n_freeman2000 {HYDROCAL}

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)

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.

Value

Manning's n

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

# 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)