Marcel Schaap, Soil Water and Env Science, University of Arizona, Tucson, AZ 85721, Markus Tuller, Department of Soil Water & Environmental Science, The University of Arizona, Tucson, AZ 85721, Andrey Guber, USDA-ARS, Dep. of Earth and Environmental Sciences UCA, 173 Powder Mill Rd. BARC-East, Beltsville, MD 20705, and Yakov Pachepsky, Bldg.173 Rm. 203 Powder Mill Road, USDA-ARS, USDA/ARS, BA/ANRI/ESML/BARC-East, Beltsville, MD 20705.
Macropore flow in soils is a conceptually reasonably well understood phenomenon, but very hard to quantify exactly. Difficulties arise because of experimental complexities that require large samples, pore geometry and pore-network effects, and because of uncertainties in the interactions between macro-pores and the surrounding soil matrix. In this presentation we report on a dataset where saturated macropore flow was measured in soil columns of which pore geometry was subsequently observed with computed tomography (CT). Segmentation of the three-dimensional CT images into solid phase, and pore-space allow us to study the statistical properties of the pore-network. Finally, lattice Boltzmann simulations of Navier-Stokes flow in the pore network allow us to compute saturated hydraulic conductivity and compare these results to the observed data.