Environmental Engineering Reference
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Read data from
water flow
caculation
Calculate the sediment transport
capacity for the entire reach
For i = 1 to total lenght of the reach
Is there
equilibrium
condition?
Ye s
No
No
Ye s
C(i) = Ce
Deposition?
Yes
Entrainment?
Figure 6.3. Flow diagram of
SETRIC for calculating the
sediment transport in the main
canal and lateral canals during a
time step.
Compute the sediment transport
No
C(i) = C(i-1)
Next time step
- The model simulates the total sediment load and not the bed load and
suspended load separately. If a structure has a raised crest then it might
trap a part of the bed load upstream of the structure. Only the whole
suspended load part will move downstream of the structure. Out of the
total load the suspended load-carrying capacity of the canal is calculated
using the following relation (Méndez, 1998):
q
s,t
q
s,s
=
5
12
∗
1
(6.11)
d
50
y
0
.
2
∗
D
0
.
6
∗
+
where:
q
s,s
=
suspended part of the sediment transport rate (m
2
/s)
q
s,t
=
total load transport rate predicted (m
2
/s)
d
50
=
mean sediment size (m)
y
=
water depth (m)
D
∗
=
dimensionless grain parameter
- In the case of lateral inflow into the system the downstream con-
centration
c
2
will change accordingly, depending upon the incoming
concentration and discharge. Continuity for the water flow and sediment
transport gives:
Q
2
=
Q
1
+
Q
i
and
c
2
Q
2
=
c
1
Q
1
+
c
i
Q
i
.
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