n_freeman2000: Compute hydraulic roughness due to vegetation following Freeman, Rahymeyer, and Copeland (2000)

Description

n_freeman2000 calculate Manning's n using the Freeman, Rahymeyer, and Copeland (2000) method for estimating vegetative roughness

Usage

n_freeman2000(depth, slope, area, hp, hlm, We, Ds, pnum, snum, restrict = TRUE)

Value

Manning's n

Arguments

depth: flow depth (H) in meters. Assumes wide channel geometry where depth is approximately equal to hydraulic radius.
slope: channel bed slope (S)
area: sample vegetative plot bed area in square meters, a list of index 5
hp: average plant height (h_p) in meters, a list of index 5
hlm: average leaf mass height (hlm) in meters, a list of index 5
We: average leaf mass width (We) in meters, a list of index 5
Ds: average stem diameter (Ds) in meters, a list of index 5
pnum: number of plants in the corresponding indices, a list of index 5
snum: number of stems at H/4 in the corresponding indices, a list of index 5
restrict: allows for function parameters to restrict certain values. Type bool. Default TRUE.

References

Freeman, G. E., W. H. Rahmeyer, and R. R. Copeland. 2000. Determination of Resistance Due to Shrubs and Woody Vegetation. ERDC/CHL TR-00-25. U.S. Army Engineer Research and Development Center, Vicksburg, Mississippi.

Examples

Run this code

# Result: Manning's n of 0.013
depth <- 6
slope <- 0.005
area <- 100
hp <- c(0.51,0.71,0.2,0.97,0.71)
hlm <- c(0.45,0.71,0.16,0.9,0.62)
We <- c(0.229,0.356,0.254,0.482,0.178)
Ds <- c(0.0095,0.0095,0.0063,0.0252,0.0063)
pnum <- c(2,2,2,1,3)
snum <- c(1,1,2,2,6)
n_freeman2000(depth,slope,area,hp,hlm,We,Ds,pnum,snum)

# Result: Manning's n of 0.0183
depth <- 0.3
slope <- 0.005
area <- 100
hp <- c(0.51,0.71,0.2,0.97,0.71)
hlm <- c(0.45,0.71,0.16,0.9,0.62)
We <- c(0.229,0.356,0.254,0.482,0.178)
Ds <- c(0.0095,0.0095,0.0063,0.0252,0.0063)
pnum <- c(2,2,2,1,3)
snum <- c(1,1,2,2,6)
n_freeman2000(depth,slope,area,hp,hlm,We,Ds,pnum,snum)

# Result: Vegetation height must be positive.
depth <- 0.3
slope <- 0.005
area <- 100
hp <- c(0.51,0.71,0.2,0.97,-0.23)
hlm <- c(0.45,0.71,0.16,0.9,0.62)
We <- c(0.229,0.356,0.254,0.482,0.178)
Ds <- c(0.0095,0.0095,0.0063,0.0252,0.0063)
pnum <- c(2,2,2,1,3)
snum <- c(1,1,2,2,6)
n_freeman2000(depth,slope,area,hp,hlm,We,Ds,pnum,snum)

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