Kappa3Est: Kappa3 distribution estimates from parameters

In UKFE: UK Flood Estimation

Kappa3 distribution estimates from parameters

Description

Estimated quantiles as function of return period (RP) and vice versa, from user input parameters

Usage

Kappa3Est(loc, scale, shape, q = NULL, RP = 100)

Arguments

loc	location parameter
scale	scale parameter
shape	shape parameter
q	quantile. magnitude of the variable under consideration
RP	return period

Details

If the argument q is used, it overrides RP and provides RP as a function of q (magnitude of variable) as opposed to q as a function of RP. This is the Kappa3 distribution as defined in Kjeldsen, T (2019), 'The 3-parameter Kappa distribution as an alternative for use with FEH pooling groups.' (Circulation - The Newsletter of the British Hydrological Society, no. 142).

This function applies a probability distribution model which assumes that the sample data is independent and identical, i.e. the assumption is that all observations in the sample would not impact or depend on any other. Furthermore, all observations are from the same underlying process which has not changed over the period of record (stationarity).

Value

quantile as a function of RP or vice versa

Author(s)

Anthony Hammond

Examples

# Get an annual maximum sample, estimate the parameters, and the 50-year RP flow
am_27090 <- GetAM(27090)

# Get the parameters and store in an object
pars <- as.numeric(Kappa3Pars(am_27090$Flow))

# Get an estimate of the 50-year flow
Kappa3Est(pars[1], pars[2], pars[3], RP = 50)

# Estimate the RP for a 600 m^3/s discharge
Kappa3Est(pars[1], pars[2], pars[3], q = 600)

UKFE documentation built on Nov. 5, 2025, 6:25 p.m.