This research will measure and quantify the hydraulics of flow in soil macropores and the interactions between macropores and the surrounding porous media. A non-destructive gamma ray tomography unit will be used to obtain water content distributions in laboratory columns to a resolution of 5 mm during flow events and 2 mm after redistribution. A variety of pore types will be tested which will differ in size and method of formation. These direct measurements of the temporal and spatially varying soil water content will allow the calculation of flow hydraulics. Those results will in turn, be compared to existing deterministic theories of macropore flow. Specific assumptions which will be evaluated are; 1) poiseuille flow within the macropore, 2) hydraulic equilibrium between the pore and the surrounding porous media, 3) the suitability of modeling the radial sorption of water from the pore as normal horizontal sorption, and 4) the effects of surface seals on the entrance of water into the pore.
