soilphysics (version 1.2)

fitsoilwater: Interactive Estimation of van Genuchten's (1980) Model Parameters

Description

This function consists in an interactive graphical adjustment of the soil water retention curve via van Genuchten's (1980) formula. The nonlinear least-squares estimates can be achieved taking the graphical initial values.

Usage

fitsoilwater(theta, x, xlab = NULL, ylab = NULL, ...)

Arguments

theta

a numeric vector containing the values of soil water content.

x

a numeric vector containing the matric potential values.

xlab

a label for the x axis; if is NULL, the label "Matric potential" is used.

ylab

a label for the y axis; if is NULL, the label "Soil water content" is used.

...

further graphical arguments; see par.

Value

• A plot of theta versus x and the curve of the current fitted model according to the adjusted parameters in an external interactive panel. Pressing the button "NLS estimates" a nls summary of the fitted model is printed on console whether convergence is achieved, otherwise a warning box of "No convergence" is shown.

References

Genuchten, M. T. van. (1980). A closed form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, 44:892-898.

See Also

nls, soilwater

Examples

# Liu et al. (2011)
h <- c(0.001, 50.65, 293.77, 790.14, 992.74, 5065, 10130, 15195)
w <- c(0.5650, 0.4013, 0.2502, 0.2324, 0.2307, 0.1926, 0.1812, 0.1730)
fitsoilwater(w, h)

# End (not run)