Open AccessUnstable Flow in Repellent and Sub-critically Repellent Soils: Theory and Management Implications
Author(s) -
Rony Wallach,
Tammo S. Steenhuis,
Ellen R. Graber,
David A. DiCarlo,
Yves Parlange
Publication year - 2012
Language(s) - English
Resource type - Reports
DOI - 10.32747/2012.7592643.bard
Subject(s) - macropore , soil water , wetting , ponding , water repellent , water flow , environmental science , soil science , penetration (warfare) , flow (mathematics) , colloid , geotechnical engineering , hydrology (agriculture) , chemistry , geology , mathematics , materials science , chemical engineering , engineering , drainage , geometry , ecology , mesoporous material , biochemistry , operations research , composite material , biology , catalysis
Water repellency causes unstable wetting fronts that result in water moving in preferential flowpaths through homogeneous soils as well in structured soils where macropores enhance the preferential flow pattern. Water repellency is typically associated with extended water ponding on the soil surface, but we have found that repellency is important even before the water ponds. Preferential flow fingers can form under conditions where the contact angle is less than 90o, but greater than 0o. This means that even when the soil is considered wettable (i.e., immediate penetration of water), water distribution in the soil profile can be significantly non-uniform. Our work concentrated on various aspects of this subject, with an emphasis on visualizing water and colloid flow in soil, characterizing mathematically the important processes that affect water distribution, and defining the chemical components that are important for determining contact angle. Five papers have been published to date from this research, and there are a number of papers in various stages of preparation.