Question

Which of the followings is the safe permissible velocity of water flowing in a channel?

• A. 15 cm/sec
• B. <15 cm/sec
• C. 30 cm/sec
• D. >30 cm/sec

Hint:

Permissible velocity depends on soil type.
- Clay: 1.2-1.8 m/s
- Sandy loam: 0.6-0.8 m/s
- Fine sand: 0.3-0.4 m/s
Channel lining increases permissible velocity.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Safe permissible velocity is the maximum velocity that does not cause erosion or scouring of the channel bed and banks.

Step 2: Detailed Explanation:
For a channel to be stable, the velocity should be less than the critical velocity for erosion.
Safe permissible velocity depends on the type of soil:
- Clay: 1.2-1.8 m/s
- Sandy loam: 0.6-0.8 m/s
- Coarse sand: 0.5-0.6 m/s
- Fine sand: 0.3-0.4 m/s
For most agricultural channels, safe velocity is < 15 cm/sec for fine-textured soils.
Option A (15 cm/sec) is too low and not practical.
Option C (30 cm/sec) is higher than safe for many soils.
Option D (>30 cm/sec) would cause erosion.
Thus, the safe permissible velocity is <15 cm/sec for most soils.

Step 3: Final Answer:
Thus, the safe permissible velocity of water flowing in a channel is <15 cm/sec.
[0.5cm]