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Title: Los Angeles and Long Beach Harbors Model Enhancement Program : three-dimensional numerical model testing of tidal circulation
Authors: Port of Long Beach.
Port of Los Angeles.
United States. Army. Corps of Engineers. Los Angeles District.
Coastal Engineering Research Center (U.S.)
Keywords: Harbors
Los Angeles Harbor
Long Beach Harbor
Numerical models
Three-dimensional models
Tidal circulation
Ocean circulation
Tidal currents
Mathematical models
Publisher: Coastal Engineering Research Center (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; CERC-90-16.
Description: Technical Report
Abstract: To meet future needs, the Ports of Los Angeles and Long Beach have undertaken a long-range cooperative planning effort known as the 2020 Plan. Under this master plan, a number of phased plans have been determined to accommodate future needs. These plans involve deepening of ship channels and harbors and creation of new landfills. The purpose of the study described in this report was to determine three-dimensional (3-D) hydrodynamics of tidal and wind-driven circulation for existing conditions as well as a plan condition selected by the ports. This goal was accomplished by applying a state-of-the-art, 3-D numerical hydrodynamic model called CH3D. The model results also were used to drive a separate water quality model. In order to calibrate and verify the CH3D model, comprehensive field data were collected in the summer of 1987. These included surface elevation data measured at eight locations, current measurements with in situ current meters deployed at nine stations, current velocity profile measurements taken at major entrances to the harbors and interior channels, and a drogue study. For the numerical simulation, a variable, rectilinear grid containing 12,032 cells was used in the horizontal. In the vertical, a stretching mechanism was used to represent the bathymetry smoothly. Several sensitivity tests were conducted to determine model response to variation of key model parameters. On the basis of the tests, three cells were used in the vertical. The period from 7 to 11 August 1987 representing a large spring tide was used for model calibration, and the period from 19 to 23 August 1987 representing a mean tide was used for verification. In each case, the model was started from rest and forced with measured surface elevations at the open boundary and wind stresses, computed from measured wind data, at the free surface. Comparison of model results with observed surface elevations and currents indicated the model reproduced prototype behavior throughout the harbor complex and overall calibration and verification were successful. In order to demonstrate model use in investigating plan conditions, a plan condition known as Scheme B, Phase 1 was tested in the model. Model bathymetry was modified to represent plan conditions. Base conditions adopted for comparing the plan with existing conditions were the two periods used for model calibration and verification. Comparison of model results for plan with existing conditions indicated tidal ranges were maintained and there were no noticeable differences in phase. Discharge into the system was reduced by an amount equivalent to the reduced harbor surface area (about 10 percent). Velocity magnitude and direction were changed at specific locations. Peak flood and ebb velocities at Angel's and Queen's Gates were reduced up to 50 and 40 percent, respectively, for a large spring tide condition . Net circulation in the Inner Harbor showed a tendency to reverse under plan conditions. NOTE: This file is large. Allow your browser several minutes to download the file.
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