediment grain size characteristics were collected along six cross-shore lines. Erosion at this site reaches rates of up to 7.9 m3/m/year. Municipal management actions evaluated include soft solutions (beach nourishment, dune building and sand backpassing) and hard solutions (construction of wood bulkheads and geotubes). Soft solutions are favored to retain recreational and environmental values. Beach and dune volume calculations indicate that an initial nourishment project would require 17,500 m3 of fill material to reestablish the beach width and dune volume at the critically eroding area. Thereafter, 1,000 m3 of sand could be backpassed each year from accretionary portions of the beach downdrift to the eroding area to keep pace with erosion and make the protection project sustainable.M.S.Includes bibliographical reference