n_brownlie1981 {HYDROCAL}

Compute form roughness via Brownlie (1981)

Description

n_brownlie1981 calculate Manning's n using the Brownlie (1981) Method for estimating form roughness.

Usage

n_brownlie1981(depth, slope, d16, d50, d84, restrict = TRUE)

Arguments

depth

flow depth (H) in meters (m). The original model was calibrated for 0.025 m < H < 17 m.

slope

channel slope (S) in (m/m). The original model was calibrated for 3*10^-6 < S < 0.037.

d16

grain size (d16) in millimeters.

d50

grain size (d50) in millimeters. The original model was calibrated for 0.088 mm < d50 < 2.8 mm.

d84

grain size (d84) in millimeters.

restrict

allows for function parameters to restrict certain values. Type bool. Default TRUE.

Value

Manning's n

References

Brownlie, W. R. 1981. Prediction of flow depth and sediment discharge in open channels. Report No. KH-R-43A. W.M. Keck Laboratory of Hydraulics and Water Resources. California Institute of Technology.

Examples

# Result: Manning's n of 0.022
n_brownlie1981(10,0.02,1,1.1,1.2)

# Result: Manning's n of 0.018
n_brownlie1981(2.5,0.01,0.1,0.2,0.5)

# Result: Manning's n of 0.045
n_brownlie1981(15,0.003,0.6,0.9,1)

# Result: Depth must be within 0.025 and 17 m.
n_brownlie1981(20,0.003,0.6,0.9,1)