Abstract

Direct measurement of soil water retention curve (SWRC) is time consuming and expensive, therefore many empirical models have been developed to describe it. Also fractal models have been proposed in the last decades for estimating SWRC. In this study, the fractal dimension of SWRC (D_SWEC) and the mass fractal dimension of soil texture for 30 soil samples (with a spread range of soil texture) were determined. Fractal dimension of soil texture and a relationship among the fractal dimension of SWRC, Soil texture data and bulk density in a fractal base model was used to estimate SWRC, as it was estimated by Campbell empirical model. The estimated results were compared with the validation data set for validation and model comparison. The results indicated that the fractal base model was capable of predicting SWRC with reasonable accuracy, also the difference between estimation results of fractal base models and Campbell empirical model decrease when the fractal dimension of soil texture D_texture was used, instead of D_SWEC. The estimation of D_SWRC by using of clay and silt content and soil bulk density as a regression relationship had better results than the fractal dimension of soil texture as replacement of D_SWRC was used in the fractal model. Therefore, it could be used for estimating SWRC, using easily measured data.

Key words: Fractal, soil water retention curve, estimation.