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Main parameters for an empirical formula
7.2 Main parameters for an empirical formula
In a first step, the different existing scour formulae, mentioned in section 3.5 were used to determine
a set of parameters influencing the scour process (see table 7.1).
FORMULA
Fargue (1868)
van Bendegom (1947)
Engelund (1974)
Bridge (1976)
Kikkawa et al. (1976)
Reindl (1994)
Zimmermann (1978)
Falcon & Kennedy (1983)
Odgaard (1986)
Bazilevich (1982)
MAIN PARAMETERS
R c
⁄ B , bed roughness, V
Fr d
7 ⋅ tanφ
11 ⋅ tanφ
= cst
= cst
Fr d
, V∗ ⁄ V , n
Fr d
, V∗ ⁄ V , n, G S
Fr2
d
, n
Fr d
, n, θ , p
Fr d
, n, θ
h m
⁄
h max
Peter (1986) ⁄ B , σ, h m
⁄ B , Fr
Table 7.1:
List of parameters used in existing scour formulae
R c
The following parameters were correlated with the maximum scour depth in the first and second
hole, with the maximum scour over the bend 1 as with the relative scour h s ⁄ h m (computed in the
inlet reach) and with the maximum transversal bed slope tan( β max ):
⁄ B , Fr d , V, V∗ ⁄ V , θ, tanφ.
R c
The sediment saturation G S , used by Reindl was not used because an estimation of this parameter
is difficult or almost impossible in engineering practice. Mannings friction factor n and the porosity
p are not correlated since they were constant for the tests ( p) or not independent of the other
parameters ( n ).
Additional parameters were added to obtain a wide range of characteristics , which could have an
influence on the scour process. The test parameters as well as the obtained correlations are given
in the following table (Table 7.2). All the correlations are given for the data set without macroroughness,
including Peter’s tests.
1. The maximum scour h 12
was sometimes located in the upstream and sometimes in the downstream
scour.
EPFL Ph.D thesis 2632 - Daniel S. Hersberger November 9, 2002 / page 151