Identifying recharge under subtle ephemeral features in flat-lying semi-arid region using a combined geophysical approach

Brady A. Flinchum, Eddie Banks, Michael Hatch, Okke Batelaan, Luk Peeters, Sylvain Pasquet

Research output: Contribution to journalArticle

Abstract

Identifying and quantifying recharge processes linked to ephemeral surface water features is challenging due to their episodic nature. We use a unique combination of well-established near-surface geophysical methods to provide evidence of a surface and groundwater connection under a small ephemeral recharge feature in a flat, semi-arid region near Adelaide, Australia. We use a seismic survey to obtain P-wave velocity through travel-time tomography and S-wave velocity through the multichannel analysis of surface waves. The ratios between P-wave and S-wave velocities allow us to infer the position of the water table. A separate survey was used to obtain electrical conductivity measurements from time-domain electromagnetics and water contents were acquired by downhole nuclear magnetic resonance. The combined geophysical observations provide evidence to support a groundwater mound underneath a subtle ephemeral feature. Our results suggest that recharge is localized and that small-scale ephemeral features play an important role in groundwater recharge. Furthermore, we show that a combined geophysical approach can provide a unique perspective that helps shape the hydrogeological conceptualization of a semi-arid region.
Original languageEnglish
Pages (from-to)1-31
Number of pages31
JournalHydrology and Earth System Sciences
DOIs
Publication statusE-pub ahead of print - 2 Jun 2020

Bibliographical note

© Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.

Keywords

  • recharge
  • ephemeral
  • semi-arid region
  • geophysical
  • P-wave
  • S-wave

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