Abstract. The study of water movement in soils is of fundamental\ud
importance in hydrologic science. It is generally\ud
accepted that in most soils, water and solutes flow through\ud
unsaturated zones via preferential paths or fingers. This\ud
paper combines magnetic resonance imaging (MRI) with\ud
both fractal and multifractal theory to characterize preferential\ud
flow in three dimensions. A cubic double-layer column\ud
filled with fine and coarse textured sand was placed\ud
into a 500 gauss MRI system. Water infiltration through\ud
the column (0.15×0.15×0.15m3) was recorded in steady\ud
state conditions. Twelve sections with a voxel volume\ud
0.1×0.1×10mm3 each were obtained and characterized using\ud
fractal and multifractal theory. The MRI system provided\ud
a detailed description of the preferential flow under steady\ud
state conditions and was also useful in understanding the dynamics\ud
of the formation of the fingers. The f ( ) multifractal\ud
spectrum was very sensitive to the variation encountered\ud
at each horizontally-oriented slice of the column and provided\ud
a suitable characterization of the dynamics of the process\ud
identifying four spatial domains. In conclusion, MRI\ud
and fractal and multifractal analysis were able to characterize\ud
and describe the preferential flow process in soils. Used\ud
together, the two methods provide a good alternative to study\ud
flow transport phenomena in soils and in porous media.CIDA-Canada through the ALTAGRO ProjectFAPESP (07/58561-7
