Environmental Engineering Reference
In-Depth Information
In the comparison, the Ackers-White, Brownlie and Engelund-Hansen
methods have been applied to predict the total sediment transport under
equilibrium conditions. The three procedures have been compared on a
relative basis. The sediment transport from the Brownlie data set is com-
pared with the predicted sediment transport calculated by one of these
three procedures. Then the predictability of each procedure is evaluated
on the basis of well-predicted values within a certain accuracy range.
For a given error factor (
f
) the upper and lower range are given by:
measured value
f
≤
predicted value
≤
measured value
∗
f
(5.117)
number of well predicted values
total values
accuracy
=
(5.118)
The comparison (Figure 5.28) shows that the reliability of the predictors
will improve when a correction factor is applied to incorporate the effect
100
Brownlie predictor
80
60
40
20
0
1.25
1.5
1.75
2.0
2.5
0
Error factor
100
Ackers-White predictor
80
60
40
20
0
0
1.25
1.5
1.75
2.0
2.5
Error factor
100
Engelund-Hansen predictor
80
60
40
20
0
0
1.25
1.5
1.75
2.0
2.5
Error factor
Procedure 1
Procedure 2
Procedure 3
Figure 5.28. Evaluation of the
three sediment transport
predictors (Paudel, 2010).
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