The usefulness of outcrop analogue air permeameter measurements for analyzing aquifer heterogeneity: quantifying outcrop hydraulic conductivity and its spatial variability. Issue 20 (2nd September 2013)

• Record Type: Journal Article
• Authors: Rogiers, Bart; Beerten, Koen; Smeekens, Tuur; Mallants, Dirk; Gedeon, Matej; Huysmans, Marijke; Batelaan, Okke; Dassargues, Alain
• Is Part Of: Hydrological processes. Volume 28:Issue 20(2014:Mar.)
• Page Start: 5176
• Page End: 5188
• Publication Date: 2013-09-02
• Subjects: Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.10007
• Languages: English
• ISSNs: 0885-6087

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Saturated hydraulic conductivity (<italic>K</italic>) is one of the most important parameters determining groundwater flow and contaminant transport in both unsaturated and saturated porous media. Although several well‐established laboratory methods exist for determining <italic>K</italic>, <italic>in situ</italic> measurements of this parameter remain very complex and scale dependent. Often, the limited accessibility of subsurface sediments for sampling means an additional impediment to our ability to quantify subsurface <italic>K</italic> heterogeneity. One potential solution is the use of outcrops as analogues for subsurface sediments.</p> <p>This paper investigates the use of air permeameter measurements on outcrops of unconsolidated sediments to quantify <italic>K</italic> and its spatial heterogeneity on a broad range of sediment types. The Neogene aquifer in northern Belgium is used as a case study for this purpose. To characterize the variability in <italic>K</italic>, 511 small‐scale air permeability measurements were performed on outcrop sediments representative over five of the aquifer's lithostratigraphic units. From these measurements, outcrop‐scale equivalent <italic>K</italic> tensors were calculated using numerical upscaling techniques. Validation of the air permeameter‐based <italic>K</italic> values by comparison with laboratory constant head <italic>K</italic> measurements reveals a correlation of 0.93. Overall, the results indicate that hand‐held air permeameters are very efficient and accurate tools to characterize saturated <italic>K</italic>, as well as its small‐scale variability and anisotropy on a broad range of unconsolidated sediments. The studied outcrops further provided a qualitative understanding of aquifer hydrostratigraphy and quantitative estimates about <italic>K</italic> variability at the centimetre‐scale to metre‐scale. Copyright © 2013 John Wiley & Sons, Ltd.</p> </abstract>