Grays Harbor Estuary, Washington. Report 6. 45-ft MSL (40-ft MLLW) Navigation Channel Improvement Studies; Hydraulic Model Investigation.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MISS
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The existing, comprehensive fixed-bed model of the Grays Harbor estuary was used to determine the effects of enlarging deepening and widening the existing 35-ft-deep channel to a depth of 45 ft msl. One 45-ft improvement plan consisting of 23 groins and a relocated turningsettling basin was also investigated. Model tests were conducted on the above plans to determine effects on tidal heights, current velocities and patterns, salinity intrusion, dye dispersion, and channel shoaling. The scope of data collected while testing the improvement plan was not as extensive as for the enlarged channel itself however, the data obtained were considered sufficient to define the effects resulting from the plan. Compared with the 45-ft msl channel without improvements, the 45-ft msl channel improvement plan 1 had very little effect on current velocities or patterns. Tidal heights in the vicinity of the groin field were increased by about 0.3 ft. Downstream from Bowerman Airport, depth-averaged salinities were increased by about 1 ppt, while they were reduced by about the same amount upstream from the airport. The upstream extent of saltwater intrusion will decrease slightly. The flushing rate of a dye released near Cosmopolis was improved, especially in the area of the improvement plan. Overall shoaling rates in the various channel reaches were changed only slightly less than 10 percent however, shoaling will increase significantly in several localized areas which are already subject to high rates of accumulation.
- Civil Engineering