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| Titel |
Interplay of riparian forest and groundwater in the hillslope hydrology of Sudanian West Africa (northern Benin) |
| VerfasserIn |
A. Richard, S. Galle, Marc Descloitres, J.-M. Cohard, J.-P. Vandervaere, L. Séguis, C. Peugeot |
| 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 ; 17, no. 12 ; Nr. 17, no. 12 (2013-12-13), S.5079-5096 |
| Datensatznummer |
250086031
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| Publikation (Nr.) |
 copernicus.org/hess-17-5079-2013.pdf |
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| Zusammenfassung |
Forests are thought to play an important role in the regional dynamics of
the West African monsoon, through their capacity to extract water from
a permanent and deep groundwater table to the atmosphere even during the dry
season. It should be the case for riparian forests too, as these streambank
forests are key landscape elements in Sudanian West Africa.
The interplay of riparian forest and groundwater in the local hydrodynamics
was investigated, by quantifying their contribution to the water balance.
Field observations from a comprehensively instrumented hillslope in northern
Benin were used. Particular attention was paid to measurements of actual
evapotranspiration, soil water and deep groundwater levels. A vertical 2-D
hydrological modelling approach using the Hydrus software was used as a
testing tool to understand the interactions between the riparian area and
the groundwater. The model was calibrated and evaluated using a
multi-criteria approach (reference simulation). A virtual experiment,
including three other simulations, was designed (no forest, no groundwater,
neither forest nor groundwater).
The model correctly simulated the hydrodynamics of the hillslope regarding
vadose zone dynamics, deep groundwater fluctuation and actual
evapotranspiration dynamics. The virtual experiment showed that the riparian
forest transpiration depleted the deep groundwater table level and
disconnected it from the river, which is consistent with the observations.
The riparian forest and the deep groundwater table actually form an
interacting transpiration system: the high transpiration rate in the
riparian area was shown to be due to the existence of the water table,
supplied by downslope lateral water flows within the hillslope soil layer.
The simulated riparian transpiration rate was practically steady all year
long, around 7.6 mm d−1. This rate lies within high-end values of
similar study results. The riparian forest as simulated here contributes to
37% of the annual hillslope transpiration, and reaches 57% in the
dry season, whereas it only covers 5% of the hillslope area. |
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