The design values of hydraulic parameters of selected channels were taken from the longitudinal sections of the channels provided by the PISIP office. For post-lining data, actual measurements of the hydraulic parameters were made in the field. A channel's cross-section is most economical or most efficient when it passes a maximum discharge for a given cross-section area, resistance coefficient, and bottom slope. The cross-sectional area has a direct relationship with construction cost. Therefore, an optimum cross-section area needs to be designed keeping in view all other factors. The comparison of design and measured values of the cross-sectional areas conclude that the under-design values of the channel cross-sectional area ranged from 0.51 to 15% while the over-design values ranged from 0.46 to 10%. The overall average of the over-designed cross-sectional area was 5% and under-designed was 7%. This analysis suggests that the variation in design and measured values of the cross-section is reasonably close. The over-design variation in the wetted perimeter ranged from 3 to 33% with an overall average of 15% and average under-design values ranged from 3 to 19% with an overall average of 11%. The comparison of design and measured values of wetted perimeter suggests that under-design values ranged from 3 to 19% and over-design values ranged from 2.50 to 19% with an average of 11%. These results are tabulated in Table 5 and their statistics are depicted in Figures 7 and 8. The overall summary of physically measured hydraulic parameters is shown in Figure 9, which indicates that 51% of sites are overdesigned, 46 are under-designed, while only 3% are as per design. The greatest variations have been observed in the water surface slope in the channels and the least variation in the wetted perimeter as shown in Figure 10.
Table 5

Comparison of design and measured hydraulic parameters (1 cfs = 0.0283 cumecs. 1 ft2 = 0.093 m2. 1 ft = 0.3048 m. 1 ft/s = 0.3048 m/s)

Name of channelLocation RD (ft)Discharge (cfs) Q
X-sectional (ft2) A
Wetted perimeter (ft) P
Velocity (ft/s) V
Water surface slope S
Manning's n (Design n = 0.016)
Designmeasured% variationDesignmeasured% variationDesignmeasured% variationDesignmeasured% variationDesignmeasured% variationDesignmeasured% variationMeasured% variation
Nasrana Disty 129 + 140 43 44.7 21.2 19.77 −7 12.7 13.7 2.26 11 1.7 1.44 −14 0.3 0.35 40 0.011 30
145 + 700 30 34.6 16 15.7 15.71 10.9 11.42 1.9 2.2 16 1.6 1.32 −15 0.3 0.35 40 0.011 34
156 + 160 29 18.2 −38 16.6 12.1 −27 9.95 10.81 1.8 1.5 −15 1.3 1.1 −17 0.3 0.32 0.009 44
173 + 560 10 9.4 −7 5.7 −5 6.89 6.63 −4 1.5 1.65 10 0.8 0.7 −10 0.3 0.32 0.007 59
Sehti Wala Minor 0 + 350 14 15.5 13 8.4 9.6 14 9.1 14 1.6 1.5 −6 1.1 1.09 0.3 0.45 61 0.011 34
20 + 230 7.1 6.1 −14 4.5 −10 6.1 5.74 −6 1.5 1.55 0.8 0.72 −12 0.3 0.5 67 0.008 48
Lagar Disty 1 + 100 35 39.2 13 20 22.9 15 12.5 14.61 17 1.8 1.71 −3 1.6 1.56 −1 0.2 0.18 −10 0.009 47
24 + 100 28 30 17 19.2 13 11 13 18 1.7 1.56 −8 1.5 1.49 0.2 0.5 127 0.014 14
29 + 250 17 18.1 11 13.4 22 9.25 10.75 16 1.5 1.35 −10 1.2 1.27 0.2 0.5 127 0.012 23
59 + 100 9.9 7.4 −25 5.6 −20 7.49 7.67 1.5 1.32 −12 0.9 0.82 −13 0.2 0.5 127 0.009 43
Khikhy Disty 97 + 990 44 41.9 −3 20 20.9 12.6 14.89 18 2.01 −1 1.6 1.42 −12 0.4 0.3 −25 0.01 36
121 + 300 9.1 5.1 −43 3.9 −22 6.33 5.35 −16 1.8 1.75 −1 0.8 0.71 −12 0.4 0.3 −25 0.007 59
Sillanwali Disty 1 + 400 11 12.2 7.9 −1 7.77 7.75 1.5 1.54 1.01 −1 0.3 0.4 60 0.01 41
14 + 850 1.5 1.3 −10 1.44 1.2 −18 3.26 2.8 −14 1.5 1.1 −27 0.4 0.4 −9 0.4 0.5 25 0.006 64
Khadir Disty 231 + 600 47 31.4 −33 26 19.6 −25 14.8 14.07 −5 1.8 1.6 −9 1.7 1.42 −18 0.4 0.5 43 0.013 17
260 + 100 15 15.5 10 11.5 15 15.3 12.33 −20 1.6 1.35 −13 1.2 1.26 0.4 0.5 43 0.012 23
Arain Minor − 1 21 + 900 40 39.8 −2 22.5 19.5 −13 13.1 13.49 1.8 1.9 1.4 1.42 0.2 0.19 0.008 49
50 + 500 13 13 8.49 7.5 −12 7.93 7.66 −3 1.5 1.6 1.1 0.95 −11 0.3 0.35 40 0.009 47
IR/3R Hakra 22 + 600 53 45.9 −14 32 19.82 −38 16 15.09 −6 2.3 2.26 1.31 −35 0.3 0.5 100 0.013 21
46 + 250 14 8.6 −40 16 5.7 −64 7.6 −16 1.8 1.49 −15 1.8 0.75 −58 0.3 0.4 60 0.008 51
Min    −43   −64   −20   −27   −58   −25  14
Max    16   22   18   16     127  64
Avg    −8   −9     −3   −11   45  39
Name of channelLocation RD (ft)Discharge (cfs) Q
X-sectional (ft2) A
Wetted perimeter (ft) P
Velocity (ft/s) V
Water surface slope S
Manning's n (Design n = 0.016)
Designmeasured% variationDesignmeasured% variationDesignmeasured% variationDesignmeasured% variationDesignmeasured% variationDesignmeasured% variationMeasured% variation
Nasrana Disty 129 + 140 43 44.7 21.2 19.77 −7 12.7 13.7 2.26 11 1.7 1.44 −14 0.3 0.35 40 0.011 30
145 + 700 30 34.6 16 15.7 15.71 10.9 11.42 1.9 2.2 16 1.6 1.32 −15 0.3 0.35 40 0.011 34
156 + 160 29 18.2 −38 16.6 12.1 −27 9.95 10.81 1.8 1.5 −15 1.3 1.1 −17 0.3 0.32 0.009 44
173 + 560 10 9.4 −7 5.7 −5 6.89 6.63 −4 1.5 1.65 10 0.8 0.7 −10 0.3 0.32 0.007 59
Sehti Wala Minor 0 + 350 14 15.5 13 8.4 9.6 14 9.1 14 1.6 1.5 −6 1.1 1.09 0.3 0.45 61 0.011 34
20 + 230 7.1 6.1 −14 4.5 −10 6.1 5.74 −6 1.5 1.55 0.8 0.72 −12 0.3 0.5 67 0.008 48
Lagar Disty 1 + 100 35 39.2 13 20 22.9 15 12.5 14.61 17 1.8 1.71 −3 1.6 1.56 −1 0.2 0.18 −10 0.009 47
24 + 100 28 30 17 19.2 13 11 13 18 1.7 1.56 −8 1.5 1.49 0.2 0.5 127 0.014 14
29 + 250 17 18.1 11 13.4 22 9.25 10.75 16 1.5 1.35 −10 1.2 1.27 0.2 0.5 127 0.012 23
59 + 100 9.9 7.4 −25 5.6 −20 7.49 7.67 1.5 1.32 −12 0.9 0.82 −13 0.2 0.5 127 0.009 43
Khikhy Disty 97 + 990 44 41.9 −3 20 20.9 12.6 14.89 18 2.01 −1 1.6 1.42 −12 0.4 0.3 −25 0.01 36
121 + 300 9.1 5.1 −43 3.9 −22 6.33 5.35 −16 1.8 1.75 −1 0.8 0.71 −12 0.4 0.3 −25 0.007 59
Sillanwali Disty 1 + 400 11 12.2 7.9 −1 7.77 7.75 1.5 1.54 1.01 −1 0.3 0.4 60 0.01 41
14 + 850 1.5 1.3 −10 1.44 1.2 −18 3.26 2.8 −14 1.5 1.1 −27 0.4 0.4 −9 0.4 0.5 25 0.006 64
Khadir Disty 231 + 600 47 31.4 −33 26 19.6 −25 14.8 14.07 −5 1.8 1.6 −9 1.7 1.42 −18 0.4 0.5 43 0.013 17
260 + 100 15 15.5 10 11.5 15 15.3 12.33 −20 1.6 1.35 −13 1.2 1.26 0.4 0.5 43 0.012 23
Arain Minor − 1 21 + 900 40 39.8 −2 22.5 19.5 −13 13.1 13.49 1.8 1.9 1.4 1.42 0.2 0.19 0.008 49
50 + 500 13 13 8.49 7.5 −12 7.93 7.66 −3 1.5 1.6 1.1 0.95 −11 0.3 0.35 40 0.009 47
IR/3R Hakra 22 + 600 53 45.9 −14 32 19.82 −38 16 15.09 −6 2.3 2.26 1.31 −35 0.3 0.5 100 0.013 21
46 + 250 14 8.6 −40 16 5.7 −64 7.6 −16 1.8 1.49 −15 1.8 0.75 −58 0.3 0.4 60 0.008 51
Min    −43   −64   −20   −27   −58   −25  14
Max    16   22   18   16     127  64
Avg    −8   −9     −3   −11   45  39
Figure 7

Percentage variation of hydraulic parameters from design values.

Figure 7

Percentage variation of hydraulic parameters from design values.

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Figure 8

Number of channel sections found overdesigned, under designed, and as per design with respect to different hydraulic parameters (i.e., Q, A, P, V, R, S, n) (1 cfs = 0.0283 cumecs. 1 ft2 = 0.093 m2. 1 ft = 0.3048 m. 1 ft/s = 0.3048 m/s).

Figure 8

Number of channel sections found overdesigned, under designed, and as per design with respect to different hydraulic parameters (i.e., Q, A, P, V, R, S, n) (1 cfs = 0.0283 cumecs. 1 ft2 = 0.093 m2. 1 ft = 0.3048 m. 1 ft/s = 0.3048 m/s).

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Figure 9

Summary of channel sections from the point-of-view of as per design, under-designed, and over-designed.

Figure 9

Summary of channel sections from the point-of-view of as per design, under-designed, and over-designed.

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Figure 10

Range of variation of hydraulic parameters from the design values.

Figure 10

Range of variation of hydraulic parameters from the design values.

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