Understanding the Geodetic Signature of Large Aquifer Systems: Example of the Ozark Plateaus in Central United States

Stacy Larochelle, Kristel Chanard, Luce Fleitout, Jérôme Fortin, Adriano Gualandi, Laurent Longuevergne, Paul Rebischung, Sophie Violette, Jean Philippe Avouac

Research output: Contribution to journalArticlepeer-review

Abstract

The continuous redistribution of water involved in the hydrologic cycle leads to deformation of the solid Earth. On a global scale, this deformation is well explained by the loading imposed by hydrological mass variations and can be quantified to first order with space-based gravimetric and geodetic measurements. At the regional scale, however, aquifer systems also undergo poroelastic deformation in response to groundwater fluctuations. Disentangling these related but distinct 3D deformation fields from geodetic time series is essential to accurately invert for changes in continental water mass, to understand the mechanical response of aquifers to internal pressure changes as well as to correct time series for these known effects. Here, we demonstrate a methodology to accomplish this task by considering the example of the well-instrumented Ozark Plateaus Aquifer System (OPAS) in the central United States. We begin by characterizing the most important sources of groundwater level variations in the spatially heterogeneous piezometer dataset using an Independent Component Analysis. Then, to estimate the associated poroelastic displacements, we project geodetic time series corrected for hydrological loading effects onto the dominant groundwater temporal functions. We interpret the extracted displacements in light of analytical solutions and a 2D model relating groundwater level variations to surface displacements. In particular, the relatively low estimates of elastic moduli inferred from the poroelastic displacements and groundwater fluctuations may be indicative of aquifer layers with a high fracture density. Our findings suggest that OPAS undergoes significant poroelastic deformation, including highly heterogeneous horizontal poroelastic displacements.

Original languageEnglish
Article numbere2021JB023097
JournalJournal of Geophysical Research: Solid Earth
Volume127
Issue number3
Early online date15 Feb 2022
DOIs
Publication statusPublished - 1 Mar 2022

Bibliographical note

Funding Information:
This study was supported by the National Sciences and Engineering Research Council of Canada through a postgraduate doctoral scholarship (PGSD-3-517,078-2018), the Office for Science and Technology of the Embassy of France in the United States through a STEM Chateaubriand Fellowship, the Institut de Physique du Globe de Paris (IPGP contribution #4232) as well as the King Abdullah City for Science and Technology (KACST). The authors would like to thank the editor, Paul Tregoning, and two anonymous reviewers for their constructive comments which have led to an improved manuscript as well as Roland B?rgmann for insightful discussions. SL would also like to thank Katherine Knierim for providing helpful resources to map OPAS as well as Wilbur Shirley for help with the Fourier analysis.


Publisher Copyright:
© 2022. American Geophysical Union. All Rights Reserved.

Keywords

  • Elastic properties
  • GNSS and GRACE data
  • Hydrogeodesy
  • Hydrogeology
  • Hydrological loading
  • Poroelasticity

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