Factors affecting the variation of permeability with depth in carbonate aquifers

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Publication Date

10-9-2020

Publication Title

Hydrogeology Journal

Volume Number

29

Abstract

The permeability of carbonate aquifers varies widely, but the major factors that influence changes in permeability with depth are not well established. Trends in permeability and solute concentration data were analysed for four carbonate aquifers where data were available over a wide range of depths. The Deep Geologic Repository (Ontario, Canada), Edwards Aquifer (Texas, USA), and Chalk aquifer (England, UK) all had permeability data from wells, supplemented by numerical groundwater flow models. There were no permeability data from wells for the fourth site, the Arabika Massif in the Caucasus Mountains (Abkhazia, Georgia). However, the permeability could be calculated from the water-table gradient. It was found that high permeabilities are associated with low solute concentrations, but there is a weak correlation between permeability and depth. The highest permeabilities are found in the freshwater zone, where total dissolved solids (TDS) concentrations are <1,000 mg/L. The presence of aquitards which limit vertical flow were the prime factor in determining the depth of the freshwater zone. This depth varied from 40 m at the Ontario site to >2,000 m below the surface in the Caucasus Mountains. This study highlights the importance of dissolution, the link between permeability and both solute concentrations and flow rate, and how aquitards can play a pivotal role in how permeability varies as a function of depth.

Keywords

Aquifers, Carbonate rocks, Hydrogeology, Permeability, Groundwater flow

Document Type

Article

Digital Object Identifier (DOI)

https://doi.org/10.1007/s10040-020-02247-2

Language

English; French; Spanish; Chinese; Portuguese

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