KSSL_VG_model: Develop a Water Retention Curve from KSSL Data

Description Usage Arguments Details Value Note Author(s) References Examples

View source: R/KSSL_VG_model.R

Description

Water retention curve modeling via van Genuchten model and KSSL data.

Usage

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KSSL_VG_model(VG_params, phi_min = 10^-6, phi_max = 10^8, pts = 100)

Arguments

VG_params

a data.frame or list object with the parameters of the van Genuchten model, see details

phi_min

lower limit for water potential in KPa

phi_max

upper limit for water potential in KPa

pts

number of points to include in estimated water retention curve

Details

This function was developed to work with measured or estimated parameters of the van Genuchten model, as generated by the Rosetta model. As such, VG_params should have the following format and conventions:

theta_r

saturated water content, values should be in the range of {0, 1}

theta_s

residual water content, values should be in the range of {0, 1}

alpha

related to the inverse of the air entry suction, function expects log10-tranformed values with units of cm

npar

index of pore size distribution, function expects log10-tranformed values with units of 1/cm

Value

A list with the following components:

VG_curve

estimated water retention curve: paired estimates of water potential and water content

VG_inverse_function

function for converting measured water content (theta, units of percent, range: {0, 1}) to estimated water potential (phi, units of KPa)

Note

A practical example is given in the fetchSCAN tutorial.

Author(s)

D.E. Beaudette

References

water retention curve estimation

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

Examples

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# basic example
d <- data.frame(theta_r=0.0337216, 
theta_s=0.4864061, 
alpha=-1.581517, 
npar=0.1227247)

vg <- KSSL_VG_model(d)

str(vg)

soilDB documentation built on Jan. 12, 2018, 1:05 a.m.