The Manning equation is used for a wide variety of uniform open channel flow calculations, including gravity flow in pipes, the topic of this course.  Gravity flow will take place in pipes for partially full flow, up to and including full pipe flow, provided that the pipe isn’t pressurized. 

Equations are presented and discussed in this course for calculating the cross-sectional area of flow, wetted perimeter, and hydraulic radius for flow of a specified depth in a pipe of known diameter.  Also included is a brief review of the Manning equation and discussion of its use to calculate a) the flow rate in a given pipe (diameter, slope, & full pipe Manning roughness) at a specified depth of flow, b) the required diameter for a specified flow rate at a target percent full in a given pipe, c) the normal depth (depth of flow) for a specified flow rate in a given pipe, d) the required pipe slope fora specified flow rate and depth of flow through a given pipe, and d) calculation of an experimentally determined value for the full pipe Manning roughness coefficient. This includes presentation and discussion of the equations for the calculations, example calculations, and screenshots of spreadsheets to facilitate the calculations.  Examples include calculation with both U.S. units and S.I. units.

Upon completion of this course, the learner will:

• Be able to calculate the cross-sectional area of flow, wetted perimeter, and hydraulic radius for less than half full flow at a given depth in a pipe of given diameter.
• Be able to calculate the cross-sectional area of flow, wetted perimeter, and hydraulic radius for more than half full flow at a given depth in a pipe of given diameter.
• Be able to use Figure 6 in the course study document to determine the flow rate at a given depth of flow in a pipe of known diameter if the full pipe flow rate is known or can be calculated.
• Be able to use Figure 6 in the course study document to determine the average water velocity at a given depth of flow in a pipe of known diameter if the full pipe average velocity is known or can be calculated.
• Be able to calculate the Manning roughness coefficient for a given depth of flow in a pipe of known diameter with known Manning roughness coefficient for full pipe flow.
• Be able to use the Manning equation to calculate the flow rate and average velocity for flow at a specified depth in a pipe of specified diameter, with known pipe slope and full pipe Manning roughness coefficient.
• Be able to calculate the normal depth for a specified flow rate of water through a pipe of known diameter, slope, and full pipe Manning roughness coefficient.
• Be able to calculate the minimum required pipe diameter for a specified flow rate of water through a pipe of known slope, full pipe Manning roughness coefficient, and target value for y/D.
• Be able to calculate the required pipe slope for a specified flow rate of water through a pipe of known diameter, slope, and full pipe Manning roughness coefficient.
• Be able to carry out the calculations in the above learning objectives using either U.S. units or S.I. units.
• Be able to use Excel spreadsheets to make partially full pipe flow calculations.