Ku: Unsaturated hydraulic conductivity

In SoilHyP: Soil Hydraulic Properties

Unsaturated hydraulic conductivity

Description

Calculates unsaturated hydraulic conductivity for a given suction for unimodal or bimodal van Genuchten-Mualem (vg/vgm), Peters-Durner-Iden (PDI) and Brooks and Corey (bc) (only unimodal) parameterisation.

Usage

Ku(suc, FUN.shp = "vG", par.shp, modality = "uni", suc.negativ = TRUE)

Arguments

suc	Suction/pressure heads. Negative if suc.negativ = TRUE
FUN.shp	Funktion for soil hydraulic properties (vGM or PDI) (see details)
par.shp	named parameter in list or vector
modality	pore size distribution ('uni' or 'bi')
suc.negativ	set TRUE if suction/pressure heads are negative and FALSE if positive

Details

FUN.shp:

vGM: van Genuchten-Mualem (uni or bimodal) ('vg' works aswell)
PDI: Peters-Durner-Iden with van Genuchtens saturation function (uni or bimodal)
bc: Brooks and Corey (unimodal)

par.shp (vG and PDI):

ths [-]: saturated water content
thr [-]: residual water content
alfa [1/L]: van Genuchten shape parameter
n [-]: van Genuchten shape parameter
m [-]: shape parameter (m = 1-(1/n) if missing)
Ks [L/time]: saturated hydraulic conductivity
tau [-]: tortuosity and connectivity parameter (minimum -1 or -2 for the PDI model; see Peters (2014) for details)

par.shp (additional parameter for 'PDI'):

omega: weighting between relative capillary and film conductivity
h0 [L]: suction at water content of 0 (i.e. oven dryness) (h0 = 10^6.8 if missing, corresponding to oven dryness at 105°C (Schneider and Goss, 2012))
a: slope at the log scale (a = -1.5 if missing as suggested by Tokunaga (2009) and Peters (2013))

par.shp (additional parameter for bimodal (modality = 'bi')):

w2 [-]: weigthing between pore space distributions
alfa2 [1/L]: van Genuchten parameter alfa for second pore space distribution
n2 [-]: van Genuchten parameter n for second pore space distribution

par.shp (BC):

ths [-]: saturated water content
thr [-]: residual water content
alfa [1/L]: inverse of the air-entry value or bubbling pressure
lambda [-]: pore size distribution index
tau [-]: tortuosity and connectivity parameter (minimum -1 or -2 for the PDI model; see Peters (2014) for details)

most input works for upper- and lowercase letters

Value

unsaturated hydraulic conductivity (ku)

Author(s)

Ullrich Dettmann

References

Van Genuchten, M. T. (1980). A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil science society of America journal, 44(5), 892-898.

Mualem, Y. (1976). A new model for predicting the hydraulic conductivity of unsaturated porous media. Water resources research, 12(3), 513-522.

Peters, A. (2013). Simple consistent models for water retention and hydraulic conductivity in the complete moisture range. Water Resour. Res. 49, 6765–6780. physics-a review. Vadose Zone J. http://dx.doi.org/10.2136/vzj2012.0163.

Iden, S., Durner, W. (2014). Comment to Simple consistent models for water retention and hydraulic conductivity in the complete moisture range by A. Peters. Water Resour. Res. 50, 7530–7534.

Peters, A. (2014). Reply to comment by S. Iden and W. Durner on Simple consistent models for water retention and hydraulic conductivity in the complete moisture range. Water Resour. Res. 50, 7535–7539.

Tokunaga, T. K. (2009), Hydraulic properties of adsorbed water films in unsaturated porous media, Water Resour. Res., 45, W06415, doi: 10.1029/2009WR007734.

Priesack, E., Durner, W., 2006. Closed-form expression for the multi-modal unsaturated conductivity function. Vadose Zone J. 5, 121–124.

Durner, W. (1994). Hydraulic conductivity estimation for soils with heterogeneous pore structure. Water Resources Research, 30(2), 211-223.

Schneider, M., & Goss, K. U. (2012). Prediction of the water sorption isotherm in air dry soils. Geoderma, 170, 64-69.

Brooks, R.H., and A.T. Corey (1964): Hydraulic properties of porous media. Hydrol. Paper 3. Colorado State Univ., Fort Collins, CO, USA.

See Also

SWC and Sat

Examples

# --------------------------------------------
#  Unimodal van Genuchten
# --------------------------------------------
Ku(suc = seq(1, 1000, by = 1), FUN.shp = 'vGM',
   par.shp = list(Ks = 10, ths = 0.5, thr = 0, alfa = 0.02, n = 1.5, tau = 0.5),
   modality = 'uni', suc.negativ = FALSE)
# --------------------------------------------
#  Bimodal van Genuchten
# --------------------------------------------
Ku(suc = seq(1, 1000, by = 1), FUN.shp = 'vGM',
   par.shp = list(Ks = 10, ths = 0.5, thr = 0, alfa = 0.02,
   n = 1.5, tau = 0.5, w2 = 0.1, alfa2 = 0.1, n2 = 3),
   modality = 'bi', suc.negativ = FALSE)
# --------------------------------------------
#  Unimodal Peters-Durner-Iden (PDI)
# --------------------------------------------
Ku(suc = seq(1, 1000, by = 1), FUN.shp = 'PDI', modality = 'uni',
   par.shp = list(Ks = 10, ths = 0.5, thr = 0, alfa = 0.02, n = 1.5, tau = 0.5, omega = 0.001),
   suc.negativ = FALSE)
# --------------------------------------------
#  Brooks and Corey (BC) (only unimodal)
# --------------------------------------------
Ku(suc = seq(1, 1000, by = 1), FUN.shp = 'bc', modality = 'uni',
   par.shp = list(ths = 0.4, thr = 0, lambda =  0.211, alfa = 0.1, tau = 0.5, ks = 10),
   suc.negativ = FALSE)
# --------------------------------------------

SoilHyP documentation built on Feb. 16, 2023, 7:06 p.m.