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Several conceptual models have been developed with different levels of complexity (e.g., equivalent continuum, dual porosity, and dual permeability approaches) to describe the macropore flow-transport process. However, no congruent conceptual model with a corroborating measurement technique is available to precisely describe this process. As gravity and/or capillary forces dominate the transport processes in the porous medium near saturation, various factors contribute to the initition of macropore flow and its intensity, including pore geometry and continuity. In addition to soil energy status, the nature of top and bottom boundary conditions and textural layering, play important roles. We quantified the effects of many of these factors on preferential flow and transport in a review of carefully controlled column experiments using novel designs. Exisiting dual permeabiltiy conceptual meodels were tested with the new data sets, ultimately leading to the formulation of more realistic preferential flow models that contain physically-based and measureable parameters.