where:
=
4.780 in SI units
Ku1
Ku1
=
1.606 in English units
=
10.846 in SI units
Ku2
=
3.306 in English units
Ku2
qB
=
Metric-tons/day/meter (Tons/day/foot)
Water discharge quantity determining the bed-load transport, m3/s (cfs)
=
Qb
Total water discharge m3/s (cfs)
Q
=
D90, Dm
=
In millimeters (both SI and English units)
The quantity Dm is the effective diameter of the sediment given by
ΣipiDsi
Dm =
(4.20)
100
where:
=
Percentage by weight of that fraction of the bed material with geometric
pi
mean size, Dsi
The term nb is the Manning's roughness coefficient for the bed of rectangular channels
2/3
n w 3 / 2
2y
1 -
nb = n1 + o
(4.21)
n
W
and for trapezoidal channels
2y (1+ H2 )1/ 2
2/3
nw 3 / 2
nb = n1+ o
1-
(4.22)
s
W
n
where:
n, nb, nw
=
Roughness coefficients of the total stream, of the bed, and of the
banks, respectively
=
Horizontal side slope related to one unit vertically
Hs
W
=
Bottom width
The ratio Qb/Q for rectangular channels is given by
Qb
1
=
(4.23)
3/2
Q
n w
2y
1+ o
W
nb
4.12
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