nc3: Lotter method for composite Manning's n

Description

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

Usage

nc3(P, n, R)

Value

numeric vector that contains nc3 as Manning's composite n.

Arguments

P: numeric vector that contains "wetted perimeter of any section i"
n: numeric vector that contains "Manning's n of any section i"
R: numeric vector that contains "hydraulic radius 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."

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

$$n_c = \frac{PR^\frac{5}{3}}{\sum \limits_{i=1}^N \frac{P_i R_i^\frac{5}{3}}{n_i}}$$

$n_c$: Manning's composite n
P: "wetted perimeter of the entire cross section"
R: "hydraulic radius of the entire cross section"
$P_i$: "wetted perimeter of any section i"
$R_i$: "hydraulic radius of any section i"
$n_i$: "Manning's n of any section i"
N: "total number of sections into which the wetted perimeter and hydraulic radius are divided"

References

Terry W. Sturm, Open Channel Hydraulics, 2nd Edition, New York City, New York: The McGraw-Hill Companies, Inc., 2010, page 118-119.

Examples

Run this code

library("iemisc")
nc3(n = c(0.0024, 0.035), P = c(23.65, 36.08), R = c(2.02, 6.23))

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