iemisc (version 0.5.0)

nc4: Krishnamurthy and Christensen method for composite Manning's n

Description

This function computes the composite Manning's n using the Krishnamurthy and Christensen method.

Usage

nc4(P, n, y)

Arguments

P

numeric vector that contains "wetted perimeter of any section i"

n

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

y

numeric vector that contains "flow depth in the ith section"

Value

• numeric vector that contains nc4 as Manning's composite n.

encoding

UTF-8

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 Krishnamurthy and Christensen method is

$$\ln n_c = \frac{\sum \limits_{i=1}^N P_iy_i^\frac{3}{2} \ln n_i}{\sum \limits_{i=1}^N P_i y_i^\frac{3}{2}}$$

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References

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

See Also

n for Manning's n for natural channels, nc1 for Horton method for composite Manning's n, nc2 for Einstein and Banks method for composite Manning's n, and nc3 for Lotter method for composite Manning's n.

Examples

library(iemisc)
nc4(n = c(0.0024, 0.035), P = c(23.65, 36.08), y = c(10.23, 7.38))