3-73 



To further put the magnitude of the discharge in perspective, 

 we calculated the total kinetic energy (KE) of the discharge, which can 

 be calculated for one phase of the tide as: 



KE = 1/2 mv^ 



where m equals the mass of the water entrained over 6.2 hours and v 

 equals the discharge velocity. 



o 1 ^ 



KE = 1/2 • 3.92 X 10 Kg • 9 . 3 m /sec = 1.8 x 10 ergs 



We then calculated the potential energy (PE) of the tidal prism, which 

 is discharged as, kinetic energy in tidal currents and friction: 



PE = mgh 



where m equals the mass of the tidal prism, g equals the acceleration 

 due to gravity and h is the integrated head of the tide above mean low 

 water. 



PE = (5.0 X 10 Kg) • (9.8 m/sec ) • (0.95 m) = 4.66 x lO"""^ ergs 



Thus, the mechanical energy added to the harbor circulation by the 

 Harbor Station's circulating pump system is approximately 4% of the 

 energy attributable to the rise and fall of the tides. 



Flow-away velocities of the cooling water discharge plume 

 discussed above result in currents persisting primarily in a narrow 

 band, 15 to 30 m wide. They do not pose any problem to larger vessels, 

 nor any direct hazard to smaller craft, but can cause some deflection of 



small craft from their courses. For example, a boat traveling at 10 



2 

 knots (5.1 X 10 cm/sec) might drift sideways 4-5 m while passing across 



the full width of the current zone. This is a minor effect when com- 

 pared to the effect of a strong crosswind. Boats close together are not 

 driven together by the current, since they are both affected by it. 



