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How informative is land-cover for the regionalization
of the GR4J rainfall–runoff model? Lessons of a downward approach
Ludovic Oudin1, Vazken Andréassian2, Cécile Loumagne2 &
Claude Michel2
1 Université Pierre-et-Marie Curie, UMR 7619
Sisyphe, Case 105, 4 Place Jussieu,
75252 Paris cedex 5, France
ludovic.oudin@ccr.jussieu.fr
2 Cemagref, Hydrology and Water Quality Research Unit, PB 44, 92163 Antony cedex, France
Abstract Prediction on ungauged basins is a big issue for operational hydrology and a challenge for scientists. For regionalization objectives, the first step of the development of a priori parameter estimation is to look for correlations between calibrated parameters and physical catchment descriptors. This article investigates the relationships between the parameters of the GR4J rainfall–runoff model and catchment vegetation characteristics over a large sample of 221 French catchments. First, the possible links between the calibrated parameters of the GR4J model and catchment vegetation types are investigated by linear regression. Then, we try to improve these relationships by introducing a more detailed description of the evapotranspiration process, explicitly taking into account vegetation types, following a downward approach. Results show that the GR4J model parameters cannot be determined directly from vegetation characteristics, and that the situation is not improved by a more detailed approach to evapotranspiration modelling.
Key words
downward
approach; evapotranspiration; land use; rainfall–runoff
model; regionalization