An evaluation of air permeability measurements to characterize the saturated hydraulic conductivity of soil reclamation covers

Abstract

, S. L. 2015. An evaluation of air permeability measurements to characterize the saturated hydraulic conductivity of soil reclamation covers. Can. J. Soil Sci. 95: 15Á26. The saturated hydraulic conductivity (K s ) of soil covers used in land reclamation is known to change over time as the result of weathering processes. Guelph permeameter (GP) measurements have been used to track the evolution of K s for soil covers at an oil sands mine near Ft. McMurray, Alberta. Although successful, the method was time consuming and consequently a rapid method of estimating K s based on in situ air permeability measurements was developed. The objectives of this study were: (1) to use air permeability measurements to characterize the spatial variations of K s for typical reclamation soils and (2) to compare air permeability measurements to direct measurements obtained through laboratory and GP measurements. The results highlight that the values of K s estimated from measured air permeability values were higher than the values of K s measured directly using the GP. This is likely due to swelling of clay soils or air-entrapment during GP measurements. Although the magnitude was over-estimated, the variability of K s was captured by the air permeability measurements. Consequently, a limited program of comparative GP and air permeameter measurements could be used to more rapidly characterize the K s of reclamation covers over time.

High variability of soil erosion and hydrological processes in Mediterranean hillslope vineyards (Montes de Málaga, Spain)

“…A large number of instruments and methods are available to measure the infiltration, the permeability and Kf s (Archer et al, 2013;Bagarello et al, 2014;Cerdà, 1997;Gupta et al, 2006Gupta et al, , 1993Gwenzi et al, 2011;Huang et al, 2016Huang et al, , 2014Jačka et al, 2014;Kodešová et al, 2010;MacDonald et al, 2012;Peter and Ries, 2013;Wu et al, 1992). In this research, a Guelph permeameter (GP) was applied.…”

Comparing the Physical Quality of Polish Chernozems Classified in Various Complexes of Agricultural Suitability

“…Gas exchange between the soil and the atmosphere takes place primarily under the effect of concentration gradient (diffusive flow) and, to a lesser extent, under the effect of pressure gradient [52]. Like hydraulic conductivity, air permeability at the state of field water capacity depends primarily on the volume of soil macropores with diameter >20 μm, and especially on the length, form, and continuity of biogenic channels [53][54][55]. Air permeability value accepted as favourable for gas exchange is 35 ·s -1 as high.…”

Characterizing the spatial variability of the hydraulic conductivity of reclamation soils using air permeability

“…This can include changes in the water chemistry during GP testing which can lead to particle dispersion or changes in soil structure (Quirk, 1986). The flow of air may not represent the viscous, laminar flow of water due to slippage along solid boundaries or the development of turbulent flow, and in the case of water flow, there may be entrapped air within the soil which blocks water movement through all of the pores (Iversen et al, 2003;Huang et al, 2015b). Despite these problems, the k a measured at or near field capacity has been shown to provide a useful estimate of K s , since the air flow (in a dry soil) and water flow (in a saturated soil) are dominated by the pore distribution and structure associated with the largest pore sizes (Watson and Luxmoore, 1986;Kelln et al, 2009).…”

“…The value of K s can be estimated from field measurements of air conductivity (K a , m s −1 ) using the following equations as shown by Loll et al (1999), Iversen et al (2001), Wells et al (2006), Chief et al (2008), Rodger and Barbour (2008), Huang et al (2015b) and others: k a is equal to k w ) if the media is considered to be inert and the testing is done at identical fluid contents of the respective phases (Wells et al, 2007). However; in practice, there are factors that may result in different values for the intrinsic permeability as measured by air and water.…”