Tuesday, November 6, 2007
184-7

Observing and Simulating Macropore Flow with Computed Tomography and Lattice Boltzmann Methods.

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.