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Oregon Beach and Shoreline Mapping and Analysis Program: Pacific Northwest Estuaries and Shores  

 

Beach Processes in Oregon

 

Oregon's beaches are subject to a wide range of coastal processes that collectively can contribute to sustained periods of erosion, causing the toe of coastal dunes or high bluffs to retreat landward threatening peoples properties and important infrastructure located too close to the beach.  These erosion events are largely driven by the occurrence of major storms that produce large waves coupled with high ocean water levels, which enables the wave swash to reach to much higher elevations at the shore eroding the beaches, dunes and bluffs.  Periodically these erosion processes may be enhanced due to the occurrence of a major El Nio.   El Nios occur approximately every 2 to 7 years and can increase the risk of erosion of beaches due to both an increase in the mean wave heights observed along the Oregon coast, but also due to an increase in the mean elevation of the sea by some 50 -60 cm (1.5 - 2 ft).  In addition, El Nios also influence the predominant tracks of the storms as they cross the North Pacific ocean, so that ocean waves tend to arrive at the shore mainly from the southwesterly direction.  This last process can result in considerable erosion along the southern ends of Oregon's littoral cells and north of the mouths of bays and streams.  Thankfully, the erosion of Oregon's beaches during the winter is not entirely one way traffic (i.e. landward) since it is also balanced by periods of beach rebuilding during the summer and during periods characterized by lower average wave heights (e.g. during the period from 1988 to 1996).

 

Clatsop Spit, Feb 2006

Netarts Spit, Feb 2006

References:

Komar, P.D., 1997. The Pacific Northwest Coast: Living with the Shores of Oregon and Washington. Duke University Press, Durham and London, 195 p.