3
kr
2
′
Rb = Rb
k′
r
and
n
dm = ∑ fi di
i =1
where:
f i = fraction of size class "i" in bed
d i = geometric mean diameter of size class "i" in bed.
Calculating sediment discharge and concentration
A typical cross section, with the critical hydraulic parameters labeled, is
shown in Figure 2.9. The concentration calculated from the sediment transport
equation applies only vertically above the bed. Total sediment transport in
weight per unit time is calculated by the following equation:
Qs = γ C B D V
Equation 2-54
where:
Qs = sediment transport in weight/time
B = base width
Qs
C=
Equation 2-55
0.0027 Q
An average concentration for the total discharge is then calculated:
where:
C = concentration using the total discharge, in ppm
Qs = sediment transport in tons/day
Q = discharge in cfs
41
Chapter 2
Theoretical Basis for SAM.hyd Calculations
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