According to Kennedy, the critical velocity (V0) in meters 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. V0 = 0.84 mD0.64 B. V0 = 0.55 mD0.64 C. V0 = 0.84 mD0.54 D. V0 = 0.55 mD0.54

The correct answer is: A. V0 = 0.84 mD0.64

The critical velocity is the minimum velocity required to keep a channel free from silting or scouring. It is a function of the channel’s depth, slope, and sediment characteristics. The Kennedy equation is a widely used empirical equation for estimating the critical velocity. It is given by:

$$V_c = 0.84 \times m \times D^{0.64}$$

where:

• $V_c$ is the critical velocity in meters per second
• $m$ is the critical velocity ratio, which is a dimensionless number that depends on the channel’s sediment characteristics
• $D$ is the depth of the channel in meters

The Kennedy equation is based on experimental data for a wide range of channels. It has been shown to be accurate for a variety of sediment types and channel geometries.

Option B is incorrect because it uses a value of $m$ that is too low. The value of $m$ should be between 0.8 and 1.0 for most channels.

Option C is incorrect because it uses a value of $m$ that is too high. The value of $m$ should be between 0.8 and 1.0 for most channels.

Option D is incorrect because it uses the wrong power of $D$. The correct power of $D$ is 0.64.