Geoscience Reference
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1.8
Ks/Du=18.75E-6
Ks/Du=10.50E-6
Ks/Du=8.73E-6
R 2 = 0.86
1.6
1.4
1.2
R 2 = 0.77
1
0.8
R 2 = 0.57
0.6
0.4
0.2
0
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Fr
Fig. 7 The effect of Froude number of the upstream on the entering sediment ratio
0.3
a
d
0.25
0.2
Fr=0.25
Fr=0.30
Fr=0.35
Fr=0.40
Fr=0.45
0.15
1
0.1
m=1.5
T
0.05
B
T1
0
c
b
0
0.1
0.2
0.3
0.4
0.5
0.6
T1(cm)
Fig. 8 The dividing stream surface (DSS) for different Froude numbers
increase. The results for the two depths, 20 and 25 cm, are similar, but the value of
G r / Q r with a 10-cm depth shows a difference, the reason of which can be discerned
in Fig. 8 . This figure also shows the Dividing Stream Surface (DSS) for three
depths: 10, 20, and 25 cm. It is seen that the stream tube dimensions in 20- and
25-cm depths are close to each other, and less than for 10 cm, owing to the fact that
the diversion flow ratios at 20 and 25 cm are almost the same, but at a depth of
10 cm it is high (Table 1 ). At this depth ( k s / D u ΒΌ
18.75E-6), the transverse velocity
distribution is such that G r decreases too, making a considerable disparity between
the value of G r / Q r ratio at the 10 cm and that for the other two depths.
According to Fig. 8 , it is recommended that in the irrigation channels, after the
determination of the diversion flow using the gates regulating the water surface, the
depth of water should be so adjusted that the approaching Froude number falls into
the interval 0.35-0.40, supplying a minimum G r / Q r .
 
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