3RD INTERNATIONAL CONGRESS ON TECHNOLOGY - ENGINEERING & SCIENCE - Kuala Lumpur - Malaysia (2017-02-09)

Flow And Distribution Of Water In Unsaturated, Fractionally-wet Porous Media Systems

In recent years, interest in fluid flow and transport in the unsaturated zone has taken on increased importance because of the growing concern that the quality of the subsurface environment is being adversely affected by agricultural, industrial and municipal activities. The wettability properties (e.g., water repellency) of the porous media play an important role in determining fluid movement and ultimate distributions. Research studies have shown that preferential flow is likely to occur in water repellant soils resulting in spatial variability (over multiple scales) in the soil moisture. [1] The preferential flow paths can result in fast and deep infiltration of water and may impact solute and colloid/virus transport and plant growth. Numerical modeling of unsaturated flow through water-wet systems is complex due to the natural heterogeneities and number of constitutive relations (e.g., capillary pressure – water content, relative permeability) that must be determined when using conventional techniques such as Richard’s equation. Development of the appropriate relations for the modeling becomes even more difficult in systems that contain water repellant soils due to the complexity of the processes at the pore-scale. Even in cases where proper constitutive relations can be developed, these relations do not account for the heterogeneous water distributions at the pore- and cm-scale that occur following drainage; distributions that can have an impact on later infiltration paths and evaporation/volatilization. This paper will results in better understanding of the flow and distribution of water in unsaturated, fractionally-wet (or water repellant soils) porous media systems where a series of capillary pressure – water content curves for both drainage and imbibition processes will be measured in the laboratory for a number of different media sizes/gradations and wettability conditions in order to develop the necessary constitutive relations.
zaydoun abusalem