Which formula determines the velocity of uniform flow in sloping drains?

The correct choice is the Manning Formula, which is specifically designed to calculate the velocity of uniform flow in open channels, including sloping drains. This formula takes into consideration the channel's cross-sectional shape, slope, and roughness, providing a way to estimate the flow velocity based on these parameters.

The Manning Formula is expressed as:

[ v = \frac{1}{n} R^{2/3} S^{1/2} ]

Where ( v ) is the velocity, ( n ) is the Manning's roughness coefficient, ( R ) is the hydraulic radius, and ( S ) is the slope of the energy line. This formula effectively captures the influence of the terrain and material characteristics of the channel on flow behavior, making it particularly suitable for assessing uniform flow conditions.

Understanding the Manning Formula is crucial for plumbing design, especially in applications involving stormwater management, wastewater systems, and other drainage situations where uniform flow is achieved in a gravity-driven system. Its widespread use in civil and environmental engineering enhances both the reliability and efficiency of hydraulic calculations in these contexts.