SAM.hyd also has the ability to determine whether or not riprap is required.
The program evaluates the calculated bed shear stress and the Shield's critical
value. If the calculated bed shear stress is greater than Shield's critical value,
SAM.hyd will notify the user that riprap is required. The user may then alter the
data file to request riprap calculations.
Regime channel dimensions, determined using the Blench (1970) equations,
can be calculated as a function of bed material gradation, bank consistency, and
bed-material sediment concentration.
SAM.hyd Options
SAM.hyd can solve for any one of the variables in the uniform flow equation.
Water discharge is usually the dependent variable (equation 2-1). However,
SAM allows any of the variables on the right hand side to become the dependent
variable, except side slope, z. SAM.hyd inspects each input record type in a data
set and determines which variables have been prescribed. The variable omitted
becomes the dependent variable.
Q = f(D, n,W, z, S)
Equation 2-1
where
Q = water discharge
D = water depth
n = n-value
W = bottom width
z = side slopes of the channel
S = energy slope
Most of the major calculation options in SAM.hyd rely on the above
relationship. For SAMwin, all variables can be prescribed. The user must select
the variable to be calculated: normal depth, bottom depth, energy slope,
hydraulic roughness (n-values and ks values), and water discharge. Flow
distribution is calculated each time the uniform flow equation is solved, and can
be requested during any of the calculations.
Other parameters are also calculated when the uniform flow equation is
solved. In SAM.hyd, composite hydraulic parameters can be calculated by four
options: alpha method, equal velocity method, total force method and
conveyance method.
7
Chapter 2
Theoretical Basis for SAM.hyd Calculations
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