Environmental Engineering Reference
In-Depth Information
h
=
water depth (m)
kinematic viscosity (m
2
/s)
ν
=
F
gr
=
mobility parameter (dimensionless)
A
=
value of
F
gr
at the nominal, initial movement
G
gr
=
transport parameter (dimensionless)
c
=
coefficient in the transport parameter
G
gr
m
=
exponent in the transport parameter
G
gr
n
=
exponent in the mobility parameter
F
gr
u
∗
=
shear velocity (m/s)
=
V
mean velocity (m/s)
q
s
=
total sediment transport per unit width (m
2
/s)
A.3 BROWNLIE METHOD
The Brownlie method (1981) to compute the sediment transport is based
on a dimensional analysis and calibration of a wide range of field and
laboratory data, where uniform conditions prevailed. The transport (in
ppm by weight) is calculated by:
F
g
cr
)
1
.
978
S
0
.
6601
R
d
50
−
0
.
3301
q
s
=
727
.
6
c
f
(
F
g
−
(A.9)
- grain Froude number:
V
F
g
=
(A.10)
1)
gd
50
]
0
.
5
[(
s
−
- critical grain Froude number:
0
.
5293
o
S
−
0
.
1405
σ
−
0
.
1696
s
F
g
cr
=
4
.
596
τ
∗
(A.11)
- critical shear stress
0
.
06(10)
−
7
.
7
Y
τ
∗
o
=
0
.
22
Y
+
(A.12)
The value of
Y
follows from:
(
√
s
1
R
g
)
−
0
.
6
Y
=
−
(A.13)
- grain Reynolds number:
(
gd
50
)
0
.
5
31620
ν
R
g
=
(A.14)
where:
c
f
=
coefficient for the transport rate
c
f
=
1 for laboratory conditions
c
f
=
1.268 for field conditions
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