SSphilip {HydroMe}R Documentation

A selfstarting function for estimating infiltration parameters in the Philips model

Description

This selfstarting function estimates the infiltration parameters contained in the Philips model. It has an initial attribute that creates initial estimates of the parameters fc, and S

Usage

SSphilip(input, fc, S)

Arguments

input A numeric vector of Time
fc A numeric parameter representing the final steady infiltration capacity
S a numeric parameter representing the slope of the infiltration characteristic curve at the early tmies of the infiltration process. It is the estimate of sorptivity at the supply moisture content

Value

a numeric vector of the same length as input. It is the value of the expression fc+(0.5*S)/sqrt(input) . It represents the fitted values by the Philips model

Author(s)

Omuto, Christian Thine

References

Philip, J.R., 1957 The theory of infiltration 4: Sorptivity and algebraic infiltration equations Soil Science 84, 257-264

See Also

SShort, SSGampt

Examples

##-- Use infiltration data 
data(infiltration)
 philip.nls <-nls(Rate~SSphilip(Time, fc, S), data=infiltration) 
plot(fitted(philip.nls)~infiltration$Rate) # Plot the fitted versus measured


[Package HydroMe version 1.0 Index]