Analysis of the heterogeneous soil water flow based on the multifractal theory

Heterogeneous soil water flow was investigated by using the iodine-starch staining patterns.The field experiments were conducted at four plots with ponding water depths of 20,40,60,and 80 mm,respectively.The stained patterns of soil profiles show that soil water flow changes from the preferential flow with a few flows path and low stained coverage to the homo-geneous infiltration of the decreased unstained areas with the increase of ponding water depths.The redistribution of infiltration water is mainly influenced by the stained patterns.Flow patters are characterized by using the distributions of the maximum and actual depths.The heterogeneous soil water flow patterns from the four experiments show the multifractal nature.The flow heterogeneity is closely correlated to the multifractal spectrum.The constitutive properties of the fractal spectrum function are determined by the soil texture,whereas the range and shape of the function are affected by the nonlinearity of the heterogeneous flow.