A significant number of subsurface environmental problems involve preferential flow and solute transport in variable saturated media. The presence of large connected void spaces such as macropores, root holes, structural voids, channel-like opening in the vadose zone have been widely documented to provide rapid pathways for spreading of contaminants (nutrient, fertilizers, pesticides, heavy metals, NAPL), particle and microorganisms, radionuclides, from the surface to deep aquifers. This is a very complex issue in relation to predicting the fate and to the remediation of the contamination. The ability to reliably predict the rate and direction of preferential flow and contaminant transport in variable saturated media and hereby to understand the processes of these systems would be of great economic benefit for planning and implementation of the remediation of contaminated macroporous and fractured sites.
The objectives of this session is to stimulate papers dedicated to the preferential flow hydrology at applicative scales, particularly to the control of the preferential flow for sustainable land and water management. This should make possible the solution of a wide array of complex multidisciplinary problems to the improved and efficient soil use and water resources and environmental pollution.

Major subjects

This session will deal with the following topics:

1. Relation between infiltration and surface runoff in the context of preferential flow processes;
2. Relation between preferential flow patterns and soil tillage;
3. Effects of root systems on preferential flow;
4. Relation between preferential flow and physical-chemical soil properties;
5. Transport of contaminants and microscopic organisms by preferential flow;
6. Soil particles transport via preferential flow to drainage systems and groundwater;
7. Carbon, nitrogen and phosphate dynamics in preferential flow paths in agricultural and forest soils;
8. Advanced techniques for visualizing preferential flow pathways at applicative scales (georadars and geoelectric techniques, …);
9. Theoretical approaches and experimental evidences of preferential flow and transport in lysimeters, along hillslopes and to drainage systems.