## 7.3 Manning's Equation

Manning's formula, published in 1890, gives the value of c in the Chezy formula as

The complete Manning formula being

and combining with the Chezy equation

 where A = cross-sectional area of flow in square feet S = slope, or grade, in ft/ft R = hydraulic radius, feet n = coefficient of roughness

In many computations, it is convenient to group the properties peculiar to the cross section in one term called conveyance (K)or

Then

Uniform flow of clean water in a straight, unobstructed channel would be a simple problem but is rarely attained. Manning's formula gives reliable results if the channel cross section, roughness, and slope are fairly constant over a sufficient distance to establish uniform flow.

This subsection courtesy of American Iron and Steel Institute.

Figure 7.36: Nomograph for solution of Manning's equation. ( Courtesy American Iron and Steel Institute.)

Figure 7.37: Nomograph for headwater depth of box culverts with entrance control. ( Courtesy American Iron and Steel Institute.)
 1. Fairly regular section: a. Some grass and weeds, little or no brush 0.030 0.035 b. Dense growth of weeds, depth of flow materially greater than weed height. 0.035 0.05 c. Some weeds, light brush on banks 0.035 0.05 d. Some weeds, heavy brush on banks 0.05 0.07 e. Some weeds, dense willows on banks 0.06 0.08 f. For trees within channel, with branches...

##### Products & Services
Honing, Lapping, and Super-finishing Machines
Honing, lapping and super-finishing equipment improve surface finish or geometry to tight tolerances.
Agricultural and Farming Products and Equipment

Agricultural farming products and equipment concerns the vast array machinery, tools, and vehicles employed in horticultural and animal husbandry industries.

Flow Switches
Flow switches are devices that monitor flow and send a trip signal to other devices, like a pump, for protection. These switches can be used for the measurement of gases, liquids, and steam.
Backflow Preventers
Backflow preventers are assemblies consisting of two check valves and two shut off valves. These assemblies may also include test cocks for each chamber.
Ion Specific Electrode Meters
Ion specific electrode meters are millivolt meters that interface with ion selective electrodes (ISEs). These meters take the potential generated by the electrode and convert it into units of concentration.

##### Topics of Interest

7.4 Channel Protection If the mean velocity exceeds that permissible for the particular kind of soil, the channel should be protected from erosion. Grass linings are valuable where grass can be...

PROBLEM 1.1 Water flows by gravity at a rate of 500 gallons per minute through 5 miles of cast iron pipe from one reservoir to another reservoir located 200 feet below. Calculate the minimum pipe...

Kenneth J. Williamson Wastewater Flows Wastewater flows are comprised of domestic and industrial wastewaters, infiltration, inflow, and storm water. Most modern sanitary sewers are separated from...

Kenneth J. Williamson WASTEWATER FLOWS Wastewater flows are comprised of domestic and industrial wastewaters, infiltration, inflow, and storm water. Most modern sanitary sewers are separated from...

Dr. Bruce E. Larock This chapter will review the two equations that are likely to be found in the FE examination. A more thorough presentation may be found in the Civil Engineering License Review or...

Product Announcements
Lapmaster-Wolters International
Lapmaster-Wolters International
Lapmaster-Wolters International