<abstract xmlns="http://www.w3.org/1999/xhtml">The relative hydraulic conductivity curve <italic>K</italic><italic>r</italic>(<italic>h</italic>) <italic>= K</italic>/<italic>K</italic><italic>s</italic> is a key variable in soil modeling. This study proposes a model to represent <italic>K</italic><italic>r</italic>(<italic>h</italic>), the so-called Gardner dual (GD) model, which extends the classical Gardner exponential model to h values greater than <italic>h</italic>o, the suction value at the inflection point of the <italic>K</italic><italic>r</italic>(<italic>h</italic>) curve in the log-log scale. The goodness of fit of GD using experimental data from UNSODA was compared to that of the MVG [two-parameter (<italic>K</italic><italic>ro</italic>, <italic>L</italic>) Mualem-van Genuchten] model and a corresponding modified MVG model (MVGm). In 77 soils without evidence of macropore flow, GD reduced the RMSE errors by 64% (0.525 to 0.191) and 29% (0.269 to 0.193) in relation to MVG and MVGm, respectively. In the remaining 76 soils, GD generally was less accurate than MVG and MVGm, since most of these soils presented evidence of macropore flow (dual permeability). GD has three parameters and two degrees of freedom, like MVG. Two of them allow the calculation of the macroscopic capillary length, a parameter from the infiltration literature. The three parameters are highly dependent on the <italic>K</italic><italic>r</italic>(<italic>h</italic>) data measurement in a short wet suction range around <italic>h</italic>o, which is an experimental advantage.</abstract>

The relative hydraulic conductivity curve Kr(h) = K/Ks is a key variable in soil modeling. This study proposes a model to represent Kr(h), the so-called Gardner dual (GD) model, which extends the classical Gardner exponential model to h values greater than ho, the suction value at the inflection point of the Kr(h) curve in the log-log scale. The goodness of fit of GD using experimental data from UNSODA was compared to that of the MVG [two-parameter (Kro, L) Mualem-van Genuchten] model and a corresponding modified MVG model (MVGm). In 77 soils without evidence of macropore flow, GD reduced the RMSE errors by 64% (0.525 to 0.191) and 29% (0.269 to 0.193) in relation to MVG and MVGm, respectively. In the remaining 76 soils, GD generally was less accurate than MVG and MVGm, since most of these soils presented evidence of macropore flow (dual permeability). GD has three parameters and two degrees of freedom, like MVG. Two of them allow the calculation of the macroscopic capillary length, a parameter from the infiltration literature. The three parameters are highly dependent on the Kr(h) data measurement in a short wet suction range around ho, which is an experimental advantage.

Extension of the Gardner exponential equation to represent the hydraulic conductivity curve

Department of Water Resources and Environment, Politechnical School

Federal Univ. of Rio de Janeiro (CT/UFRJ)

Department of Hydrology, Geological Survey of Brazil (CPRM)

Journal of Hydrology and Hydromechanics

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

The relative hydraulic conductivity curve Kr(h) = K/Ks is a key variable in soil modeling. This study proposes a model to represent Kr(h), the so-called...

Extension of the Gardner exponential equation to represent the hydraulic conductivity curve

Published Online: Nov 15, 2019

Page range: 359 - 371

Received: Dec 07, 2018

Accepted: Mar 27, 2019

DOI: https://doi.org/10.2478/johh-2019-0015

Keywords
Hydraulic conductivity curve, Gardner exponential model, Mualem-van Genuchten model

© 2019 Theophilo B. Ottoni Filho et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Extension of the Gardner exponential equation to represent the hydraulic conductivity curve

Published Online: Nov 15, 2019

Page range: 359 - 371

Received: Dec 07, 2018

Accepted: Mar 27, 2019

DOI: https://doi.org/10.2478/johh-2019-0015

KeywordsHydraulic conductivity curve, Gardner exponential model, Mualem-van Genuchten model

© 2019 Theophilo B. Ottoni Filho et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Hydraulic conductivity curve, Gardner exponential model, Mualem-van Genuchten model