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Genre/Form: | Thèses et écrits académiques |
---|---|
Material Type: | Document, Thesis/dissertation, Internet resource |
Document Type: | Internet Resource, Computer File |
All Authors / Contributors: |
Aloïs Richard; Marc Descloitres; Sylvie Galle; Eric Barthélémy, physicien hydraulicien).; Philippe Mérot; Agnès Ducharne; Isabelle Braud; Université de Grenoble (2009-2014).; École doctorale terre, univers, environnement (Grenoble).; Laboratoire d'étude des transferts en hydrologie et environnement (Grenoble). |
OCLC Number: | 992155096 |
Notes: | Titre provenant de l'écran-titre. |
Description: | 1 online resource |
Responsibility: | Aloïs Richard ; sous la direction de Marc Descloitres et de Sylvie Galle. |
Abstract:
Understanding how the hydrological cycle and water resources availability evolve in the current context of global change (which encompass climate, environmental and population changes) is a critical issue, particularly in West Africa, where at regional scale, strong interannual and seasonal variabilities overlap with highly uncertain climate predictions. Within this framework, this work aims at improving our knowledge of the behavior of the Upper Oueme catchment in Benin (Sudanian climate), with an analysis of all the hydrological processes and terms of the terrestrial hydrological cycle.First, the hillslope scale is considered by using the Hydrus 2D software and field observations from the hydrometeorological observing system AMMA-CATCH: rainfall, actual evapotranspiration, soil moisture, groundwater level and river runoff. The principal result of this analysis is that the riparian forest transpiration depletes the deep groundwater and disconnects it from the river network. Water supply by the deep groundwater enables the riparian forest transpiration all year long and particularly during the dry season. Seepage of unsaturated subsurface lateral flows contributes to river runoff, but the "bas-fonds" seem to be other important contributors.Then, at mesoscale, we quantify the impact of the spatial variability of hydraulic conductivity on the simulated water balance, with focus on the evapotranspiration term. The numerical model nTopAMMA, especially derived from the TopMODEL hydrological model for the Upper Oueme catchment, is used here. Measurements from a specific field mission evidence the correlation between the hydraulic conductivity spatial variability and the land use one. By taking into account this variability, the simulation results show that evapotranspiration and water storage simulated on the Upper Oueme catchment at local (pixel) scale depend essentially on the topography (75 %) and to a lesser extent on the hydraulic conductivity (25 %).Finally, a bottom-up approach is adopted to analyse the hydrological modelling results at mesoscale, taking advantage of the modelling results at the hillslope scale. Vertical processes and fluxes simulated by nTopAMMA are analyzed. It is shown that an improvement of the Upper Oueme hydrological cycle modelling, with nTopAMMA, requires: (i) the consideration of the catchment heterogeneities, (ii) the modification of the evapotranspiration module, (iii) the diversification of the evapotranspiration sources and (iv) the integration of the deep groundwater reservoir.
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Related Subjects:(7)
- Cycle hydrologique.
- Ressources en eau.
- Modélisation
- Hydrus 2D
- TopMODEL
- AMMA-CATCH
- Afrique de l'Ouest