Modeling of leakage through cracked clay liners -II: a new perspective

: An hydraulic description of moisture transport through the compacted clay layers of a landfill cover liner is presented. Previous descriptions have assumed that micro-pore processes control the transport. The present description incorporates the influence of voids or macro-pores created by desiccation cracking. The existence and importance of cracks is documented using laboratory and field data. Although micro-pore flow can be modeled confidently using Darcy's Law, the contribution of macro-pore flow is often neglected because of the lack of field verified models to describe its occurrence. The variety of modes and mechanisms of flow that are operative in flow through cracked clay liners is discussed, and analogies are made to familiar concepts in open channel flow theory. The discussion provides the conceptual framework for the development of a numerical model to simulate both the micro- and macro-pore flow phenomena.