| Kr_h {soilphysics} | R Documentation |
Unsaturated Hydraulic Conductivity
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
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
# 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)