Unstable Wetting Fronts in Water-Repellent Field Soils

Study objectives are to (i) investigate the effects of a water-repellent top layer on water flow and solute transport and (ii) examine whether unstable wetting front theories can be used to predict the occurrence of preferential flow in water-repellent field soils. The study took place on two adjacent plots with grasscover near Ouddorp (The Netherlands)-one plot with a water-repellent top layer, the other plot with a wettable top layer. The soil at the experimental site is a sand soil of marine orgin-mesic Typic Psammaquent []