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This paper presents the use of software modelling as a tool to study the impact of hydraulic "resistivity" on the contaminant transport through bentonite-based containment barriers. A sensitivity analysis on the predicted data was carried out by varying the boundary conditions as well as the hydraulic resistance to flow through varying contaminant transport parameters. Accordingly, both advective and diffusive flow processes are considered as that which resists the flow. In particular, the effect on the contaminant migration due to desiccation cracking is explored. Laboratory evidence is provided and discussed to show how the initial microstructure of the clay influences the development of subsequent macro structural features such as shrinkage crack patterns. The effect of these cracks and the intensity of cracking on the contaminant migration are modelled and pragmatically discussed. Additionally, the effect on the hydraulic conductivity of bentonite-based barriers, when permeated with non-standard liquids is discussed and a typical analytical output is presented.

Moisture desorption observations from two bentonite clay mats subjected to ten 26 environmental zones with individually different combinations of laboratory controlled constant 27 temperatures (between 20⁰C to 40⁰C) and relative humidity (between 15% to 70%) are presented. 28These laboratory observations are compared with predictions from mathematical models, such as 29Thin-layer drying equations and kinetic drying models proposed by Page, Wang and Singh, and 30Henderson and Pabis. The quality of fit of these models is assessed using standard error of 31 estimate, relative percent of error and coefficient of correlation. The Page model was found to 32 better predict the drying kinetics of the bentonite clay mats for the simulated tropical climates. 33Critical study on the drying constant and moisture diffusion coefficient help to assess the efficacy 34 of a polymer to retain moisture and control desorption through water molecule bonding. This is 35 further substantiated with the Guggenheim-Aderson-DeBoer (GAB) desorption isotherm model 36 which is presented. 37 38