Estimating hydraulic parameters of stony soils on the basis of one-dimensional water absorption properties

Abstract

Rock fragment content and grain size affect the structure of soil and movement properties of soil water. In this paper, influences of rock fragment content and grain size on infiltration characteristics and hydraulic parameters of stony-soil media were analysed on the basis of one-dimensional horizontal absorption experiments. Two methods for estimating diffusivity of stony soils, using cumulative infiltration, wetting front and soil water content distribution, respectively, were compared to evaluate their applicability. Also, estimating method of Brooks–Corey water retention curve for stony soils, using cumulative infiltration and wetting front, was evaluated based on the measured retention curve. The results showed that both rock fragment content and grain size had significant effects on infiltration properties and hydraulic parameters of stony-soil media. Both cumulative infiltration and wetting front distance of stony-soil media were smaller than those of fine soil since rock fragment hindered infiltration. The more rock fragment content, the slower soil water moved, but the turning point appeared at the rock fragment content of 40%. Besides, larger rock fragment grain size accelerated infiltration at certain content. Both rock fragment content and grain size had significant influences on hydraulic parameters, and there were linear relationships between parameters and rock fragment content. Two kinds of methods for estimating diffusivity of stony soils had a very good consistency for some experimental scenarios. Besides, cumulative infiltration and wetting front could be used to accurately estimate water retention curve of stony soils.