Environmental Engineering Reference
In-Depth Information
The same conditions are also used to compare all the three sediment
predictors, namely Ackers-White, Brownlie and Engelund-Hansen. For
the same design characteristics as presented in Case 1, the sedimen-
tation in the canal has been evaluated for the three sediment transport
predictors. The equilibrium concentration according to the Ackers-White
and Engelund-Hansen predictors for the design discharge and a sediment
diameter of 0.15 mm (see Case 1) are smaller than for Brownlie, namely
41 and 56 ppm. This means that sediment deposition according to these
predictors will already occur for the design discharge of 25.75 m
3
/s and
an incoming sediment concentration of 100 ppm. The effect of a larger
sediment diameter on the sediment deposition is presented in Figure 7.9.
The figure shows that the changes in the relative sediment size have an
evident impact on the deposition and that the deposition will increase in
the same way for all three predictors.
0.60
0.50
0.40
0.30
0.20
0.10
0.00
1.0
1.1
1.2
1.3
1.4
1.5
1.6
Relative diameter
Brownlie
0.60
0.50
0.40
0.30
0.20
0.10
Figure 7.9. Relative sediment
deposition after 90 days as a
function of the variation in
relative median sediment size
for the three predictors
(Q
0.00
1.0
1.1
1.2
1.3
1.4
1.5
1.6
Relative diameter
A-W
Br
E-H
=
25.75 m
3
/s and
c
=
100 ppm).
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