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Title: Numerical simulation of the Coos Bay-South Slough complex
Authors: United States. Army. Corps of Engineers. Portland District
Butler, H. Lee
Keywords: Coos Bay
Navigation channels
Numerical simulation
Numerical model
South Slough, Oregon
Tidal inlets
Mathematical models
Tidal models
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; H-78-22.
Description: Technical Report
Abstract: Coos Bay Inlet, located on the south central coast of Oregon, provides tidal flow to two estuary systems: Coos River to the north and South Slough to the south. The upper reaches of South Slough constitute a National Marine Sanctuary, administered by the National Oceanographic and Atmospheric Administration. Charleston Harbor is located at the entrance into South Slough and is affected by continual shoaling problems within the harbor entrance channel. A two-dimensional numerical tidal model (WIFM) was used to investigate the tidal hydrodynamics of the inlet complex. Due to the nature of the complex geometry of the Coos Bay area, it was necessary to develop a capability of computing the tidal regime on a variable grid system. The primary objective of this study was to apply WIFM to the Coos Bay-South Slough complex to predict quantitatively the hydrodynamics (exclusive of sediment transport and wave action) of the tidal flow in the system and hence draw a comparison between existing conditions and alternate improvement plan conditions. In general, the improvement plans provide for: (A.) Construction of specified navigation channels. (B.) Alternate breakwater extensions west of the entrance channel. (C.) Alternate detached groins east of the entrance channel. Five alternate plans (plan 1 and plans A-D) were tested, and the results show that the introduction of any of the improvement plans as proposed would not produce any detrimental impact to tidal circulation in South Slough. The greatest effect on the hydrodynamics of the total system would occur with the installation of plan 1. Results for plans A-D indicate that the combination of a Charleston breakwater extension and one or more groins on the east side of Charleston Channel would best meet the District's needs in that they permit more control over the alignment of the Charleston Channel. Time histories of tide elevations and velocities are presented for selected stations throughout the Coos Bay-South Slough complex. Sample circulation patterns for four instances in the tidal cycle are presented for the verification conditions and for each plan. Total discharge through several key ranges in the system is graphed as a function of time. A wave refraction analysis, using a linear wave refraction model, was performed to determine wave energy levels penetrating the entrance to Coos Bay Inlet. Results are tabulated for six initial deepwater directions and six periods. An attempt was made to compute wave orthogonals extending into Coos Bay Inlet. Only those shallow-water waves whose azimuth is aligned with the entrance channel would propagate within the inlet system. Results obtained by the linear wave refraction code are very limited for sites such as Coos Bay due to the complex channel formation extending outward from the inlet jetties and shoal areas adjacent to the main channel as it progresses eastward toward Barview. NOTE: This file is large. Allow your browser several minutes to download the file.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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