Preferential Flow and Transport in Variably Saturated Porous Media

The U.S. Geological Survey (USGS) sponsored a special session on "Preferential Flow and Transport in Variably Saturated Porous Media" at the American Geophysical Union Fall Meeting, San Francisco, California, December 5-9, 2005. This session presented information on the transport of contaminants through preferential flow paths in the unsaturated zone. Many contamination problems and issues (point source and nonpoint source) occur because contaminants have passed through the unsaturated zone before they reached ground-water resources. Therefore, understanding the transport of contaminants through the unsaturated zone is important for managers dealing with many types of contamination issues.

Session Description

Preferential flow (the non-ideal behavior of fluid flow in porous media) can be an important process that affects the transport of natural and anthropogenic chemicals in variably-saturated porous media. For many vadose-zone problems, proper inclusion of preferential flow and transport processes will be essential to successful modeling activities. This session seeks data collection and modeling papers that focus on developing preferential flow and transport models (including inverse modeling techniques), estimating spatial structures of parameters, and determining prediction uncertainties. We are especially interested in work that combines theoretical advancements from laboratory or field-scale experimental data to explore preferential flow resulting from macropores, material heterogeneity, wetting front instability, freeze/thaw, and(or) focused flow. We are also interested in analogous two-phase preferential flows such as DNAPL migration in the saturated zone.

USGS Presentations

• Three Decades of Field Experiments Show Minimal Variability in Maximum Preferential Flow Speed, by Nimmo, J.R,
• Focused Flow Near Irrigation Wells as a Possible Mechanism of Regionally Enhanced Chemical Migration in the High Plains, Central U.S., by Walvoord, M.A., USGS, Gurdak, J.J., Colorado School of Mines, McMahon, P.B., USGS
• Scaling Relations Between Laboratory and Field Scale Hysteretic Measurements for a Coarse Sandy Loam Soil, by Little, J.J., University of Colorado at Denver, Tindall, J.A., USGS, Friedel, M.J., USGS

Conveners

• James Tindall, USGS
• Michael Friedel, USGS

Session Information

• Agenda Part I
• Agenda Part II
• Full Session Description
• General Meeting Information

Information on Unsaturated Zone Hydrology

• Field Applications of Unsaturated Zone Flow Theory
• Waste Disposal and Contaminant Migration in the Arid Southwest, Amargosa Desert Research Site, Nevada
• Unsaturated Zone Field Studies
• Unsaturated Zone Flow Project
• Temperature Effects in the Unsaturated Zone

Related Headlines

• Ground-Water Recharge Affects Fate of Petroleum Contaminant Plumes
• Desert Plants Reveal Contaminant Transport Pathways
• New Model Improves Understanding of the Transport of Carbon Isotopes in the Unsaturated-Zone
• Using Plants To Detect Tritium Contamination
• High Nitrate in the Desert? What’s Going On?
• New Book on Soil Analysis Methods Destined to Become a Classic
• Are Deserts Still Drying Out Since the Ice Age?
• The Atmosphere - A Potential Source of MTBE to Ground Water

Back to Meetings Page