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Lookup NU author(s): Dr Sarah Clancy, Professor Richard DaviesORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2020 The Authors. Hydrological Processes published by John Wiley & Sons Ltd. An environmental concern with hydraulic fracturing for shale gas is the risk of groundwater and surface water contamination. Assessing this risk partly involves the identification and understanding of groundwater–surface water interactions because potentially contaminating fluids could move from one water body to the other along hydraulic pathways. In this study, we use water quality data from a prospective shale gas basin to determine: if surface water sampling could identify groundwater compartmentalisation by low-permeability faults; and if surface waters interact with groundwater in underlying bedrock formations, thereby indicating hydraulic pathways. Variance analysis showed that bedrock geology was a significant factor influencing surface water quality, indicating regional-scale groundwater–surface water interactions despite the presence of an overlying region-wide layer of superficial deposits averaging 30–40 m thickness. We propose that surface waters interact with a weathered bedrock layer through the complex distribution of glaciofluvial sands and gravels. Principal component analysis showed that surface water compositions were constrained within groundwater end-member compositions. Surface water quality data showed no relationship with groundwater compartmentalisation known to be caused by a major basin fault. Therefore, there was no chemical evidence to suggest that deeper groundwater in this particular area of the prospective basin was reaching the surface in response to compartmentalisation. Consequently, in this case compartmentalisation does not appear to increase the risk of fracking-related contaminants reaching surface waters, although this may differ under different hydrogeological scenarios.
Author(s): Wilson MP, Worrall F, Clancy SA, Ottley CJ, Hart A, Davies RJ
Publication type: Article
Publication status: Published
Journal: Hydrological Processes
Year: 2020
Volume: 34
Issue: 15
Pages: 3271-3294
Print publication date: 15/07/2020
Online publication date: 27/05/2020
Acceptance date: 25/04/2020
Date deposited: 15/06/2020
ISSN (print): 0885-6087
ISSN (electronic): 1099-1085
Publisher: John Wiley and Sons Ltd
URL: https://doi.org/10.1002/hyp.13795
DOI: 10.1002/hyp.13795
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