*************** EXAMPLE PROBLEM 6*************** 



7 8 



GIVEN ; A bay with a surface area of 1.86 x 10 square meters (2 x 10 square 



feet) and an average depth of 6.1 meters (20 feet) is located on the 

 Atlantic coast. The tide is semidiurnal (T = 12.4 hours), vath a spring 

 range of 1.34 meters (4.4 feet), as given by the National Ocean Survey Tide 

 Tables (National Oceanic and Atmospheric Administration, 1976). An inlet 

 channel, vAiich will be the only entrance to the bay, is to be constructed 

 across the barrier beach which separates the bay from the ocean. The inlet 

 is to provide a navigation passage for small vessels, dilution vater to 

 control bay salinity and pollution levels, and a channel for fish migra- 

 tion. The channel is to have a design length of 1,097 meters (3,600 feet) 

 with a pair of vertical sheet pile jetties that will extend the full length 

 of the channel. 



FIND : If the channel has a depth below MSL of 3.66 meters (12 feet) and a 

 width of 183 meters (600 feet), what are the maximum flow velocity, bay 

 tidal range, and the volume of water flowing into and out of the bay on a 

 tidal cycle (tidal prism) for a tide having the spring range? 



SOLUTION ; Assume kg„ = 0.1 , kg^= 1.0, and f = 0.03; B = 183 meters, 

 and d = 3.66 meters. 



Ag = Bd = 183 (3.66) = 669 square meters (7,200 square feet) 



^a 669 



^ = (B+ 2d) = (183+ 2(366)) = ^'^^ '"^'"" ^^^'^'' ^^^^^ 



F = k,„ + k^^ + § = 1.0 + 0.1 + "-"^^^g;^^ = 3.43 



^ ^s^&F ^ (1.34/2) (1.86) (10^) 3.43 ^ 

 1 2LAg 2(1097) (669) 



and 



2ii /l097(1.86) 10^ 



= 0.25 



2 T Vs^c 12.4(60) (60) \ 9.8 (669) 

 From Figures 4-75 and 4-76, with the above values of K, and K^ 



and 



V^ = 0.66 



0.78 



Therefore, from equation (4-64) 



V = 



m A^T 



4-165 



