Table 4.11. Bed Material Discharge Calculations for Sample Problem by Applying the Colby
(Individual Size Fraction).
102ib
D
y
W
V
qn
k1
1
2
3
4
5
6
7
0.495
17.8
1.36
103
2.93
12
0.92
1.76
136
4.44
40
0.91
2.50
170
6.63
112
0.91
3.30
194
8.38
193
0.90
4.14
234
9.92
265
0.90
0.351
40.2
1.36
103
2.93
15
0.92
1.76
136
4.44
45
0.91
2.50
170
6.63
120
0.91
3.30
194
8.38
210
0.90
4.14
234
9.92
290
0.90
0.248
32.0
1.36
103
2.93
18
0.92
1.76
136
4.44
53
0.91
2.50
170
6.63
140
0.91
3.3
194
8.38
240
0.90
4.14
234
9.92
345
0.90
0.175
5.8
1.36
103
2.93
23
0.92
1.76
136
4.44
64
0.91
2.50
170
6.63
163
0.91
3.30
194
8.38
305
0.90
4.14
234
9.92
420
0.90
k2
k3
qT
IbqT
IbQT
ibQT
8
9
10
11
12
13
1.20
0.62
13
2.3
237
1,710
1.21
0.62
43
7.7
1,050
6,908
1.22
0.62
119
21.0
3,570
22,780
1.23
0.62
205
37.0
7,180
45,560
1.25
0.62
288
51.0
11,900
77,640
1.20
0.92
16
6.4
659
1.21
0.92
49
20.0
2,720
1.22
0.92
132
53.0
9,010
1.23
0.92
230
93.0
18,000
1.25
0.92
323
130.0
30,420
1.20
1.00
20
6.4
659
1.21
1.00
58
19.0
2,580
1.22
1.00
155
50.0
8,500
1.23
1.00
266
85.0
16,500
1.25
1.00
388
124.0
29,000
1.20
0.97
25
1.5
155
1.21
0.97
70
4.1
558
1.22
0.97
180
10.0
1,700
1.23
0.97
337
20.0
3,880
1.25
0.97
471
27.0
6,320
Notes:
(1)
D, mm (representative grain size; given in Table 4.7
ib (fraction of bed material), taken from Table 4.7
(2)
(3)
y, ft, (average flow depth), taken from Table 4.8, Column 13
(4)
W, ft, (top width), taken from Table 4.8, Column 16
(5)
V, fps (average velocity), taken from Table 4.8, Column 7
qn, tons/day-ft (incorrect sediment discharge per unit width by assuming the bed is composed entirely of one sand of size
(6)
D) taken from Figure 4.13 by interpolation on logarithmic paper for the given V, D, and y
(7) k1 = f (y,T) (correction factor for temperature), given in Figure 4.14
(8) k2 = f (y,Cf) (correction factor for fine sediment concentration), given in Figure 4.14
(9) k3 = f (D50) (correction factor for sediment size), given in Figure 4.14
(10) qT = [1 + (k1K2 -1) k3]qn, tons/day-ft (corrected bed material discharge per unit width by assuming the bed is
composed entirely of one sand of size D)
(11) ibqt, tons/day-ft, (bed material discharge per unit width for a size fraction for entire cross section)
(12) ibQt = WibqT, tons/day, (bed material discharge for a size fraction for entire cross section)
(13) ibQT, tons/day, (bed material discharge for all size fractions for entire cross section)
4.51
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