The Demographics of Water: A Review of Water Ages in the Critical Zone

Research output: Contribution to journalReview articleContributedpeer-review

Contributors

  • Matthias Sprenger - , University of Freiburg, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), North Carolina State University (Author)
  • Christine Stumpp - , University of Natural Resources and Life Sciences, Vienna (Author)
  • Markus Weiler - , University of Freiburg (Author)
  • Werner Aeschbach - , Heidelberg University  (Author)
  • Scott T. Allen - , ETH Zurich (Author)
  • Paolo Benettin - , Swiss Federal Institute of Technology Lausanne (EPFL) (Author)
  • Maren Dubbert - , University of Freiburg (Author)
  • Andreas Hartmann - , University of Freiburg, University of Bristol (Author)
  • Markus Hrachowitz - , Delft University of Technology (Author)
  • James W. Kirchner - , ETH Zurich, Swiss Federal Institute for Forest, Snow and Landscape Research (Author)
  • Jeffrey J. McDonnell - , University of Saskatchewan, Ludong University, University of Birmingham (Author)
  • Natalie Orlowski - , University of Freiburg (Author)
  • Daniele Penna - , University of Florence (Author)
  • Stephan Pfahl - , Free University of Berlin (Author)
  • Michael Rinderer - , University of Freiburg (Author)
  • Nicolas Rodriguez - , Luxembourg Institute of Science and Technology (Author)
  • Maximilian Schmidt - , Heidelberg University  (Author)
  • Christiane Werner - , University of Freiburg (Author)

Abstract

The time that water takes to travel through the terrestrial hydrological cycle and the critical zone is of great interest in Earth system sciences with broad implications for water quality and quantity. Most water age studies to date have focused on individual compartments (or subdisciplines) of the hydrological cycle such as the unsaturated or saturated zone, vegetation, atmosphere, or rivers. However, recent studies have shown that processes at the interfaces between the hydrological compartments (e.g., soil-atmosphere or soil-groundwater) govern the age distribution of the water fluxes between these compartments and thus can greatly affect water travel times. The broad variation from complete to nearly absent mixing of water at these interfaces affects the water ages in the compartments. This is especially the case for the highly heterogeneous critical zone between the top of the vegetation and the bottom of the groundwater storage. Here, we review a wide variety of studies about water ages in the critical zone and provide (1) an overview of new prospects and challenges in the use of hydrological tracers to study water ages, (2) a discussion of the limiting assumptions linked to our lack of process understanding and methodological transfer of water age estimations to individual disciplines or compartments, and (3) a vision for how to improve future interdisciplinary efforts to better understand the feedbacks between the atmosphere, vegetation, soil, groundwater, and surface water that control water ages in the critical zone.

Details

Original languageEnglish
Pages (from-to)800-834
Number of pages35
JournalReviews of geophysics
Volume57
Issue number3
Publication statusPublished - 1 Sept 2019
Peer-reviewedYes
Externally publishedYes

External IDs

ORCID /0000-0003-0407-742X/work/142242616
ORCID /0000-0003-4368-4580/work/163293731

Keywords

Sustainable Development Goals

ASJC Scopus subject areas

Keywords

  • critical Zone, stable isotopes, terrestrial water cycle, tracer hydrology, travel times, water ages