Numerical Hydrodynamic Modeling in Support of Water Quality and Ship Simulation Models in Los Angeles Harbor.

Abstract : A previously calibrated three-dimensional, numerical circulation model for Los Angeles Harbor has been used to assess the hydrodynamic impact of proposed ship channel dredging and landfill at Pier 400 in the Los Angeles Harbor. Supplemental calibration and verification were conducted for both coarse and fine model grids used in support of water quality and ship simulation models, respectively. Results of numerical modeling show that the water surface elevation in the harbor was very little affected by either the deepening of the channel or by the construction of Pier 400. Flow velocities, on the other hand, changed. Flow velocities were mainly forced to conform to the shape of Pier 400, which is proposed to be placed in the middle of outer Los Angeles Harbor. Overall velocity magnitudes are slightly lower for the proposed deeper channel depth versus the existing shallower depth. Critical wind forcings (20-knot speed from the west southwest and southeast directions) were simulated in order to predict the highly transient current velocity in the navigation channel. Results indicate that the wind's effect can be significant. Nevertheless, current velocities are generally under 1 knot in the harbor channel, except for extremely high wind conditions.