Los Angeles and Long Beach Harbors Model Enhancement Program: Long Waves and Harbor Resonance Analysis

Abstract

Abstract : Long period wave data have been collected at an offshore wave gauge and seven harbor gauges for over 8 years in the Los Angeles/Long Beach Harbor region. These data are being used in studies for the design of expansion of the harbors. In particular, the data have been used to select long period spectra for reproduction in a physical model of the harbors. The analysis of prototype wave data indicated correlation between the long wave spectrum and the short wave spectrum. Information was examined to determine the effect of the source of the short period waves (Southern Hemisphere swell, hurricanes, or winter storms, typically from the west) on the nature of the long period component of the waves. Relationships between the origin of the wave energy and long wave period were determined. Wave statistics were used to interpret effects of the energy level on the wave transformation into the harbors and correlate long wave and short wave spectra. Examination of a 5 to 22 sec short wave period and a 30 to 400 sec long wave period indicated correlation of smaller short wave periods with smaller long wave periods, and larger short wave periods with larger long wave periods. Observations of moored ship motion level was correlated to long wave energy in a harbor basin.