(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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