Van Rijn
is based on Van Rijn (1984 a, b). Some of the modifications
made by Spasojevic and Holly (1994) for CH3D-SED are
incorporated. The most significant change is the multiple-grain
grain size treatment. A hiding factor is applied to the bed load
transport, but not the suspended load transport. Shield's
parameter is calculated using Van Rijn's equations. The
suspended sediment concentration profile is calculated using
equations proposed in Van Rijn's paper (1984b). Recommended
use is for grain sizes between 0.1 and 0.5 mm.
Yang (1973, 1984) is a version of Yang, D50, which has been modified, at
WES, for multiple grain size calculations in sand and gravel bed
streams (less than 10 mm).
Yang, D50
is a single grain size function for sand and gravel transport in
streams and small rivers.
This is not an exhaustive list of transport functions. These were selected
based on both corporate experience and recommendations from the literature.
There is no implication that those not selected are deficient. The objective in
SAM.sed was to provide designers with a "few" acceptable methods whose use
could be supported. The criteria for selection were
a. to cover a broad range of particle sizes;
b. to cover a broad range of hydraulic conditions;
c. to calculate sediment transport by partitioning the mixture into size
classes and summing the rate of each to get the total, except when d50
functions are requested; and
d. to have a history of being reliable when used within the range of data
for which each was calibrated.
The Brownlie function is included here because it is used in the analytical
method for calculating channel width, depth and slope in SAM.hyd. It is a single
grain size function.
Calculations
The functional form for sediment transport equations is
GS i = (V, D, S e , Be , d e , ρ s , G sf , d s , ib , ρ f ,T)
Equation 3-1
50
Chapter 3
Theoretical Basis for SAM.sed Calculations
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