According to Kennedy, the critical velocity (V0) in metres in a channel is the mean velocity which keeps the channel free from silting or scouring. Its value is given by (where m is critical velocity ratio and D is the depth of the channel).

• A. <img src="/_files/images/civil-engineering/irrigation/15-15-32-1.png">
• B. <img src="/_files/images/civil-engineering/irrigation/15-15-32-2.png">
• C. <img src="/_files/images/civil-engineering/irrigation/15-15-32-3.png">
• D. <img src="/_files/images/civil-engineering/irrigation/15-15-32-4.png">