Présentations Colloques

Oral Presentation
6.03
Session 6.03: Innovative tools to improve understanding of groundwater recharge processes
Ollivier Chloé
Semi-distributed lumped model to assess recharge of karst unsaturated zone
The unsaturated zone (UZ) is the poor relation of karst hydrodynamics. However, it governs spring discharge during low flow periods (e.g. Chen et al., 2016), it is a major water storage entity (Emblanch et al., 2003) and thus plays a key role in karst recharge and contaminant attenuation processes (Lastennet et al., 1995). Much more emphasis has been placed on epikarst and saturated zone characterization and hydrodynamics modelling. A qualitative assessment of the UZ dynamics have been proposed in mapping vulnerability methods (e.g- Dörflinger et Plagnes, 2009, Goldscheider, 2005) but quantitative assessment is required for groundwater management.**Lumped models are usual tools for rainfall-discharge relationship modelling. They are often preferred to physically-based gridded flow models for karst hydrodynamics modelling because of the complexity and lack of detailed knowledge on the geometry of karst hydrosystems. Lumped models, although simple, can reproduce with a high quality the rainfall-discharge relationship (e.g. Marsaud, 1996+ Fleury, 2005) of karst hydrosystems. But due to their 1D construction, they can’t bring insights into the spatial distribution of reserves (e.g. Tritz, 2011). This limitation is critical for resources management.**The final goal of this study is to assess to the spatiotemporal distribution of the recharge of the UZ using a semi-distributed model on the Fontaine-de-Vaucluse catchment area. For that, a sensitivity analysis of the existing lumped model (Fleury et al., 2007) of the site was mandatory and highlighted the crucial hydrological role of the soil and the unsaturated compartments. Additionally, we combined a climate model with the hydrological model and suggest a non-negligible effect of rainfall distribution, which is a key point for understanding impact of climate changes on groundwater. The architecture of the semi distributed lumped model of the UZ is accordingly proposed.
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