The correct answer is: B. Manning
The Manning formula is a semi-empirical formula used to calculate the mean velocity of water flow in open channels. It is named after Robert Manning, an Irish engineer who developed it in 1890. The formula is given by:
$$V = \frac{1}{n} R^{2/3} S^{1/2}$$
where:
- $V$ is the mean velocity of water flow in m/s
- $n$ is the Manning roughness coefficient
- $R$ is the hydraulic radius in m
- $S$ is the bed slope of the channel in m/m
The Manning roughness coefficient is a dimensionless number that accounts for the roughness of the channel bed and sides. It is typically determined experimentally, but it can also be estimated from tables or charts. The hydraulic radius is defined as the cross-sectional area of the channel divided by the wetted perimeter. The bed slope is the ratio of the change in elevation to the horizontal distance along the channel.
The Manning formula is widely used in hydraulic engineering applications. It is relatively simple to use and can be applied to a wide range of channels. However, it is important to note that the formula is only a semi-empirical formula, and it should not be used for critical applications.
The other options are incorrect because they are not the names of the engineers who developed the Manning formula.