nc2 {iemisc} | R Documentation |
Einstein and Banks method for composite Manning's n
Description
This function computes the composite Manning's n using the Einstein and Banks method.
Usage
nc2(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 Einstein and Banks method is
n_c = \left[\frac{\sum \limits_{i=1}^N P_i n_i^2}{P}\right] ^ \frac{1}{2}
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 nc2 as Manning's composite n.
Author(s)
Irucka Embry
References
Terry W. Sturm, Open Channel Hydraulics, 2nd Edition, New York City, New York: The McGraw-Hill Companies, Inc., 2010, page 118-119.
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, nc1
for
Horton 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
nc2(n = c(0.05, 0.035, 0.05, 0.04), P = c(22.22, 34.78, 2.00, 6.08))