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A sample beach profile from a site in the Grayland Plains sub-cell, profile PC068  is shown below.  The beach profile begins landward of the primary dune, extends west over the dune crest and continues seaward to approximately Mean Lower Low Water (MLLW).

The seaward extent of the profiles varies because profiles collected during periods of high wave conditions (fall and winter profiles) limit the depth to which data can be safely obtained.  As illustrated in the figure, the summer 1997 survey (red line) has a relatively mild slope.  The winter 1998 survey (yellow line) reveals a significant volume of sediment loss and a steepening of the profile to a more concave shape.  By summer 1998 (green line) the profile experienced almost complete recovery. 

The summer 1998 profile includes two sandbars, with crests located 225 m and 350 m from the profile origin, and their associated troughs located 200 m and 325 m from the origin. These bars are typically located between MLLW and MHHW during the summer and are termed swash bars to distinguish them from the larger-scale sandbars located in deeper water. A berm, another feature associated with a summer beach profile, is located at a cross-shore position of approximately -180 m.  As the seasonal cycle continues, winter storms remove the berm and swash bars from the upper beach face, depositing the sediment in offshore sandbars.  Click on the graphic for an enlarged view.

This figure illustrates the contour change at profile profile PC068.  The contour change plot reveals the seasonal variability and a longer-term trend of the beach profile.  This example shows erosion in the winter and partial beach recovery in each of the two summer seasons.  By winter 2000, approximately 45- to 50-m (147- to 165-ft) of net erosion had occurred relative to the summer 1997 baseline at this location.

Both the 2.0-m and 3.0-m contours are included because analyses have demonstrated that the shoreline position (average high water line, AHWL), as derived from topographic maps and aerial photographs, is typically between these two elevation contours. Click on the graphic for an enlarged view.