Environmental Engineering Reference
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Table 7.2. Comparison of the total amount of sedimentation and the relative sedimentation
for the three predictors as a function of the discharge and the relative discharge.
Discharge m
3
/s
25.75
23.175
20.66
19.055
Rd discharge
1
0.9
0.8
0.74
Inflow sediment (m
3
)
20023
18021
16129
14817
Volume sedimentation (m
3
)
Brownlie
0
3207
6090
6810
Rd sedimentation
0.00
0.18
0.38
0.46
Volume sedimentation (m
3
)
Acker-White
7445
8313
8664
8414
Rd sedimentation
0.37
0.46
0.54
0.57
Volume sedimentation (m
3
)
Engelund-Hansen
5498
7990
9043
8792
Rd sedimentation
0.27
0.44
0.56
0.59
0.60
0.50
0.40
0.30
0.20
0.10
Figure 7.4. Relative sediment
deposition as a function of the
relative discharge at the end of
the simulation period for Case 1
according to the Ackers-White,
Brownlie and Engelund-Hansen
predictors respectively.
0.00
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
Relative discharge
A-W
Br
E-H
Figure 7.4 shows the relative deposition as a function of the relative
discharge Rd of 1, 0.90, 0.80 and 0.74, respectively. At the end of the sim-
ulation period the difference between the relative deposition for Brownlie
and for the other two predictors is smaller for Rd
0.74 than for the
larger Rds. The comparison of the sedimentation for the Ackers-White
and Engelund-Hansen predictors has been based on their equilibrium
concentration for the design discharge of 25.75 m
3
/s, which means that
the relative deposition is larger than zero for a relative discharge of 1,
specifically in Case 1. The comparison has not been extended to the
larger discharges for which the incoming concentration (according to
the Engelund-Hansen predictor) are the same for uniform flow at that dis-
charge. The water depth, discharge and related velocity will all be different
for the three predictors and a comparison will be more demanding.
=
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