A modification of the constant-head permeameter to measure saturated hydraulic conductivity of highly permeable media

Jelmer J Nijp; Klaas Metselaar; Juul Limpens; Harm P A Gooren; Sjoerd E A T M van der Zee

doi:10.1016/j.mex.2017.02.002

A modification of the constant-head permeameter to measure saturated hydraulic conductivity of highly permeable media

MethodsX. 2017 Feb 14:4:134-142. doi: 10.1016/j.mex.2017.02.002. eCollection 2017.

Authors

Jelmer J Nijp¹, Klaas Metselaar², Juul Limpens³, Harm P A Gooren², Sjoerd E A T M van der Zee⁴

Affiliations

¹ Wageningen University, Soil Physics and Land Management Group, Wageningen, The Netherlands; Wageningen University, Plant Ecology and Nature Conservation Group, Wageningen, The Netherlands; Wageningen University, Soil Geography and Landscape Group, Wageningen, The Netherlands.
² Wageningen University, Soil Physics and Land Management Group, Wageningen, The Netherlands.
³ Wageningen University, Plant Ecology and Nature Conservation Group, Wageningen, The Netherlands.
⁴ Wageningen University, Soil Physics and Land Management Group, Wageningen, The Netherlands; Monash University, School of Chemistry, Melbourne, Victoria 3800, Australia.

Abstract

The saturated hydraulic conductivity (K_s ) is a key characteristic of porous media, describing the rate of water flow through saturated porous media. It is an indispensable parameter in a broad range of simulation models that quantify saturated and/or unsaturated water flow. The constant-head permeameter test is a common laboratory method to determine K_s on undisturbed soil samples collected from the field. In this paper we show that the application of this conventional method may result in a biased K_s in the case of highly permeable media, such as the top layer of Sphagnum peat and gravel. Tubes in the conventional permeameter, that collect water under the sample, introduce a hydraulic head-dependent resistance for highly permeable media and result in an underestimation of K_s . We present a simple and low-budget alternative of the constant-head permeameter test that overcomes the disadvantages of conventional permeameters. The new method was successfully tested on intact highly permeable peatmoss collected from a northern peatland. •Conventional constant-head permeameters underestimate K_s of highly permeable media due to flow resistance in tubing systems•We developed the low-resistance permeameter to overcome this disadvantage.•Testing of the low-resistance permeameter demonstrated no systematic bias and successful application for highly permeable media.

Keywords: Compression; Laboratory method; Low-resistance permeameter; Peat; Permeability; Reynolds number; Soil physics; Sphagnum.