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

Manipulation experiments to infer the age and tracer composition of hydrologic fluxes

Mitra Asadollahi1, Paolo Benettin1, Magali Nehemy2, Andrea Rinaldo1,3, and Jeffrey McDonnell2,4,5
Mitra Asadollahi et al.
  • 1EPFL ( École polytechnique fédérale de Lausanne), GR C1 557 (Bâtiment GR, ECHO lab) ,Station 2,CH-1015 Lausanne, Environmental Sciences and Engineering, Lausanne, Switzerland (
  • 2Global Institute for Water Security, School of Environment and Sustainability, University of Saskatchewan, Saskatoon, CA
  • 3Department ICEA, University of Padova, Padova, IT
  • 4School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, UK
  • 5School of Resources and Environmental Engineering, Ludong University, Yantai, CN

Several ecohydrological problems such as when and where precipitation becomes the source of plant uptake are usually tackled through stable isotope measurements. Our ability to go after these questions is often limited by field conditions that cannot be controlled, but targeted manipulation experiments can go beyond some of these limitations by imposing known boundary conditions and allowing the experimental closure of the isotope balance. This contribution presents examples from existing experiments that aim to understand which water, in terms of age and tracer composition, is uptaken by vegetation or drained to deeper soil horizons. In particular, we illustrate the Spike II experiment, which was carried out on a large vegetated lysimeter within the EPFL campus (CH) in 2018. This experiment featured the application of 40 mm of isotopically-enriched water on top of the lysimeter and its tracking for 40 days through the soil water, the lysimeter bottom drainage and the plant xylem. A total of more than 900 water samples were collected to reconstruct the “story” of the labeled precipitation. The detailed results from such controlled experiments represent a fundamental “ground truth” for our understanding of root water uptake patterns in large and diverse landscapes.

How to cite: Asadollahi, M., Benettin, P., Nehemy, M., Rinaldo, A., and McDonnell, J.: Manipulation experiments to infer the age and tracer composition of hydrologic fluxes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8134,, 2020

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