Direction: A rectangular channel 6.0 m wide carries a discharge of 16.0 m3 /s under uniform condition with normal depth of 1.60 m. Manning’s ‘n’ is 0.015.
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A jump is to be provided on the channel bed. The maximum height of the jump without affecting the upstream flow condition is
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- 0.50 m
- 0.40 m
- 0.30 m
- 0.20 m
Correct Option: B
Flow is sub-critical.
Specific energy, Ec
z – height
| Ec + z = y1 + | ||
| 2g |
| Ec = | × yc | |
| 2 |
| = | × |  |  | 1/3 | ||
| 2 | g |
| q = | = | = 2.67m³/s/m | ||
| b | 6 |
| Ec = | × | | | 1/3 | = 1.67 m/s | ||
| 2 | 9.81 |
| V1 = | = | = 1.67 m/s | ||
| A | 6 × 1.6 |
| ∴ 1.35 + z = 1.6 + | |
| 2 × 9.81 |
∴ z = 1.74 – 1.35 = 0.4 m.
