Influence of transient porosity in a coupled fracture-skin-matrix system at the scale of a single fracture

Berlin, M.; Natarajan, N.; Vasudevan, Mukund; Kumar, G. Suresh

doi:10.1007/s11356-020-11489-2

Cited by 6 publications

(1 citation statement)

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“…These contaminants include nitrate, sulphate, chloride, toxic organic compounds released by mineral fertilizers and pesticides, and pathogens (Tratner et al 1997;Drew 2008;Reimann and Hill 2009;Göppert and Goldscheider 2011;Gregory et al 2014;Reh et al 2014;Palmucci et al 2016;Liu et al 2019;Medici et al 2019cMedici et al , 2020Rusi et al 2018;Ducci et al 2019;Parker et al 2019;Ren et al 2019). Fast transport of such pollutants typically occurs through bedding plane discontinuities, joints, and fault-related fractures rather than via porous matrix in lithified carbonate rocks (Berkowitz 2002;West and Odling 2007;Medici et al 2016, Jones et al 2017Maldaner et al 2018;Berlin et al 2020;Hu et al 2020). This category of fractured aquifers is particularly prone to solutional widening of rock discontinuities and are hence the most vulnerable because contaminant plumes are transported at relatively high rates.…”

Section: Introductionmentioning

confidence: 99%

Groundwater flow velocities in karst aquifers; importance of spatial observation scale and hydraulic testing for contaminant transport prediction

Medici

West

2021

Environ Sci Pollut Res

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We review scale dependence of hydraulic conductivities and effective porosities for prediction of contaminant transport in four UK karst aquifers. Approaches for obtaining hydraulic parameters include core plug, slug, pumping and pulse tests, calibration of groundwater flow models, and spring recession curves. Core-plug and slug tests are unsuitable because they do not characterise a large enough volume to include a representative fracture network.Pumping test values match regional-scale hydraulic conductivities from flow modelling for the less intensively karstified aquifers: Magnesian Limestone, Jurassic Limestone and Cretaceous Chalks. Reliable bulk hydraulic conductivities were not available for the intensively-karstified Carboniferous Limestone due to dominance of flow through pipe-conduits in the Mendips. Here, the only hydraulic conductivity value found from springs recession is one order of magnitude higher than that indicated by pumping tests. For all four carbonate aquifers, effective porosities assumed for transport modelling are two orders of magnitude higher than those found from tracer and hydrogeophysical tests. A combination of low hydraulic conductivities and assumed flowing porosities, has resulted in underestimated flow velocities. The UK karst aquifers are characterized by a range of hydraulic behaviours that fit those of karst aquifers worldwide. Indeed, underestimation of flow velocity due to inappropriate parameter selection is common to intensively karstified aquifers of southern France, north-western Germany and Italy. Similar issues arise for the Canadian Silurian carbonates where high effective porosities (e.g., 5%) used in transport models leads to underestimation of groundwater velocities. We recommend values in the range of 1% -0.01% for such aquifers.

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