haverkamp: R optmisation of a two-parameter van Genuchten particle size...

In gowusu/vadose: The estimation of saturated hydraulic conductivity and soil water retention Curves in the vadose zone

Description

The function optimises 2-parameter van Genuchten particle size distribution function of Haverkamp & Parlange (1986).

Usage

haverkamp(data = NULL, D = NULL, fr = NULL, a = 1, b = 1, p = NULL,
  group = NULL)

## Default S3 method:
haverkamp(data = NULL, D = NULL, fr = NULL, a = 1,
  b = 1, p = NULL, group = NULL)

## S3 method for class 'haverkamp'
plot(x, main = "Particle Size Distribution Function",
  xlab = "Particle Diameter", ylab = "Fraction", ...)

## S3 method for class 'haverkamp'
coef(object, ...)

## S3 method for class 'haverkamp'
predict(object, D, ...)

Arguments

data	a dataframe of Particle Size Distribution. It can have column names of diameter of the particles "D" [mm], and fraction of the particles "fr" that ranges from 0-1.
D	character. The corresponding diameter in the data.
fr	character. The corresponding fraction of the particles.
a	an initial value of 'a' parameter to be optimised
b	an initial value of 'b' parameter to be optimised
p	porosity[g/m^3]
group	character. The name of the group variables if the data is from different areas.
x	a return object of the function.
main	Title of the plot
xlab	x label of the plot
ylab	y label of the plot
...	Any other graphical parameter
object	Model output object

Value

• PD: predicted fraction by mass of particles passing a particular diameter

• sand: percentage of sand

• clay: percentage of clay

• silt: percentage of silt

• a: optimised a parameter

• b: optimised b parameter

Author(s)

George Owusu

References

Haverkamp, R., & Parlange, J. Y. (1986). Predicting the Water-Retention Curve from Particle-Size Distribution:1. Sandy Soils Without Organic Matter. Soil Sc, 142, 325-339.

See Also

zhuang3, zhuang4,lass3,logarithmic, logistic2, logistic3,logistic4,fredlund3, fredlund4, jaky,andersson,gompertz

Other van-Genuchten functions: zhuang3, zhuang4

Examples

data=read.csv(system.file("ext","sys","soil2.csv",package="vadose"))
single<- subset(data, ID=="30B20_1")
mod=haverkamp (data=single,p="sand",D="D",fr="Sand.")
plot(mod)
## Not run: 
#group simulation
mod2=haverkamp (data=data,D="D",fr="FractionSand",group="ID")
mod2$coef

## End(Not run)

gowusu/vadose documentation built on May 17, 2019, 7:59 a.m.