(4.27)
iB qB
and the suspended sediment load is given by
(4.28)
isqs
and the total bed material discharge is
iT qT = is qs + iB qB
(4.29)
and finally
Q T = ΣiT qT
(4.30)
where iT, is, and iB are the fractions of the total, suspended and contact bed sediment
discharges qT, qs and qB for a given grain size Ds. The term QT is the total bed sediment
transport. The suspended sediment load is related to the contact load because there is a
continuous exchange of particles between the two modes of transport.
With suspended sediment load related to the contact load, Equation 4.29 becomes
iT qT = iB qB (1 + PEI1 + I2 )
(4.31)
where:
PE = 2.3 log (30.2y o / ∆)
(4.32)
I1 and I2 are integrals of Einstein's form of the suspended sediment Equation 4.12
φ*iB γ s
iB qB =
(4.33)
1/ 2
ρ
1
ρ - ρ gD 3
s
s
and
=
Unit weight of sediment
γs
=
Density of the water
ρ
=
Density of the sediment
ρs
g
=
Gravitational acceleration
=
Dimensionless sediment transport function = f(ψ*) given in Figure 4.5
φ*
ψ * = ξY(β / β x )2 ψ = ξY(log10.6 / β x )2 ψ
(4.34)
ρ - ρ Ds
ψ′ = s
ρ R′ S
(4.35)
b f
ξ
= Correction factor given as a function of D / X in Figure 4.6
s
4.14
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