# Kr_h: Unsaturated Hydraulic Conductivity In soilphysics: Soil Physical Analysis

## 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

 `1` ```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

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14``` ```# 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.