Environmental Engineering Reference
In-Depth Information
CHAPTER 5
Sediment Transport Concepts
5.1 INTRODUCTION
From a mathematical point of view, the interrelation between specific
water flow and sediment transport conditions for a one-dimensional
phenomenon without changes in the shape of the cross section can be
described by the following equations (Cunge et al., 1980):
-
Continuity equation for water movement
:
∂A
∂t
+
∂Q
∂x
=
0
(5.1)
-
Dynamic equation for water movement
:
∂y
∂x
+
v
2
C
2
R
+
∂z
∂x
+
v
g
∂v
∂x
+
1
g
∂v
∂t
=
0
(5.2)
-
Friction factor predictor
which can be given as a function of:
C
=
f
(
d
50
,
v
,
y
,
S
o
)
(5.3)
-
Continuity equation for sediment transport
:
p
)
B
∂z
∂Q
s
∂x
=
(1
−
∂t
+
0
(5.4)
-
Sediment transport equation
which can be given as a function of:
Q
s
=
f
(
d
50
,
v
,
y
,
S
o
)
(5.5)
where:
Q
s
=
sediment discharge (m
3
/s)
B
=
bottom width (m)
d
50
=
mean diameter of sediment (m)
p
=
porosity (dimensionless)
z
=
bottom level above datum (m)
v
=
average velocity (m/s)
y
=
water depth (m)
S
o
=
bottom slope (m/m)
R
=
hydraulic radius (m)
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