Estimation of Soil- Water Retention Curve Using Readily Available Soil Properties Based on Fractal Approach

To obtain in a laboratory retention curve is not cost and time effective. So estimation of soil moisture using basic soil properties is of importance. The objective of this study was to calculate the soil-water retention curve using the readily available parameters of soil, fractal geometry. In order to calculate the fractal dimension in the TW type( )  model from readily available parameters of soils, four methods were used based on (1) clay percentage with non-linear equation, (2) clay, sand and silt percentage, (3) clay percentage with logarithmic equation, and (4) the fractal dimension of particles obtained from clay, silt and sand. 30 soil samples with different texture including loam, clay loam, clay, sandy clay loam, silty loam and sandy loam from the northern part of Iran were used to evaluate fractal functions.  had the maximum value of 2.909 in clay soil and the minimum value of 2.731 in sandy loam soil and average of 2.817. The average fractal dimension obtained by the first, second, third and fourth methods were 2.84, 2.86, 2.75 and 2.82, respectively. NRMSE value of the first method was 0.0160, the second method was 0.0093, the third method was 0.0216 and the fourth method was 0.0089. The results showed that except for the method based on the percentage of sand, silt and clay, the results of the other methods are close to each other.