Time of concentration by the Kerby method (overland flow)

The Kerby formula for overland (sheet) flow time of concentration, suited to the upstream portion of a catchment before channel flow begins. Often combined with Kirpich channel time in the Kerby-Kirpich approach.

Usage

tc_kerby(length_m, slope, retardance = 0.4)

Arguments

length_m

Overland flow length in metres.

slope

Overland slope (dimensionless).

retardance

Kerby retardance roughness coefficient (dimensionless); higher for rougher surfaces. Default 0.4 (average grass).

Value

Overland time of concentration in minutes.

References

Kerby, W. S. (1959) Time of concentration for overland flow. Civil Engineering, 29(3), 174.

Examples

tc_kerby(100, 0.01, retardance = 0.4)
#> [1] 23.79713