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Chapter 7 Performing Channel Flow Analysis
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If you select the SEDTRA module, you must enter a value for the parameter x
for the determination of the diameter used in the determination of incipient
motion conditions. The default value for x is 0.5.
If the Wu et al. formula is used, you must define a value for the coefficient χ
that accounts for vegetation effects. The default value is 1.0, meaning no
correction for the presence of vegetation.
Please consult the CCHE1D Technical Manual for detailed information on the
implementation of the above equations. Keep in mind that each equation will
yield different results, and not all equations may be applicable to a particular
problem.
Bank Stability Analysis
After you choose a sediment transport capacity equation, you can disable the
Bank Erosion and Stability Analysis of CCHE1D. If it is disabled, CCHE1D
will not compute bank erosion and potential bank mass failures.
Bed Load Adaptation Length
The bed load adaptation length is one of the most important parameters in the
numerical computation of sediment transport using the non-equilibrium
approach. The method used to define this parameter can affect the magnitude
of transport that occurs in a channel, and it can influence the numerical
stability of the solution. Please consult CCHE1D’s Technical Manual for a
discussion on this parameter. Currently, CCHE1D offers four approaches for
the determination of the adaptation length:
ƒ Function of Alternate Bar Length
ƒ Function of Dune Height
ƒ Function of Reach Length
ƒ User-specified value.
The default option is “Function of Alternate Bar Length.”
Suspended Load Adaptation Coefficient
The Suspended Load Adaptation Coefficient α, which is used to calculate the
adaptation length, can be determined by either:
ƒ Armanini and di Silvio Method (1998), or
ƒ User-specified value
The default option for this parameter is a constant value of 0.5. Please consult
the CCHE1D Technical Manual for more information on the subject.