Estimation of soil water retention curve using fractal dimension

Abstract

The soil water retention curve (SWRC) is a fundamental hydraulic property majorly used to study flow transport in soils and calculate plant-available water. Since, direct measurement of SWRC is time-consuming and expensive, different models have been developed to estimate SWRC. In this study, a fractal-based model was developed to predict SWRC. A wide range of soil textures (130 soil samples) was used to determine the fractal dimension of SWRC (D_SWRC). Moreover, the SWRC pedotransfer functions were established based on easily available soil properties such as particle size distribution and bulk density by applying multiple linear regression analysis. The measured D_SWRC for 110 soil samples was considered for function parameterization and the remaining was used for model validation. The results illustrated that the D_SWRC linearly correlates with clay and silt contents and soil bulk density (r² = 0.909). The SWRC can, therefore, be easily and concisely estimated by the proposed fractal-based functions.

Keywords: Fractal model; Pedotransfer functions; Regression analysis; Soil water retention curve