1 Introduction 
Background 
Los Angeles and Long Beach Harbors (Figure 1) are located adjacent to 
each other in San Pedro Bay on the southern California coast. They share a 
common breakwater system. Ocean waters circulate into, out of, and between 
both harbors due to the action of tides and wind. Angel’s Gate and Queen’s 
Gate are the two major entrances to the harbors, in addition to an opening at 
the eastern end. As these ports respond to the expansion of oceanborne world 
commerce and propose plans to accommodate future needs (including deeper 
channels and landfills), environmental impacts (including impacts on 
circulation) must be examined. Approaches to examine plan impacts include 
modeling, and in the cases of Los Angeles and Long Beach Harbors, there 
have been several numerical model studies of tidal circulation (Chiang and 
Lee 1982, Seabergh and Outlaw 1984, Seabergh 1985). Most of the previous 
numerical circulation studies were performed using depth-averaged models 
such as WIFM (Butler 1980) and using only tides for forcing. Recently, the 
ports, together with the U.S. Army Engineer District, Los Angeles and the 
U.S. Army Engineer Waterways Experiment Station (WES), embarked on a 
Harbors Model Enhancement (HME) Program. The program is outlined in 
Table 1. As a part of HME, the Coastal Engineering Research Center 
(CERC) of WES calibrated and verified a three-dimensional (3D) 
hydrodynamic model with field data. The model was forced with tides and 
wind, using measured surface elevations at the offshore boundary. The results 
of these efforts are described in Vemulakonda and Butler (1989), and CERC 
(1990). As a follow-up to this work, the effects of different winds on 
circulation in the harbors were examined (using the same 3D numerical 
hydrodynamic model and the same 1987 harbor configuration). This report 
describes the results of these model simulations. 
Chapter 1 Introduction 
