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| Titel |
Evaluation of root water uptake in the ISBA-A-gs land surface model using agricultural yield statistics over France |
| VerfasserIn |
N. Canal, J.-C. Calvet, B. Decharme, D. Carrer, S. Lafont, G. Pigeon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 12 ; Nr. 18, no. 12 (2014-12-10), S.4979-4999 |
| Datensatznummer |
250120553
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| Publikation (Nr.) |
 copernicus.org/hess-18-4979-2014.pdf |
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| Zusammenfassung |
| The simulation of root water uptake in land surface models is affected by large uncertainties. The
difficulty in mapping soil depth and in describing the capacity of plants to
develop a rooting system is a major obstacle to the simulation of the
terrestrial water cycle and to the representation of the impacts of drought.
In this study, long time series of agricultural statistics are used to
evaluate and constrain root water uptake models. The inter-annual variability
of cereal grain yield and permanent grassland dry matter yield is simulated
over France by the Interactions between Soil, Biosphere and Atmosphere,
CO2-reactive (ISBA-A-gs) generic land surface model (LSM). The two soil
profile schemes available in the model are used to simulate the above-ground
biomass (Bag) of cereals and grasslands: a two-layer
force–restore (FR-2L) bulk reservoir model and a multi-layer diffusion (DIF)
model. The DIF model is implemented with or without deep soil layers below
the root zone. The evaluation of the various root water uptake models is
achieved by using the French agricultural statistics of Agreste over the
1994–2010 period at 45 cropland and 48 grassland départements, for a
range of rooting depths. The number of départements where the simulated
annual maximum Bag presents a significant correlation with the
yield observations is used as a metric to benchmark the root water uptake
models. Significant correlations (p value < 0.01) are found for up to
29 and 77% of the départements for cereals and grasslands,
respectively. A rather neutral impact of the most refined versions of the
model is found with respect to the simplified soil hydrology scheme. This
shows that efforts should be made in future studies to reduce other sources
of uncertainty, e.g. by using a more detailed soil and root density profile
description together with satellite vegetation products. It is found that
modelling additional subroot-zone base flow soil layers does not improve (and
may even degrade) the representation of the inter-annual variability of the
vegetation above-ground biomass. These results are particularly robust for
grasslands, as calibrated simulations are able to represent the extreme 2003
and 2007 years corresponding to unfavourable and favourable fodder
production, respectively. |
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