Crustal Groundwater Volumes Greater Than Previously Thought

Grant Ferguson, Jennifer C. McIntosh, Oliver Warr, Barbara Sherwood Lollar, Christopher J. Ballentine, James S. Famiglietti, Ji Hyun Kim, Joseph R. Michalski, John F. Mustard, Jesse Tarnas, Jeffrey J. McDonnell

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Global groundwater volumes in the upper 2 km of the Earth's continental crust—critical for water security—are well estimated. Beyond these depths, a vast body of largely saline and non-potable groundwater exists down to at least 10 km—a volume that has not yet been quantified reliably at the global scale. Here, we estimate the amount of groundwater present in the upper 10 km of the Earth's continental crust by examining the distribution of sedimentary and crystalline rocks with depth and applying porosity-depth relationships. We demonstrate that groundwater in the 2–10 km zone (what we call “deep groundwater”) has a volume comparable to that of groundwater in the upper 2 km of the Earth's crust. These new estimates make groundwater the largest continental reservoir of water, ahead of ice sheets, provide a basis to quantify geochemical cycles, and constrain the potential for large-scale isolation of waste fluids.

Original languageEnglish (US)
Article numbere2021GL093549
JournalGeophysical Research Letters
Volume48
Issue number16
DOIs
StatePublished - Aug 28 2021

Keywords

  • cratons
  • deep groundwater
  • global hydrology
  • porosity
  • sedimentary basins

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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