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| Titel |
Multi-criteria assessment of the Representative Elementary Watershed approach on the Donga catchment (Benin) using a downward approach of model complexity |
| VerfasserIn |
N. Varado, I. Braud, S. Galle, M. Lay, L. Séguis, B. Kamagate, C. Depraetere |
| 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 ; 10, no. 3 ; Nr. 10, no. 3 (2006-06-08), S.427-442 |
| Datensatznummer |
250008065
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| Publikation (Nr.) |
 copernicus.org/hess-10-427-2006.pdf |
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| Zusammenfassung |
| This study is part of the AMMA - African Multidisciplinary Monsoon
Analysis- project and aims at a better understanding and modelling of the
Donga catchment (580 km2, Benin) behaviour in order to determine its
spatially distributed water balance. For this purpose, we applied the REW
concept proposed by Reggiani et al. (1998, 1999), which allows the
description of the main local processes at the sub-watershed scale. Such
distributed hydrological models, which represent hydrological processes at
various scales, should be evaluated not only on the discharge at the outlet
but also on each of the represented processes and in several points of the
catchment. This multi-criteria approach is required in order to assess the
global behaviour of hydrological models. We applied such multi-criteria
strategy to the Donga catchment (586 km2), in Benin. The work was
supported by an observation set up, undertaken since 1998 consisting in a
network of 20 rain gauges, an automatic meteorological station, 6 discharge
stations and 18 wells.
The main goal of this study was to assess the model's ability to reproduce
the discharge at the outlet, the water table dynamics in several points of
the catchment and the vadose zone dynamics at the sub-catchment scale. We
tested two spatial discretisations of increasing resolution. To test the
internal structure of the model, we looked at its ability to represent also
the discharge at intermediate stations. After adjustment of soil parameters,
the model is shown to accurately represent discharge down to a drainage area
of 100 km2, whereas poorer simulation is achieved on smaller
catchments. We introduced the spatial variability of rainfall by
distributing the daily rainfall over the REW and obtained a very low
sensitivity of the model response to this variability. Simulation of
groundwater levels was poor and our results, in conjunction with new data
available at the local scale, suggest that the representation of the
processes in the unsaturated zone should first be improved, in order to
better simulate soil water dynamics and represent perched water tables which
were not included in this first modelling study. |
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