Comparison of Two Physically Capillary-Adsorption Based Models for Estimation of Unsaturated Hydraulic Conductivity at Both Near Dry and Saturated Water Contents

Document Type : Original Article

Authors

1 MSc Student, Department of Irrigation and Reclamation, College of Agriculture and Natural Resources, University of Tehran, Iran

2 Professor, Irrigation and Reclamation Department, College of Agriculture and Natural Resources, University of Tehran, Iran.

3 Researcher at the Department of Irrigation and Reclamation Engineering, University of Tehran

Abstract

It has been documented that the assumption of capillary movement of water in a bundle of cylindrical tubes often leads to systematically underestimation of soil unsaturated hydraulic conductivity at low potentials which is due to ignoring the contribution of adsorptive forces and liquid films. In this study, the performance of two physical models of (Tuller-Or) and (Lebeau-Konrad) that take into account the contribution of both adsorptive and capillary forces and the well-known capillary-based model of (Van Genuchten-Mualem) for modeling the soil-water retention curve and estimation of the unsaturated hydraulic conductivity were evaluated. To that end, experimental data gathered from literature including six soils that cover a broad range of texture and hydraulic behavior. The results showed the superiority of the two capillary-adsorption models over the capillary-based Van Genuchten-Mualem model in estimating the soil-water characteristic curve and unsaturated hydraulic conductivity. Among the two physically capillary-adsorption based models, the Lebeau-Konrad model performed better. The results showed that the Lebeau-Konrad model underestimates the hydraulic conductivity of clayey soils in the near saturation range and the best performance of the Tuller-Or model was shown to be for loamy soils. Because the Tuller-Or model is the most comprehensive and physics-based model for modeling the unsaturated hydraulic conductivity up to date, future studies should be devoted to improving the flexibility of this model via extending the model to other pore size distribution than the original Gamma distribution, such as lognormal, incomplete gamma and Weibull distributions.

Keywords


Birdsell, D. T., Rajaram, H., Dempsey, D., & Viswanathan, H. S. 2015. Numerical model of hydraulic fracturing fluid transport in the subsurface with pressure transient and density effects. In 49th US Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Association.
Burdine, N. 1953. Relative permeability calculations from pore size distribution data. Journal of Petroleum Technology. 5(03): 71-78.
Campbell, G. S., & Shiozawa, S. 1992. Prediction of hydraulic properties of soils using particle-size distribution and bulk density data. Indirect methods for estimating the hydraulic properties of unsaturated soils, 317-328.
Ghanbarian, B., Hunt, A. G., Skinner, T. E., & Ewing, R. P. 2015. Saturation dependence of transport in porous media predicted by percolation and effective medium theories. Fractals. 23(01): 1540004.
Hunt, A. G., Ewing, R. P., & Horton, R. 2013. What's wrong with soil physics?. Soil Science Society of America Journal. 77(6): 1877-1887.
Kosugi, K. I. 1996. Lognormal distribution model for unsaturated soil hydraulic properties. Water Resources Research. 32(9): 2697-2703.
Lebeau, M., & Konrad, J. M. 2010. A new capillary and thin film flow model for predicting the hydraulic conductivity of unsaturated porous media. Water Resources Research. 46(12).
Mualem, Y. 1976a. A new model for predicting the hydraulic conductivity of unsaturated porous media. Water resources research. 12(3): 513-522.
Mualem, Y. 1976b. A catalogue of the hydraulic properties of unsaturated soils.
Nemes, A. D., Schaap, M. G., Leij, F. J., & Wösten, J. H. M. 2001. Description of the unsaturated soil hydraulic database UNSODA version 2.0. Journal of Hydrology. 251(3-4): 151-162.
Or, D., & Assouline, S. 2013. The foam drainage equation for unsaturated flow in porous media. Water Resources Research. 49(10): 6258-6265.
Or, D., & Tuller, M. 1999. Liquid retention and interfacial area in variably saturated porous media: Upscaling from single‐pore to sample‐scale model. Water Resources Research. 35(12): 3591-3605.
Or, D., & Wraith, J. M. 1999. Temperature effects on soil bulk dielectric permittivity measured by time domain reflectometry: A physical model. Water Resources Research. 35(2): 371-383.
Pachepsky, Y. A., Shcherbakov, R. A., Varallyay, G., & Rajkai, K. 1984. On obtaining soil hydraulic conductivity curves from water retention curves. Pochvovedenie. 10: 60-72.
Philip, J. R. 1977. Unitary approach to capillary condensation and adsorption. The Journal of Chemical Physics. 66(11): 5069-5075.
Purcell, W. R. 1949. Capillary pressures-their measurement using mercury and the calculation of permeability therefrom. Journal of Petroleum Technology. 1(02): 39-48.
Sadeghi, M., Ghahraman, B., Ziaei, A. N., Davary, K., & Reichardt, K. 2012. Invariant solutions of Richards' equation for water movement in dissimilar soils. Soil Science Society of America Journal. 76(1): 1-9.
Sakai, M., Toride, N., & Šimůnek, J. 2009. Water and vapor movement with condensation and evaporation in a sandy column. Soil Science Society of America Journal. 73(3): 707-717.
Sleutel, S., Cnudde, V., Masschaele, B., Vlassenbroek, J., Dierick, M., Van Hoorebeke, L., ... & De Neve, S. 2008. Comparison of different nano-and micro-focus X-ray computed tomography set-ups for the visualization of the soil microstructure and soil organic matter. Computers & Geosciences. 34(8): 931-938.
Tiktak, A., Hendriks, R. F. A., Boesten, J. J. T. I., & Van der Linden, A. M. A. 2012. A spatially distributed model of pesticide movement in Dutch macroporous soils. Journal of hydrology. 470: 316-327.
Tuller, M., & Or, D. 2001. Hydraulic conductivity of variably saturated porous media: Film and corner flow in angular pore space. Water Resources Research. 37(5): 1257-1276.
Tuller, M., & Or, D. 2002. Unsaturated Hydraulic Conductivity of Structured Porous MediaA Review of Liquid Configuration–Based Models. Vadose Zone Journal: 1(1): 14-37.
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.
Weber, T. K., Iden, S. C., & Durner, W. 2017. Unsaturated hydraulic properties of Sphagnum moss and peat reveal trimodal pore‐size distributions. Water Resources Research. 53(1): 415-434.
Wraith, J. M., & Or, D. 1998. Nonlinear parameter estimation using spreadsheet software. Journal of Natural Resources and Life Sciences Education. 27(1): 13-19.
Wyllie, M. R. J., & Gardner, G. H. F. 1958. The generalized kozeny-carman equation. World oil. 146(4): 121-128.
Zhao, Y., Hu, X., & Li, X. 2020. Analysis of the intra-aggregate pore structures in three soil types using X-ray computed tomography. CATENA. 193: 104622