TV 



1/ \ 



V 



^V 



l«£-l 1 1 1 I : I I •* 1 ■ 



0.125 0.063 0.031 0.016 008 0.004 0.002 0.001 0.0005 

 d, (mm) 



14.1 3.5 0.88 0.22 0.055 0.014 0.0034 

 v s (mm/s) 



Figure 7. Composite settling velocity and size-frequency histogram of 

 suspended sediment obtained at Dillingham Harbor, Alaska, May to 

 September 1974. Histogram shows mean frequency per v g or d 

 unit shown on the abscissa. v g - particle settling velocity; 

 d = particle diameter in millimeters. 



SOLUTION: 



(a) Step 1 — Determine the Sediment Mass that Enters the Basin Each Tidal 

 Cycle . The mean concentration of suspended sediment, c, that enters the 

 basin during the floodtide cycle is 



i + c (2) °* 8 + °' 2 



=0.5 kilogram per cubic meter (11) 



The value of k g , the correction factor for a time-varying concentration of 

 sediment entering the basin (from eq. 2), is 



k = 4 



h^).,^) 



12.4 



= -0.19 per hour 



(12) 



The sill elevation, z , is 



z„ = 1.5 = — meters 



(13) 



where a„ = 6 meters. 



15 



