Investigation the relationship between the fractal dimension of soil particles with different types of erosion and different parent materials

Soil erosion is a global problem that reduce soil fertility and water quality Proper evaluation of the factor’s affecting erosion is the first step in choosing solution to reduce and control this destructive phenomenon. Important parameters that can be examined in this issue are soil texture, size and quality soil grains and type of bedrock, which can affect the soil erodibility coefficient. Fractal dimension (Df) of particle size distribution (PSD) and fractal dimension of aggregate size distribution (ASD) have been introduced as a predictor of soil texture-related properties. The purposes of this study were to investigate the relations between fractal dimension and various forms of erosion, including surface erosion, rill and badland, also to investigate the relations between fractal dimension and various forms of bedrock and to study the mean weight diameter (MWD), aggregate stability (AS) and aggregate degradation (PAD). Fractal dimension was computed by Yong and Crawford model using the data of particle size distribution experiments by the method of wet and dry sieve and aggregate size distribution by submerged sieve method. Bulk density by weighted method and specific surface area by EGME method were determined. The results of statistical analysis showed that different forms of erosion and bedrock are related to the fractal dimension. In other words, with the development of the erosion form, the fractal dimension increased, so badland had the highest and surface erosion had the smallest fractal dimension. Also, among various bedrocks, with decrease in resistance and increase in erodibility, Df was increased. In addition, fractal dimension had a positive correlation with MWD and AS and negative correlation with PAD. Finally, it can be concluded that due to the ease of calculating the fractal dimension of soil and its proper relationship with erosion, this index can be used in the quantitative and qualitative assessment of soil erosion.