Numerical modelling of fluid flow through unsaturated zone using a dual-porosity approach

Abstract

In this study, an attempt has been made to model fluid flow through a geological unit consisting of sandy-clay and clayey soil with significant macro pores. Considering such a geological formation using a single-continuum approach may not always be justified as the porosity and permeability contrast between the soil matrix and macro pore vary by several orders of magnitude and not by a scale factor. Under such circumstances, deducing the mean values of parameters such as porosity and permeability using conventional Representative Elementary Volume from a single continuum becomes nearly impossible. For this purpose, a numerical model has been developed to investigate the consequences of applying both equilibrium model or Single-Porosity Medium (SPM) and non-equilibrium model or Dual-Porosity Medium (DPM) approaches for the same soil types. Numerical results suggest that the depths associated with soil moisture fronts are significantly different by applying a dual continuum approach with reference to the conventional single-continuum approach.

Keywords:

• numerical modelling
• dual-porosity medium models
• pressure head
• soil moisture
• fracture
• matrix

Acknowledgement

This article was among the selected papers presented at the “Hydro-2012” conference held at IIT Bombay on 7–8 December 2012 and short-listed by Editor for publication in this Journal after re-review and revisions where necessary.