Water retention curve modeling via van Genuchten model and KSSL data.
KSSL_VG_model(VG_params, phi_min = 10^6, phi_max = 10^8, pts = 100)
VG_params 


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 
A list with the following components:
estimated water retention curve: paired estimates of water potential (phi) and water content (theta)
spline function for converting water potential (phi, units of kPa) to estimated volumetric water content (theta, units of percent, range: {0, 1})
spline function for converting volumetric water content (theta, units of percent, range: {0, 1}) to estimated water potential (phi, units of kPa)
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:
saturated water content, values should be in the range of {0, 1}
residual water content, values should be in the range of {0, 1}
related to the inverse of the air entry suction, function expects log10transformed values with units of cm
index of pore size distribution, function expects log10transformed values with units of 1/cm
A practical example is given in the fetchSCAN tutorial.
water retention curve estimation
D.E. Beaudette
# 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)#> List of 3 #> $ VG_curve :'data.frame': 100 obs. of 2 variables: #> ..$ phi : num [1:100] 1.00e06 1.38e06 1.92e06 2.66e06 3.68e06 ... #> ..$ theta: num [1:100] 0.486 0.486 0.486 0.486 0.486 ... #> $ VG_function :function (x, deriv = 0L) #> $ VG_inverse_function:function (x, deriv = 0L)