nc1: Horton method for composite Manning's n

In iemisc: Irucka Embry's Miscellaneous Functions

Horton method for composite Manning's n

Description

This function computes the composite Manning's n using the Horton method.

Usage

nc1(P, n)

Arguments

P	numeric vector that contains "wetted perimeters of any section i"
n	numeric vector that contains "Manning's n of any section i"

Details

"A composite value of Manning's n for a single channel; that is, for the main channel only of a compound channel or a canal with laterally varying roughness." Source: Sturm page 118.

The equation to find Manning's composite n using the Horton method is

n_c = \left[\frac{\sum \limits_{i=1}^N P_i n_i^\frac{3}{2}}{P}\right] ^ \frac{2}{3}

n_c

Manning's composite n

P

"wetted perimeters of the entire cross section"

P_i

"wetted perimeters of any section i"

n_i

"Manning's n of any section i"

N

"total number of sections into which the wetted perimeters is divided"

Source: Sturm page 118.

Value

numeric vector that contains nc1 as Manning's composite n.

Author(s)

Irucka Embry

References

1. Terry W. Sturm, Open Channel Hydraulics, 2nd Edition, New York City, New York: The McGraw-Hill Companies, Inc., 2010, page 118.

2. Dan Moore, P.E., NRCS Water Quality and Quantity Technology Development Team, Portland Oregon, "Using Mannings Equation with Natural Streams", August 2011, https://web.archive.org/web/20210416091858/https://www.wcc.nrcs.usda.gov/ftpref/wntsc/H&H/xsec/manningsNaturally.pdf. Retrieved thanks to the Internet Archive: Wayback Machine

See Also

n for Manning's n for natural channels, nc2 for Einstein and Banks method for composite Manning's n, nc3 for Lotter method for composite Manning's n, and nc4 for Krishnamurthy and Christensen method for composite Manning's n.

Examples

library(iemisc)

# Example from the Moore Reference text
nc1(n = c(0.05, 0.035, 0.05, 0.04), P = c(22.22, 34.78, 2.00, 6.08))

iemisc documentation built on Sept. 25, 2023, 5:09 p.m.