Preferential Flow in the Field Soils

Abstract. Preferential flow has been increasingly recognized as a process of great practical significance for the transport of water and contamination in field soils. Recently, fractal has been applied to characterize the geometry of stain patterns of soil profiles. The field experiment involved loamy and sandy soils. The sequence of images of horizontal cross-sections of stain patterns in the two soils suggest that fingering occurred in the loamy soil, not in the sandy soil. Yet, the surface fractal dimensions of the stain patterns are very similar in both cases. This similarity suggests that these dimensions provide information not so much on the geometry of the stain patterns but more directly on the fractal properties of the pore network in the soil. This viewpoint is confirmed partially by the evidence of a good correlation between the surface fractal dimension and the exponent of a Van Genuchten expression applied to the particle size distribution of the soil. 1