Présentations Colloques

Poster
8.07
Session 8.07: Hydrogeophysics: innovative non-invasive technologies for groundwater resources exploitation and management
Gourdol (orateur)
Characterization of sub-surface heterogeneity with electrical resistivity tomography- new insights gained on hydrological functions in the Weierbach catchment (Luxembourg)
While being of highest relevance in catchment studies, subsurface regolith observations remain severely measurement limited. There is a pressing need for detailed information on the structure, properties and weathering states of the soil to bedrock continuum. Groundwater plays a key role in the fundamental hydrological functions of catchments, i.e. water storage and release. This subsurface information is indeed a prerequisite for a better understanding and prediction of water flow paths and transit times. However further progress is stymied by the “point-scale” character of most conventional measurement protocols. **Given their proven potential for investigating the subsurface, geophysical methods have received increasing attention in recent years within the hydrological sciences community. They inform on variations in physical properties and states that are of interest to hydrological investigations. For instance, electrical resistivity tomography (ERT) is now commonly used for mapping electrical resistivity in depth and space and, more recently, through time. In many studies, it has revealed static properties such as subsurface lithological structure and hydraulic pathways, as well as temporal changes in water content or solute concentration.**The Weierbach headwater experimental catchment (0.45 kmC) is a slate forested area of interest, representative of the Ardennes massif in northern Luxembourg. Previous studies have shown that shallow subsurface regolith plays a major role in runoff generation in this catchment. However a detailed understanding of this hidden compartment was still missing until very recently. In order to fill this knowledge gap, the Weierbach catchment has been extensively investigated, using ERT. Different types of ERT investigation were strategically deployed- catchment scale mapping to grasp the overall catchment structure, plot scale profiles to accurately characterize specific landscape units, as well as time-lapse survey to image dominant processes controlling subsurface flow. Through our case study, we illustrate how ERT investigations offer considerable potential for gaining new insights on fundamental catchment functions of water storage and release.**
Luxembourg