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Title: Los Angeles and Long Beach Harbors model study. Report 4, Model design
Authors: United States. Army. Corps of Engineers. Los Angeles District.
Outlaw, Douglas G.
Durham, Donald L. (Donald Lee)
Chatham, C. E. (Claude E.)
Whalin, Robert W. (Robert Warren)
Keywords: Harbor oscillations
Los Angeles Harbor
Prototype data
Hydraulic models
Water waves
Long Beach Harbor
Wave generation
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-75-4 rept.4.
Description: Technical Report
Abstract: This report describes the design of the Los Angeles and Long Beach Harbors hydraulic model for investigation of harbor oscillation characteristics of the existing harbor and for evaluation of various proposed harbor modifications. The effects of wave refraction, diffraction, viscous friction, wave reflection, wave transmission through the harbor breakwaters, wave filters, and wave absorbers were considered. Wave generator design, automated model data acquisition and control, and model data analyses are also described. This report is the fourth in series Technical Report H-75-4 published under the general title "Los Angeles and Long Beach Harbors Model Study." A model distortion ratio of 1:4 and a vertical scale ratio of 1:100 (1:400 horizontal scale ratio) were selected to minimize the model area and to provide a vertical scale ratio where accurate model wave measurements could be assured. The model reproduces approximately 253 square miles of prototype area. Model limits were selected to enclose a strong convergence zone seaward of the harbor breakwater. Adjustment of the initial generated wave-front position in the model was necessary to compensate for model distortion and the maximum model depth of -300 ft mllw. The electrohydraulic wave generator used in the model study is composed of 14 separate 15-ft units for a total wave generator length of 210 ft and is capable of (A.) generating waves with a prototype period ranging from 15 to 600 sec, (B.) generating a wave with small variation in period and height between units, (C.) defining resonant response over a narrow period band, (D.) generating a variable wave height along the wave front , and (E.) generating a curved wave front. Performance requirements for the wave generator include : (A.) the amplitude error of the wave-paddle stroke for each unit must be less than 1 percent and (B.) the phase lag of the wave-paddle response from the electronic command signal between each of the 14 units must be less than 4 degrees. The four subsystems of the automated model data acquisition and control system include: (A.) digital data recording and controls, (B.) analog recorders and channel selection circuits, (C.) wave sensors and interfacing equipment, and (D.) wave generator units and control equipment. Model wave record analyses include the capacity for determination of : (A.) average, root mean square, and significant wave height and (B.) average period. Procedures for Fourier analysis and least-squares harmonic analysis of the wave record are also available. The hydraulic model can be used in a predictive mode to evaluate various proposed modifications to optimize the modifications from both a cost and functional standpoint. Potential future uses of the model include studies of (A.) dispersion of effluent from specific outfalls in the harbor complex, (B.) tsunami waves, (C.) effects of various coastal structures from Point Fermin to Huntington Beach, (D.) effects of artificial offshore islands or landfill seaward of the existing harbor breakwater on tidal circulation and wave conditions, (E.) tidal circulation in areas such as Huntington Beach, Bolsa Chica Wildlife Reserve, Alamitos Bay, etc., (F.) effect of various future harbor modifications on tidal circulation and wave conditions, (G.) studies of the physical environment in the harbor and surrounding areas, and (h.) wave and tidal circulation studies of the proposed Downtown and Queensway Marinas.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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