Estimation of soil water retention curve in semi-arid areas using fractal dimension

Seyedeh Zana Mahallati,Hossein Babazadeh,Ebrahim Pazira,Fariborz Abbasi

doi:10.4314/jasem.v22i8.16

Seyedeh Zana Mahallati, Hossein Babazadeh + Show 2 more

Open Access

https://doi.org/10.4314/jasem.v22i8.16

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Abstract

The soil water retention curve (SWRC) is one of the important hydraulic functions in water flow modeling and solute transport in the porous medium. Direct measurement of SWRC is time consuming and expensive, therefore different models have been developed to describe it. In this study, a model based on fractal theory was derived to estimate water retention curve. The fractal dimension of SWRC (D SWRC ) for 130 soil samples (with a spread range of soil texture) were determined and tried to find out a simple relation between this parameter and easily available soil properties such as clay, silt and sand contents, lime percent and bulk density by applying multiple linear regression analysis. The measured D SWRC for 110 soil samples used for regression analysis and 20 soil samples was used for model validation. The regression analysis showed a linear relationship between D SWRC , with clay, silt contents and soil bulk density with the goodness of fit, R 2 = 0.909, but lime content did not show any significant effect on SWRC prediction improvement. Therefore, it can be concluded that estimating SWRC in calcareous soil using D SWRC obtained from soil easily measured properties will be a good, rapid and reliable alternative for reliable estimation of soil hydraulic properties of these areas. Keywords: Fractal model; lime percent; Regression analysis; Soil water retention curve

Highlights

Exponent of soil water retention curve, dimension of SWRC (DSWRC) is physically meaningful, its direct measurement is difficult in laboratory and field soil water retention experiments are laborious and time consuming
The measured DSWRC for 110 soil samples used for regression analysis and 20 soil samples was used for model validation
The regression analysis showed a linear relationship between DSWRC, with clay, silt contents and soil bulk density with the goodness of fit, R2 = 0.909, but lime content did not show any significant effect on SWRC prediction improvement

Summary

Introduction

Exponent of soil water retention curve, DSWRC is physically meaningful, its direct measurement is difficult in laboratory and field soil water retention experiments are laborious and time consuming. Estimation of DSWRC based on the available data, can be very useful alternative. Soil particle size distribution has fractal properties. Fractal model can be used to estimate the soil water retention curve. The main objectives of this study were (1) determining the DSWRC from SWRC experimental data, (2) establishing a relationship among DSWRC, and soil readily available characteristics (i.e. clay, silt and sand contents, lime percent and bulk density), (3) validating the developed relationship in SWRC estimation in calcareous soil

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