Hydraulic Conductivity Determinations in Unlithified Glacial and Fluvial Materials

Abstract

Experiences with many measurements of the hydraulic conductivity of unlithified glacial and fluvial materials in Wisconsin suggest that hydraulic conductivity must be viewed in terms of the operational scale of measurement, based on the scale of the problem at hand and the volume of the materials of interest. Frequently, the hydraulic conductivity of a given lithostratigraphic unit appears to increase as the operational scale of measurement increases. In particular, laboratory methods can yield hydraulic conductivities one to two orders of magnitude lower than conductivities determined in field tests on the same materials. The operational scale of most laboratory methods is much smaller than the operational scale of most field problems, and laboratory tests, although often logistically and financially attractive, may be of little value in characterizing the hydraulic conductivity of Pleistocene and recent deposits at working field scales.

Field-scale spatial variability of saturated hydraulic conductivity on a recently constructed artificial ecosystem

“…Previous studies have also shown that K s increases as the scale of measurement or sampling volume increases particularly for structured soils with macroporosity (e.g. Bagarello, 1997;Bradbury and Muldoon, 1990). Therefore, small sample volumes may fail to account for K s arising from macropore or preferential flow (Mallants et al, 1997).…”

Hydrogeological implications of glacial landscape evolution at Skeiðarársandur, SE Iceland

“…Although there are problems applying a single equation to sediments from a naturally heterogeneous environment (Bradbury and Muldoon, 1990), the Hazen formula has been shown to produce less variable results than some other methods derived from sandy substrates (Goodman, 1999) and has been used previously in studies of glaciofluvial deposits (e.g. Anderson et al, 1999).…”

Thermal plume transport from sand and gravel pits – Potential thermal impacts on cool water streams

“…For example, Bradbury and Muldoon (1990) and Rehfeldt et al (1992) reported differences of one-to two-orders of magnitude, and Wolf et al (1991) and Rovey and Niemann (2001) reported differences of one-order of magnitude. These differences result, in part, from the volume of aquifer influenced during the test and how the heterogeneities encountered within this volume are spatially averaged by the test (e.g., Desbarats, 1994;Sánchez-Vila et al, 1996;Rovey and Niemann, 2001;Beckie and Harvey, 2002;Molz et al, 2005).…”

“…These differences result, in part, from the volume of aquifer influenced during the test and how the heterogeneities encountered within this volume are spatially averaged by the test (e.g., Desbarats, 1994;Sánchez-Vila et al, 1996;Rovey and Niemann, 2001;Beckie and Harvey, 2002;Molz et al, 2005). To investigate the dependency of our measured hydraulic conductivities on the measurement scale, we chose the test volume as a measure of scale (Bradbury and Muldoon, 1990;SchulzeMakush et al, 1999 Methods that are more rigorous for estimating support volumes for pumping and slug tests have been developed for specific flow conditions (e.g., Desbarats, 1994;Beckie, 2001;Beckie and Harvey, 2002;Molz et al, 2005). However, applying these methods to the test conditions present at our site is outside of the scope of this research.…”