Validation of the Arya and Paris Water Retention Model for Brazilian Soils

Abstract

The Arya and Paris (AP) model predicts soil water retention curves from soil particle‐size distribution (PSD) data based on the similarity between these two functions. The AP model estimates pore radius (ri) from the radius (Ri) of spherical particles by scaling pore length with a parameter α. This paper evaluates the performance of the AP model with representative Brazilian soil types using three constant α values: α = 1.38, 0.938 (literature values), and 0.977, (obtained in the present work); and a α‐variable approach, where α is determined as a function of soil water content (θ). The study was performed with 104 soil samples collected in three sites. The soil PSD curves were obtained with an automatic soil particle analyzer based on the attenuation of γ‐ray by dispersed soil particles falling in a liquid medium and the soil water retention were measured with tension table and Richard chamber methods. The best mathematical representation of the α = f(θ) relationship was obtained with a first‐order exponential decay equation [α = 0.947 + 0.427exp(−θ/0.129)] that provided values of α in the range from 1.37 (θ = 0 m3 m−3) to 0.96 (θ = 0.6 m3 m−3). The root mean square deviation values of estimated and measured θ were 0.062 m3 m−3 for α = f(θ), 0.073 m3 m−3 for α = 0.977, 0.080 m3 m−3 for α = 0.938, and 0.136 m3 m−3 for α = 1.38. Therefore, for these set of soils the α‐variable approach and the constant ones using 0.977 and 0.938 presented the best estimation for the soil water retention relationships.

Predicting available water of soil from particle-size distribution and bulk density in an oasis–desert transect in northwestern China

“…In this semi-physical approach, pore radii were determined by scaling the pore lengths of cubic close-packed assemblages with spherical particles to those of the natural structure. Researchers thereafter have suggested that the SWCC prediction by the AP model would improve if the scaling parameter (a) were formulated as a varying rather than a constant value over soil particle ranges and textural classes (Basile and D'Urso, 1997;Arya et al, 1999;Vaz et al, 2005). The AP model has been progressively modified and used to predict SWCC.…”

“…(3) is the scaling parameter. Basile and D'Urso (1997) and Vaz et al (2005) expressed a values as functions of h and h, respectively. To decrease the uncertainty in the SWCC prediction caused by the interdependence of a on h or h, we adopted the formulation proposed by Arya et al (1999), that is,…”

Evaluating the Scale Factors of Pedo-Transfer Modeling the Soil Water Characteristic Curve of Zakho Soils

“…Another method suggested by the same researcher and also adopted by (S. Liu, et al, 2013) for the estimation of is to linear fit between and as follows: (12) The constant values of the scale factor obtained by constant method and the linear parameter and, ( that obtained by the above methods are shown in Table (2). (Vaz et al 2005), appraise the performance of the AP model by employing an expression for as a function of the soil volumetric water content, (θ); as (13) The aforementioned scaling methods have been utilized in association with the Arya and Paris algorithm for estimation the soil water characteristic curve relationships for the soil specimens of Zakho city.…”

Prediction of Soil Water Characteristic Curve Using Physically Based Scaling Technique

“…The AP procedure introduced an empirical parameter, α, used to scale pore attributes from hypothetical formations to natural structures. Arya and Paris (1981) initially determined α as constant, whereas several researchers have suggested that variable α would improve the predictions of the SWCC (Basile and D'Urso, 1997;Arya et al, 1999;Vaz et al, 2005). Fractal concepts have also been used to derive α (Tyler and Wheatcraft, 1989).…”