Journal Article

PreJuSER-22331

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Factors controlling the isotopic partitioning between soil evaporation and plant transpiration: Assessment using a multi-objective calibration of SiSPAT-Isotope under controlled conditions

Rothfuss, Y.FZJ* ; Braud, I. ; Le Moine, N. ; Biron, P. ; Durand, J. L. ; Vauclin, M. ; Bariac, T.

2012
Elsevier Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.jhydrol.2012.03.041

Abstract: Stable isotopes of water (O-18 and H-2) are tracers of ecosystem processes and in particular of water vapour sources. They have been substantially used for evapotranspiration (ET) studies. Data gathered during a series of soil monoliths experiments under fully controlled conditions allowed the partitioning of ET fluxes into soil evaporation (Ev) and plant transpiration (Tr) from isotopic measurements along growth of a tall fescue cover. These data were used to calibrate SiSPAT-Isotope, a 1D Soil-Vegetation-Atmosphere Transfer (SVAT) model coupled with a module for isotopic transport in the soil and the atmosphere. For this, the soil isotopic module was extended to take into account plant water uptake by roots and the model was modified so that it could be constrained with collected input data (e.g. ET flux). The multi-objective calibration method allowed determining narrowed probability distributions for soil, plant and isotopic parameters of which some are currently debated and/or typically not measured in the field (e.g. kinetic fractionation factor during soil evaporation). Comparisons between simulation results corresponding to the "best compromise" parameter set with data (i.e. soil water pressure and contents, soil temperatures and heat fluxes, soil isotopic compositions, and root extraction depths) were provided to show the consistency of the calibration method. Guidelines were provided for the determination of the isotopic composition of evaporation in the field: we could emphasize the importance of values used for the kinetic fractionation factor and the impact of the heights at which atmospheric variables (air relative humidity and temperature, isotopic composition of atmospheric water vapour) are measured in the field. (C) 2012 Elsevier B.V. All rights reserved.

Keyword(s): J ; SiSPAT-Isotope model (auto) ; Water stable isotopes (auto) ; Partitioning of evapotranspiration (auto) ; Multi-objective model calibration (auto) ; Kinetic fractionation factor (auto)

Note: We thank the PNRH Thematic Action of the French ECCO (ECosphere COntinentale) program for providing part of the financial support of the study. We thank Ludovic Oudin (UMR Sisyphe) for his helpful commentaries all along the writing of the manuscript.

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Contributing Institute(s):

1. Agrosphäre (IBG-3)

Research Program(s):

1. Terrestrische Umwelt (P24)

Appears in the scientific report 2012

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Database coverage:
BIOSIS Previews ; Current Contents - Agriculture, Biology and Environmental Sciences ; Current Contents - Engineering, Computing and Technology ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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