hydraulicCutOff2 {soilphysics}

The matric potential at the point of hydraulic cut-off using the point of maximum curvature of DE (Dexter et al. 2008) water retention curve.

Description

The pore water suction at the point of hydraulic cut-off occurs at the point where the residual water content, obtained from Dexter et al. (2008), intercepts with the Groenevelt & Grant (2004) retention curve. This function calculates the Hydraulic Cut-Off using the point of maximum curvature of the DE (Dexter et al. 2008) curve.

Usage

hydraulicCutOff2(theta_R, a1, a2, p1, p2, graph = FALSE, ...)

Arguments

theta_R

the residual water content from Dexter's (2008) water retention curve (g/g).

a1

a water content parameter from Dexter's (2008) water retention curve (g/g).

a2

a water content parameter from Dexter's (2008) water retention curve (g/g).

p1

a matric potential parameter from Dexter's (2008) water retention curve (hPa).

p2

a matric potential parameter from Dexter's (2008) water retention curve (hPa).

graph

logical; if TRUE a graphical solution with the maximum curvature point is displayed.

...

further graphical arguments. See par

Details

The arguments are the fitting parameters from Dexter's (2008) water retention curve, which can be fitted using fitsoilwater3. Further examples of how to use these parameters are given in Dexter et al. (2012).

Value

A data.frame containing the values of matric potential (hPa), pF and water content (w) at the hydraulic cut-off (hco) point.

Author(s)

Renato Paiva de Lima <[e-mail]>

References

Dexter, A.R.; Czyz, E.A.; Richard, G.; Reszkowska, A. (2008). A user-friendly water retention function that takes account of the textural and structural pore spaces in soil. Geoderma, 143:243–253.

Dexter, A.R., Czyz, E.A., Richard, G. (2012). Equilibrium, non-equilibrium and residual water: consequences for soil water retention. Geoderma, 177:63–71.

See Also

hydraulicCutOff, fitsoilwater3

Examples

# Example 1:  soils from Dexter et al. (2012), Table 4

hydraulicCutOff2(theta_R=0.1130,a1=0.0808,a2=0.0576,p1=4043.2,p2=269.1,
                  graph = TRUE, ylim=c(-0.05,0.15)) # Soil 1

hydraulicCutOff2(theta_R=0.0998,a1=0.1456,a2=0.0162,p1=3156.0,p2=71.51,
                  graph = TRUE, ylim=c(-0.20,0.30)) # Soil 4

hydraulicCutOff2(theta_R=0.0709,a1=0.0195,a2=0.1794,p1=4467.5,p2=1395.5,
                  graph = TRUE, ylim=c(-0.20,0.30)) # Soil 7

hydraulicCutOff2(theta_R=0.0359,a1=0.1014,a2=0.0459,p1=1282.4,p2=56.93,
                  graph = TRUE, ylim=c(-0.10,0.20)) # Soil 10

hydraulicCutOff2(theta_R=0.0736,a1=0.0522,a2=0.0321,p1=3516.2,p2=90.54,
                  graph = TRUE, ylim=c(-0.05,0.15)) # Soil 14

# Example 2:

# Fitting the water retention curve through the Dexter's (2008) curve
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)
if (interactive()) {
   fitsoilwater3(theta=w, x=h)
}

# Using the fitted parameter
hydraulicCutOff2(theta_R=0.1738,a1=0.07505,a2=0.316,p1=3673,p2=70.38,
                  graph = TRUE, ylim=c(-0.40,0.60))


# End (not run)