Repository logo
 

Los Angeles and Long Beach Harbors model study. Report 3, Analyses of wave and ship motion data

Loading...
Thumbnail Image

Date

1976-07

Authors

Durham, Donald L. (Donald Lee)
Thompson, Jack K.
Outlaw, Douglas G.
Crosby, Leroy G.

Journal Title

Journal ISSN

Volume Title

Publisher

Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)

Abstract

Description

Technical Report
Abstract: This report describes the procedures and presents the results of analyses of prototype ship motion and wave data collected in the Los Angeles and Long Beach Harbors during a 1-yr data acquisition program. The wave data were collected by the U.S. Army Engineer Waterways Experiment Station (WES) and the ship motion data were obtained by personnel of the Ports of Los Angeles and Long Beach under the direction of the U.S. Army Engineer District, Los Angeles. All analyses of these data were performed by WES. This report is the third of a series to be published under the general title "Los Angeles and Long Beach Harbors Model Study." The model study has four major objectives : (A.) to determine incidence and severity of troublesome oscillations in the present harbor complex, (B.) to investigate tidal circulation characteristics of the present and proposed harbors, (C.) to determine the optimum plan for future expansions to provide safe and economical berthing areas, and (D.) to analyze the effects of proposed expansions on the existing harbors. Prototype data are required to define existing wave and tidal conditions and mooring problems in the existing harbors and for use in various physical and numerical modeling efforts of this study. Acquisition procedures, instrumentation, and collected prototype data have been published in Reports 1 and 2 of this series and analysis of tidal data in published in Report 5. In the ship motion analyses, observations of ship characteristics, movement, and mooring line configurations/characteristics are statistically analyzed for various time distributions and concurrences of movement. For various ships and mooring configurations in the East Channel of Los Angeles Harbor, a numerical analysis of moored ship response to wave excitation is conducted to define the periods or frequency ranges of maximum surge response. In the analysis of wave data, estimates of wave energy for wave periods ranging from 15 sec to 3 hr are calculated from the prototype wave data by spectral analyses. Time-dependent spectral estimates are calculated for 10 time periods during which concurrences of medium and/or heavy ship movement occurred. From such spectral techniques, frequency bands containing significant energy levels are identified for 15 wave gage locations in the two harbors. In addition to identifying characteristic frequency bands of wave energy for each gage, the time variation of energy levels within each frequency band and the distribution and/or penetration of swell throughout the harbors are estimated. Observations of adverse ship motion are correlated with time variations of energy levels in characteristic frequency bands. Subjective analyses of analog wave records are conducted to provide indications of frequency of occurrence and wave- height distributions for previously identified wave periods having maximum energy (wave heights). NOTE: This file is large. Allow your browser several minutes to download the file.

Keywords

Long Beach Harbor (Calif.), Energy spectra, Los Angeles Harbor, Surge, Ship motion, Water waves, Harbors, Ports, California

Citation

Collections

chat loading...