Survey of shoreline structures, Popponesset Beach, MA

Abstract

The structures along a 12 km section of the shoreline of Cape Cod, Mass., were evaluated for condition and effectiveness at protecting the coast. Structures in the area include groins, jetties, revetments, and seawalls; each has been located, photographed and described. The region has been subject to erosion in recent years, including the loss of a 1 km section of barrier spit. The role of shoreline structures in controlling or enhancing the erosion was examined as part of a larger study of coastal processes in the area. The shoreline structures serve two primary functions: beach enhancement and protection of the bluffs from erosion. The structures• effects on bluffs and beaches in their immediate vicinity (approximately lOOm along the coastline to the north and south of the structure) are detailed in this report. Seawalls generally protect the cliffs into which they are built without enhancing erosion of surrounding bluffs, though the bluffs are protected at the expense of the beaches in the central area (Meadow Point). Large scale changes in beach configuration are not primarily caused by local, small-scale structures, but rather by a more regional paucity of sand input into the system. This scarcity is caused in part by large jetties controlling inlet flows to Waquoit Bay, which impedes free transport of sand into the area.