nc4 | R Documentation |
This function computes the composite Manning's n using the Krishnamurthy and Christensen method.
nc4(P, n, y)
P |
numeric vector that contains "wetted perimeters 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" |
"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}}
n_c
Manning's composite n
P_i
"wetted perimeters of any section i"
y_i
"flow depth in the ith section"
n_i
"Manning's n of any section i"
"total number of sections into which the wetted perimeters and hydraulic radius are divided"
numeric vector that contains nc4 as Manning's composite n.
Irucka Embry
Terry W. Sturm, Open Channel Hydraulics, 2nd Edition, New York City, New York: The McGraw-Hill Companies, Inc., 2010, page 118-119.
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.
library(iemisc)
nc4(n = c(0.0024, 0.035), P = c(23.65, 36.08), y = c(10.23, 7.38))
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