Kr_h: Unsaturated Hydraulic Conductivity

Description Usage Arguments Value Author(s) References Examples

View source: R/Kr_h.R

Description

A closed-form analytical expressions for calculating the relative unsaturated hydraulic conductivity as a function of soil water tension (h) based on van Genuchten's water retention curve.

Usage

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Kr_h(Ks, alpha, n, h, f=0.5)

Arguments

Ks

Saturated hydraulic conductivity (e.g. cm/day).

alpha

The scale parameter of the van Genuchten's model (hPa^-1).

n

The shape parameter in van Genuchten's formula.

h

The water tension (hPa).

f

The pore-connectivity parameter. Default 0.5 [Mualem, 1976].

Value

numeric, the value of unsaturated hydraulic conductivity.

Author(s)

Renato Paiva de Lima <renato_agro_@hotmail.com>

References

Guarracino, L. (2007). Estimation of saturated hydraulic conductivity Ks from the van Genuchten shape parameter alpha. Water Resources Research, 43(11).

Van Genuchten, M. T. (1980). A closed-form equation for predicting the hydraulic conductivity of unsaturated soils 1. Soil Science Society of America Journal 44(5):892-898.

Examples

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# EXAMPLE 1
Kr_h(Ks = 1.06*10^2, alpha = 0.048, n = 1.5,h=100, f=0.5)

# EXAMPLE 2
x <- seq(log10(1), log10(1000),len=100)
h <- 10^x
y <- Kr_h(Ks = 1.06*10^2, alpha = 0.048, n = 1.5,h=h, f=0.5)
plot(x=h,y=y, log="yx", xlab="h (hPa)", yaxt='n',
    ylab="", ylim=c(0.001,100), xlim=c(1,10000))
mtext(expression(K[r] ~ (cm~d^-1)), 2, line=2)
ax <- c(0.001, 0.01, 0.1, 1, 10, 100)
axis(2,at=ax, labels=ax)

# End (not run)

soilphysics documentation built on Jan. 13, 2021, 7:06 p.m.