soilphysics (version 2.1)

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

Description

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)