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Critical zone storage control on the water ages in ecohydrological outputs
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  • Sylvain Kuppel,
  • Doerthe Tetzlaff,
  • Marco P Maneta,
  • Chris Soulsby
Sylvain Kuppel
Institut De Physique Du Globe De Paris

Corresponding Author:sylvain.kuppel@irstea.fr

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Doerthe Tetzlaff
Aberdeen University
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Marco P Maneta
University of Montana
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Chris Soulsby
University of Aberdeen
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Spatially-explicit knowledge of the origins of water resources for ecosystems and rivers is challenging when using tracer data alone. We use simulations from a spatially-distributed model calibrated by extensive ecohydrological datasets in a small, energy-limited catchment, where hillslope-riparian dynamics are broadly representative of humid boreal headwater catchments that are experiencing rapid environmental transition. We hypothesize that in addition to wetness status, landscape heterogeneity modulates the water pathways that sustain ecosystem function and streamflows. Simulations show that catchment storage inversely controls streamwater ages year-round, but only during the drier seasons for transpiration and soil evaporation. The ages of these evaporative outputs depend much less on wetness status in the oft-saturated riparian soils than on the freely-draining hillslopes that subsidize them. This work highlights the need to consider local dynamics and time-changing lateral heterogeneities when interpreting the ages, and thus the vulnerability, of water resources feeding streams and ecosystems in landscapes.
28 Aug 2020Published in Geophysical Research Letters volume 47 issue 16. 10.1029/2020GL088897