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Title: Waves, hydrodynamics and sediment transport modeling at Grays Harbor, WA
Authors: Demirbilek, Zeki
Lin, Lihwa
Smith, S. Jarrell
Hayter, E. J.
Smith, Ernest R.
Gailani, Joseph Z.
Norwood, Gregory J.
Michalsen, David R.
Keywords: Channel realignment
Channel sedimentation
Dredged material disposal sites
Grays Harbor (Wash.)
Numerical modeling
Return period
Sediment transport
Publisher: Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (Engineer Research and Development Center (U.S.)) ; no.ERDC/CHL TR ; 10-13
Abstract: This numerical modeling study was performed for the purpose of addressing short-term and mid-term dredge material management issues for the Federal Navigation Project at Grays Harbor, Washington. Seattle District (NWS) is also currently evaluating Grays Harbor navigation channel realignment in the Point Chehalis/Entrance reach. Historic trends in survey data indicate this area is naturally scouring a new thalweg. The realigned channel would take advantage of this new thalweg developing just north of the present channel and relocating the channel is hypothesized to reduce annual dredging quantities. The impact of dredged material placement sites on channel maintenance is also examined. The three dredged disposal sites of interest considered in the present study are the Point Chehalis Disposal Site (PCDS), South Jetty Disposal Site (SJDS), and Half Moon Bay Beneficial Use Site (HMBBUS). Currently, the inner harbor sediments (silts/clays) are placed exclusively at the PCDS and SJDS, and the outer channel sediments (>95% marine sand) are placed at the three sites. The NWS is considering the realignment of the Point Chehalis/Entrance reach of GH navigation channel in an attempt to establish optimal locations for the PCDS and SJDS. The key issues of interest to the NWS investigated in this study were: a) changes in waves and hydrodynamics at GH navigation channel over time scales of 0.5 to 5 years, b) consequences of channel realignment on waves, hydrodynamics and sedimentation of GH navigation channel, c) sediment transport pathways in the lower GH and at three dredge material placement (DMP) sites, and d) channel infilling estimates from frequently occurring, low energy storms and less frequent, but more energetic storms. These issues were examined for two channel alternatives: “Existing” channel configuration at GH/HMB complex, and “Realigned” channel configuration. The Realigned channel was modeled with and without the Existing channel filled. Wave and hydrodynamic modeling results for the Existing and Realigned channels were used in the sediment modeling for the associated short- and long-term sediment transport at GH/HMB complex. Waves and hydrodynamics were modeled using CMS-Waven and ADCIRC models, which were validated with 1999 and 2003 field data sets collected by USACE at GH that included wave, water level and velocity measurements. The bathymetry data for these years were provided by the NWS. The tidal and wind forcings of model boundary conditions were developed using a 38-yr deepwater data set to investigate channel sedimentation and sediment transport patterns in the Grays Harbor’s outer channel region from the entrance to Point Chehalis. Sediment transport modeling was performed using GTRAN, MPFATE, LTFATE and SEDZLJ models. Detailed description of wave, hydrodynamic and sediment transport modeling are provided in this report.
Description: Technical Report
Gov't Doc #: ERDC/CHL TR-10-13
Rights: Approved for public release; distribution is unlimited
Appears in Collections:Technical Report
Technical Report

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