North Jetty Performance and Entrance Navigation Channel Maintenance, Grays Harbor, Washington. Volume 2. Appendices
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICSLAB
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This report documents a study performed for the U.S. Army Engineer District, Seattle, to identify and evaluate feasible methods for reducing annual maintenance dredging in the outer Federal navigation channel at Grays Harbor, WA, by modification of the north jetty. Main interest was in potential reduction of southward sand bypassing the north jetty and preservation of the jetty should the neighboring beach erode. Considerable information and predictive capability were generated concerning the behavior of the Federal navigation channel and adjacent coastal and inlet shorelines. The study was conducted as a coordinated multi-disciplinary approach involving field measurement, physical modeling of the hydrodynamics and potential sediment pathways, geomorphic analysis and sediment budget formulation, and numerical modeling of waves, circulation and sediment transport, including modeling of shoreline change and bypassing. Numerous alternatives were considered and subjected to a screening process to identify feasible engineering and physically constructible alternatives within broad criteria. Six alternatives passed the screening and were evaluated. The alternatives concerned an innovative submerged spur that would be placed parallel to the shoreline along the north jetty, partial and full rehabilitation of the north jetty, and a combination of these alternatives with structures of different lengths. The sediment-control alternatives were evaluated relative to the existing condition. The study revealed many wide-area processes controlling sedimentation in and around Grays Harbor. The scale of change in southward-directed bypassing of sediment expected to occur after construction of any of the evaluated alternatives was found to be small compared to the scale of transport at the Grays Harbor entrance from sources originating outside the entrance or by being reworked and redistributed within the entrance.
- Physical and Dynamic Oceanography
- Civil Engineering
- Fluid Mechanics