The sediment-concentration correction coefficient is K = 0.65 when these 

 values are applied to Figure 2. Using equations (5) and (6), the total mass 

 of sediment calculated to be carried into the harbor is 



M = c 



^H 



a s K = (0.5)(35,000)(6)(0.65) = 68,250 kilograms (14) 



per tidal cycle 



(b) Step 2 — Find the Sediment Mass Deposited in the Harbor. Since the 

 sill elevation of Dillingham Harbor is not zero, and the concentration of 

 sediment entering the harbor varies through the floodtide (inflow) cycle, 

 corrections must be made for those factors when using Figure 3. However, 

 the settling velocity frequency distribution must first be calculated. This 

 is done for each size-interval shown in Figure 7. The frequency value, f, 

 references that part of the sediment mass with a settling velocity in a 

 single size interval (see Table). 



Table. Part of sediment deposited in harbor basin. 



"s(mm) 



f 



P 



P s 



p sb 



f x P sb 



0.125 







1.0 



1.0 



1.0 







0.063 



0.05 



1.0 



1.0 



1.0 



0.05 



0.031 



0.18 



0.99 



0.99 



0.995 



0.18 



0.016 



0.46 



0.84 



0.885 



0.92 



0.42 



0.008 



0.17 



0.33 



0.345 



0.375 



0.06 



0.004 



0.12 



0.07 



0.05 



0.06 



0.01 



0.002 



0.02 



0.01 



0.01 



0.01 







0.001 























Total 



0.72 ! 



For each sediment-size interval the P value (Fig. 3) is corrected for 

 a sill elevation of a s /4 (Fig. 4), and further corrected for the time- 

 varying concentration of sediment which enters the harbor (Fig. 5; eq. 6). 



These corrections are shown in the Table. The sum of 



sb 



values shows 72 



percent of the sediment that enters the basin will be deposited. The mass 



of sediment deposited, 

 cycle. 



M 



^ (using eq. 9), is 49,000 kilograms per tidal 



(c) Step 3 — Find the Shoaling Rate in the Harbor . From equation (8) the 

 is 0.29, and using equation (9), n^ is 790 kilograms per 



value of V g j 



cubic meter. The summer season shoaling rate, 



tidal cycle (eq. 10). 



is 0.0030 meter per 



16 



