outflow through the east breakwater gap (Plate 125). Consequently, the flow 
at the Middle Harbor (Plate 123) is directed east. In the later regime, there is 
outflow through Angel’s and Queen’s Gates and inflow through the east 
breakwater gap, with the result that flow at the Middle Harbor is directed 
west. During peak winds, net flow through the Middle Harbor is four times 
the normal eastward flow and maximum ebb discharge at the east breakwater 
gap is doubled to 300,000 cfs. The longer term effect on discharges for Case 
3, when compared to Case 2 (for example, Plate 125 compared to Plate 77), 
results because of the slower decline in wind speed and the steady wind 
direction for Case 3. 
Time series of velocity (Plates 126-140; plots for Gages 18 and 19 are not 
included) show that at all three entrances, velocity magnitude increases at all 
three layers. Strong surface currents (order of 3 to 4 ft/sec) are directed in. 
Dramatic velocity change is observed at the entrance to the West Basin 
(Gauge 3, Plates 132-134) also. Tidal elevation plots (Plates 141-145) show 
no significant change in surface elevation. Snapshots of velocity vectors 
(Plates 146-157) are included. Figure 24 shows the current pattern at all three 
levels at 5278 hr. In general, the snapshots show that during peak winds, 
surface currents in the Outer Harbor are southward whereas bottom and 
mid-depth currents are northward. In general, some minor effects due to 
reflections from the offshore boundary may be present in model results for the 
later part of the simulation. They do not change the main conclusions 
reported here. 
Effect of Wind on Circulation in Ship Basins 
As shown above, wind events can have significant effects on circulation in 
harbors. However, it is important to note that everyday wind conditions can 
contribute to improved circulation in closed-end ship basins. Figure 25 
compares a no-wind condition with the calibration condition, which includes 
typical winds from the west-southwesterly direction. The example shown is 
for Scheme B, Phase 1 of the Operations, Facilities, and Infrastructure 2020 
Requirements Study. Surface currents are aligned with the wind. Examining 
some of the closed slips, especially the one adjacent to Pier 300, surface 
currents are into the basin, while mid-depth and bottom currents are exiting 
the basin, indicating a turning over of the water mass. In contrast, for the 
no-wind situation, currents are slower and unidirectional. 
Chapter 5 Model Simulations 
33 
