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Beach Morphology Monitoring Program
Nearshore Bathymetry - Oysterville
To resolve medium-scale morphologic change, a 2 to 3 km-long section of coast within each sub-cell was surveyed in both 1998 and 1999 with 200-m profile spacing. The figure below illustrates a portion of the nearshore planform in 1998 along the Long Beach sub-cell (km 68 – 71). This stretch of coastline has a long-term trend of accretion but has been relatively stable since the inception of the monitoring program in 1997. A distinctly linear outer sandbar in approximately 6.0 m water depth and a crescentic middle bar in 4.0 m of water are evident in the figure. Above the 1.0-m contour (NAVD 88) the morphology resumes patterned behaviour with large-scale rhythmic mega-cusps.
Subsequent nearshore profile data reveal a large redistribution of sediment in the cross-shore, the growth of a large outer bar and landward migration of the middle bar. Over the 2.5 km (both in the cross-shore and alongshore) gridded bathymetric surface there was no appreciable loss of sediment between 1998 and 1999 and no net shoreline change. In the cross-shore, beach profile change out to 11 m (MSL) was measured.
