44
IRUS Total
Downloads
  Altmetric

Remote detection of saline intrusion in a coastal aquifer using borehole measurements of self potential

File Description SizeFormat 
MacAllister_et_al-2017-Water_Resources_Research.pdfPublished version1.72 MBAdobe PDFView/Open
MacAllisteretal_WRR_2018_SalineIntrusion_SP_Data.zipSupporting information122.37 MBUnknownView/Open
Title: Remote detection of saline intrusion in a coastal aquifer using borehole measurements of self potential
Authors: MacAllister, DJ
Jackson, MD
Butler, AP
Vinogradov, J
Item Type: Journal Article
Abstract: Two years of self‐potential (SP) measurements were made in a monitoring borehole in the coastal UK Chalk aquifer. The borehole SP data showed a persistent gradient with depth, and temporal variations with a tidal power spectrum consistent with ocean tides. No gradient with depth was observed at a second coastal monitoring borehole ca. 1 km further inland, and no gradient or tidal power spectrum were observed at an inland site ca. 80 km from the coast. Numerical modeling suggests that the SP gradient recorded in the coastal monitoring borehole is dominated by the exclusion‐diffusion potential, which arises from the concentration gradient across a saline front in close proximity to, but not intersecting, the base of the borehole. No such saline front is present at the two other monitoring sites. Modeling further suggests that the ocean tidal SP response in the borehole, measured prior to breakthrough of saline water, is dominated by the exclusion‐diffusion potential across the saline front, and that the SP fluctuations are due to the tidal movement of the remote front. The electrokinetic potential, caused by changes in hydraulic head across the tide, is one order of magnitude too small to explain the observed SP data. The results suggest that in coastal aquifers, the exclusion‐diffusion potential plays a dominant role in borehole SP when a saline front is nearby. The SP gradient with depth indicates the close proximity of the saline front to the borehole and changes in SP at the borehole reflect changes in the location of the saline front. Thus, SP monitoring can be used to facilitate more proactive management of abstraction and saline intrusion in coastal aquifers.
Issue Date: 10-Mar-2018
Date of Acceptance: 14-Feb-2018
URI: http://hdl.handle.net/10044/1/56766
DOI: 10.1002/2017WR021034
ISSN: 0043-1397
Publisher: American Geophysical Union
Start Page: 1669
End Page: 1687
Journal / Book Title: Water Resources Research
Volume: 54
Issue: 3
Copyright Statement: © 2018 The Authors. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made (https://creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords: Science & Technology
Life Sciences & Biomedicine
Physical Sciences
Environmental Sciences
Limnology
Water Resources
Environmental Sciences & Ecology
Marine & Freshwater Biology
self-potential
seawater Intrusion
coastal aquifers
exclusion-diffusion potential
electrokinetic potential
hydrogeophysics
ELECTRICAL-RESISTIVITY TOMOGRAPHY
HYDRAULICALLY ACTIVE FRACTURES
HYDROCARBON RESERVOIRS
CONTAMINANT TRANSPORT
CARBONATE AQUIFERS
SOUTHERN ENGLAND
JOINT INVERSION
CHALK AQUIFER
POROUS-MEDIA
TRACER TEST
Environmental Engineering
0406 Physical Geography and Environmental Geoscience
0905 Civil Engineering
0907 Environmental Engineering
Publication Status: Published
Online Publication Date: 2018-02-16
Appears in Collections:Civil and Environmental Engineering
Earth Science and Engineering
Faculty of Engineering