Estimating the some hydraulic characteristics of soil using fractal dimension of solid particles

Although direct methods are used for measuring the soil hydraulic properties, but they are time consuming, difficult and the costing. This research was performed to estimate soil hydraulic characteristics using fractal dimension of solid particles in 40 soil samples. After determining soil texture and bulk density, soil moisture was measured at 9 pressure heads 0, 10, 30, 50, 100, 300, 500, 1000, and 1500 KPa. The above parameters were used for determining the parameters of Van Genuchten equation (m and α) in RETC software. Also fractal dimension of solid particles was determined based on clay percentage it was used for estimating the moisture contents in Brooks and Corey and Van Genuchten equations. The results showed that correlation coefficient values between measured and estimated soil moisture contents were slightly high in all soil texture classes, i.e. silty clay, loam and sandy loam and the precision of models in estimating soil moisture contents of silty loam classes was higher than other classes. Also, using of fractal dimension for estimating the m and α parameters of Van Genuchten equation had the high precision in all 3 soil textures and similar to soil moisture contents, the precision of these estimated parameters in silty clay soil texture class was more than loam and sandy loam classes. In general, the results of this research showed that using of fractal dimension for estimation the hydraulic characteristics has a high validation in fine and slightly moderate soil textures, and its efficiency is low in moderate and coarse textures.