LONG-TERM BEACH RESPONSE TO SHORE STABILIZATION STRUCTURES ON THE OREGON COAST

Abstract

Increased development along the Oregon coast has led to heightened concern over beach erosion. As a result, more shore stabilization structures have been erected in recent years. A long-term field monitoring program, involving seven typical structures located on the central Oregon coast, was initiated in the spring of 1986 to quantify the effects of shore stabilization structures on the surrounding beach and adjacent properties. All structures are rip-rap revetments or seawalls. Volumetric changes of the subaerial beach at each site were examined at scales ranging from the entire beach surrounding the structure to the beach in the immediate vicinity of the structure. When the data coverage and site geometry permitted, a far field control section was utilized to compare the volumetric response of a portion of beach relatively uninfluenced by the presence of the structure with that of the beach on the two structure flanks. Measurements are presented for the seven structures over the observation period of ten years to document the long-term effects the structures are having on the fronting beach and adjacent unprotected properties. Ten years of monitoring has revealed that the structures at these seven sites are having no adverse impacts on the surrounding beach or adjacent properties. This can be attributed to the limited amount of wave attack that the structures have experienced. The structures are built high on the profile, and experience wave attack only during the most severe storms.