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@ARTICLE{Vanderborght:904455,
author = {Vanderborght, Jan and Couvreur, Valentin and Meunier,
Felicien and Schnepf, Andrea and Vereecken, Harry and Bouda,
Martin and Javaux, Mathieu},
title = {{F}rom hydraulic root architecture models to macroscopic
representations of root hydraulics in soil water flow and
land surface models},
journal = {Hydrology and earth system sciences},
volume = {25},
number = {9},
issn = {1027-5606},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2021-06025},
pages = {4835 - 4860},
year = {2021},
abstract = {Root water uptake is an important process in the
terrestrial water cycle. How this process depends on soil
water content, root distributions, and root properties is a
soil–root hydraulic problem. We compare different
approaches to implement root hydraulics in macroscopic soil
water flow and land surface models. By upscaling a
three-dimensional hydraulic root architecture model, we
derived an exact macroscopic root hydraulic model. The
macroscopic model uses the following three characteristics:
the root system conductance, Krs, the standard uptake
fraction, SUF, which represents the uptake from a soil
profile with a uniform hydraulic head, and a compensatory
matrix that describes the redistribution of water uptake in
a non-uniform hydraulic head profile. The two
characteristics, Krs and SUF, are sufficient to describe the
total uptake as a function of the collar and soil water
potential, and water uptake redistribution does not depend
on the total uptake or collar water potential. We compared
the exact model with two hydraulic root models that make a
priori simplifications of the hydraulic root architecture,
i.e., the parallel and big root model. The parallel root
model uses only two characteristics, Krs and SUF, which can
be calculated directly following a bottom-up approach from
the 3D hydraulic root architecture. The big root model uses
more parameters than the parallel root model, but these
parameters cannot be obtained straightforwardly with a
bottom-up approach. The big root model was parameterized
using a top-down approach, i.e., directly from root segment
hydraulic properties, assuming a priori a single big root
architecture. This simplification of the hydraulic root
architecture led to less accurate descriptions of root water
uptake than by the parallel root model. To compute root
water uptake in macroscopic soil water flow and land surface
models, we recommend the use of the parallel root model with
Krs and SUF computed in a bottom-up approach from a known 3D
root hydraulic architecture.},
cin = {IBG-3},
ddc = {550},
cid = {I:(DE-Juel1)IBG-3-20101118},
pnm = {2173 - Agro-biogeosystems: controls, feedbacks and impact
(POF4-217)},
pid = {G:(DE-HGF)POF4-2173},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000693695500002},
doi = {10.5194/hess-25-4835-2021},
url = {https://juser.fz-juelich.de/record/904455},
}