Relationship Between Fractal Dimension of Particle Size Distribution and Some Physical Properties of Soils

Fractal dimension (Dm) of particle size distribution (PSD) has been introduced as a predictor of soil texture-related properties. This study investigates relationships between Dm and some of the physical properties of soils. Samples from 36 soil series with varying properties were collected from northwest of Iran. Sand fraction was determined by sieving, and silt and clay fractions by the hydrometer methods. Fractal dimension of PSD was computed by Bird et al. model. Organic matter content and total porosity of the samples were measured by wet oxidation and gravimetric methods, respectively. A rainfall simulator with drainable tilting flume (1×0.5 m) at 9% slope was employed and the effective hydraulic conductivity (Ke) was calculated at 20, 37, and 47 mm h-1 rainfall intensities. Statistical analysis showed that in contrast to significant and positive correlations occurred between Dm and each of clay (0.963**), silt (0.371**) and total porosity (0.642**), the correlations between Dm and either of sand (0.748**) or geometric mean diameter of particles (dg) were negative (0.748**). Therefore, Dm had significant relations with soil textural fractions and textural classes, and might be used as an integrating index in modeling studies. Results also showed that greater Dm was associated with greater self-similarity in pore size distribution.