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Quantifying compressible groundwater storage by combining cross-hole seismic surveys and head response to atmospheric tides

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Version 2 2024-06-05, 00:59
Version 1 2018-11-05, 13:58
journal contribution
posted on 2024-06-05, 00:59 authored by GC Rau, RI Acworth, LJS Halloran, Wendy TimmsWendy Timms, MO Cuthbert
Groundwater specific storage varies by orders of magnitude, is difficult to quantify, and prone to significant uncertainty. Estimating specific storage using aquifer testing is hampered by the nonuniqueness in the inversion of head data and the assumptions of the underlying conceptual model. We revisit confined poroelastic theory and reveal that the uniaxial specific storage can be calculated mainly from undrained poroelastic properties, namely, uniaxial bulk modulus, loading efficiency, and the Biot-Willis coefficient. In addition, literature estimates of the solid grain compressibility enables quantification of subsurface poroelastic parameters using field techniques such as cross-hole seismic surveys and loading efficiency from the groundwater responses to atmospheric tides. We quantify and compare specific storage depth profiles for two field sites, one with deep aeolian sands and another with smectitic clays. Our new results require bulk density and agree well when compared to previous approaches that rely on porosity estimates. While water in clays responds to stress, detailed sediment characterization from a core illustrates that the majority of water is adsorbed onto minerals leaving only a small fraction free to drain. This, in conjunction with a thorough analysis using our new method, demonstrates that specific storage has a physical upper limit of (Formula presented.) m−1. Consequently, if larger values are derived using aquifer hydraulic testing, then the conceptual model that has been used needs reappraisal. Our method can be used to improve confined groundwater storage estimates and refine the conceptual models used to interpret hydraulic aquifer tests.

History

Journal

Journal of geophysical research: earth surface

Volume

123

Pagination

1910-1930

Location

Washington, D.C.

Open access

  • Yes

ISSN

2169-9003

eISSN

2169-9011

Language

eng

Publication classification

C Journal article, C1.1 Refereed article in a scholarly journal

Copyright notice

2018, American Geophysical Union

Issue

8

Publisher

American Geophysical Union