New Equations for the Determination of Soil Saturated Hydraulic Conductivity Using the Van Genuchten Model Parameters and Effective Porosity

Abstract

Modifications of the Kozeny-Carman approach (Ks=AΦB) for the determination of saturated hydraulic conductivity Ks using the van Genuchten model parameters and the effective porosity Φe are presented in this study. Two models {a two-parametric Ks(a, Φe) and a three-parametric Ks(a, Si, Φe)} were developed for Ks determination. In the two-parametric model the power constant was replaced by the f factor (f=aΦe). The factor f includes the parameter a of the van Genuchten model, in order to describe its effect on the part of the pore size distribution which participates in the effective porosity Φe. The three-parametric model was improved by inclusion of the water retention curve slope Si at the inflection point. The models were calibrated and validated using two published data sets which cover the 12 USDA soil texture classes. The proposed models were also compared with other published models of Ks, which are based on the van Genuchten parameters and the Kozeny-Carman approach. The results indicated an adequate predictive accuracy of the models through a calibration and validation procedure using data sets from different sources and better performance compared to other models, setting a new approach for the indirect determination of Ks using only data from the water retention curve

Pesticide leaching through sandy and loamy fields – Long-term lessons learnt from the Danish Pesticide Leaching Assessment Programme

“…It is well documented (Aschonitis and Antonopoulos, 2013) that the effective porosity in loamy soil corresponding to connected discontinuities, such as wormholes and fractures, is low compared to that of sandy soil, with the result that climatic conditions have a greater impact on the pore system. The consequences are: (i) immediate response to a precipitation or snowmelt event causing rapid flow and transport through discontinuities (Rosenbom et al, 2008(Rosenbom et al, , 2009bVryzas et al, 2012), which may sometimes be directly connected to drains (Nielsen, 2010); and (ii) seasonal fluctuations of up to 4 m in the groundwater table with resultant drainage, primarily in periods when the groundwater table is located above the drains (above 1.1e1.2 m b.g.s.).…”

An Integrated Approach to Assessing the Soil Quality and Nutritional Status of Large and Long-Term Cultivated Rice Agro-Ecosystems

“…An additional threshold related to soil texture can be developed considering sand. Taking into account the hydraulic properties of the 12 USDA soil texture classes according to the two extensive datasets of Carsel and Parrish [54] and Schaap et al [55], the saturated hydraulic conductivity K s shows a steep increase in the Sandy Loam (SL), Loamy Sand (LS), and Sand (S) classes (more than double K s compared to the other classes; see the complete tables of the two datasets in Aschonitis and Antonopoulos [56]). These three classes correspond to sand% values above 50%.…”

An Alert Regarding a Common Misinterpretation of the Van Genuchten α Parameter

“…Some use this kind of identification when describing VG parameters (Souza et al, 2008a;Lima et al, 2014;Oliveira Júnior et al, 2014), others when explicitly interpreting results of α values to the air-entry pressure (Souza et al, 2008b;Silva et al, 2009;Mota et al, 2017). In international literature, a similar description can sometimes be found (Pollaco and Mohanty, 2012;Aschonitis and Antonopoulos, 2013;Aschonitis et al, 2015;Dokoohaki et al, 2017).…”