Long Beach, Rockport, Massachusetts Sediment Transport Study

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As a result of natural and man-induced evolution of the Long Beach shoreline in Rockport, the beach system fronting much of the shoreline has eroded significantly over the past 100+ years, primarily due to a deficit of littoral sediments.  In general, this rate of landward shoreline migration has decreased over time, as the seawall constructed in the 1930s prevented landward migration of the shoreline, but the elevation of the beach continued to lower as the overall beach profile migrated landward.  For the past several years, the Town of Rockport has become concerned with the condition of the aging seawall infrastructure, as well as the longevity of the barrier beach system.  In addition, the low-lying nature of the landform has created other concerns related the stability of the sewer line servicing the leased properties along the beach system.   

Following an in-depth evaluation of beach management history and a quantitative assessment of coastal processes, beach management scenarios were tested to assess their viability toward long-term sustainability of the beach system and the adjacent infrastructure. 

This study included analyses of historical data sets that span the time between 1851 and then present.  This included analyses of shoreline change and cross-shore profile change.  The cross-shore profile analysis utilized a 1931 survey of the beach which included the complete upland area of the barrier spit down to an elevation near mid-tide.

Coastal processes that act to shape the evolution of Long Beach over time were further investigated with the development of a shoreline change model of the entire Long Beach littoral cell.  The model code was developed by Applied Coastal to simulate long term shoreline change and beach fill performance.  The model of average annual conditions at Long Beach provided insight into the nature of the long-term erosion issues experienced at the beach.  Net longshore sediment transport is essentially zero, as is typical for pocket beaches in equilibrium with their environment.  Volume loss from the beach profile is due to cross-shore movement of sand.  Beach nourishment was demonstrated to be a viable option for shoreline restoration.