HR: 09:25h
AN: H41H-06    [Abstracts]
TI: Gravity Driven Fingering and its Connection to Pore Scale Network Modeling
AU: * DiCarlo, D A
EM: ddicarlo@ars.usda.gov
AF: USDA/ARS National Sedimentation Laboratory, PO BOX 1157 598 McElroy Dr, Oxford, MS 38655 United States
AB: Gravity driven fingering through porous media can cause extremely fast transport of contaminants to ground and surface waters as much of the filtering effects of the medium are bypassed. In uniform porous media this fingering has been shown to be caused by anomalous infiltration behavior called saturation overshoot where the saturation at the front of the infiltration is higher than the saturation at the tail of the infiltration. In this talk we will show how physically-based network model predicts the onset and range of saturation overshoot for different sized media and initial water content. The network model is based on recent pore-scale studies and includes pore and throat elements of different shapes and sizes, a connection topology based on geologic media, and entry pressures modified by viscous effects. Thus we argue that saturation overshoot and the associated field-scale gravity driven fingering are a result of the microscopic discreteness of the pores and throats of the porous medium.
DE: 1838 Infiltration
DE: 1847 Modeling
DE: 1866 Soil moisture
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: Fall Meeting 2005