Wetting Front Instability in the Vadose Zone of New Mexico's Soils

摘要

Field experiments were conducted in the Sevilleta dunes approximately 20 milesnorth of Socorro, New Mexico. After water application, the depth and stability of the wetting front was observed by digging an observation pit. Contrary to unstable wetting front theories in 1992, no instabilities were encountered and all wetting fronts appeared quite stable. Lysimeter experiments were conducted in the laboratory to validate current wetting front instability theories with four different grades of sieved and air-dried perlite and quartz sand. Water was applied by a sprinkler system at rates within the range of natural precipitation rates in New Mexico. The experimental results show that wetting front instability will cause fingering phenomena in a homogenous soil system. The authors used their laboratory results to develop a simple approach for evaluating wetting front stability in dry soils. The application of stability criteria is demonstrated with a case study from the Sevilleta dunes near Socorro, NM.