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Shoreline Behaviour

The Columbia River littoral cell shoreline prograded for centuries before human intervention altered the processes that influence change along the coast.  Prior to human intervention, the littoral cell coast featured slow, steady progradation.  However, following the installation of dams on the Columbia River and jetties at the Grays Harbor and Columbia River estuaries, shoreline change occurred much more rapidly.  Coastal change over the past century has been quite dramatic, developing new landforms as sediment accumulated (e.g., Ocean Shores, Fort Canby) while at the same time eliminating public infrastructure and private property in rapidly eroding areas (e.g., North Cove).

To develop a detailed understanding of how the shoreline has changed in the littoral cell required the recovery of historical data from a variety of sources.  The primary tool used to link the variety of data sets is geographic information system (GIS) software.  Using GIS, it is possible to generate historic shoreline data in a common coordinate system, available for quantitative analysis.  The Southwest Washington Coastal Erosion Study is currently generating digital shorelines from a variety of sources, including  National Ocean Service Topographic Sheets (NOS T-sheets), aerial photography, and field surveys.  This data provides a foundation for documenting and understanding shoreline changes which have occurred over the past 130 years.  The knowledge gained through this investigation is one component of predictive models that are being used to forecast future coastal conditions.

Currently, historical shoreline positions of the littoral cell have been generated using NOS T-sheets from 1870s, 1920s, and 1950s.  Aerial photography has been used to generate at least one shoreline per decade since the 1940s.  In addition to the regional shoreline data sets described above, local shoreline coverages have been generated in actively eroding areas and at the request of the Washington State Parks & Recreation Commission (e.g., Ocean Shores, Damon Point, Fort Canby).  Check the Study data page to review a complete inventory of shoreline data sets.  A description of the technique used to convert paper maps to digital files can be viewed in the National Ocean Service Topographic Sheets section of this website, and deriving digital shorelines from aerial photography can be found here.

Select a sub-cell from the list below to view regional shoreline change patterns between 1870 and 1999.

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Ecology - SEA Program | USGS - Coastal & Marine Geology

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Maintained by CMAP, Washington Department of Ecology
Address questions and comments to George Kaminsky
Modified 22 Mar 2012