AbstractThe work presented in this thesis manuscript aimed at studying flow an
d transport phenomena within karst aquifers, being one of the main groundwater resources on Earth. Those carbonated aquifers are very specific due to the presence of solution erosion processes and exhibit behavior heterogeneities that are difficult to assess with routine methodologies. However, existence of karstic cavities is an incredible
opportunity to study those systems from the inside. The knowledge of accessible speleological networks allows the implementation of in situ monitoring solutions. This approach has been achieved in the Givetian limestones karst aquifer, South of Belgium. This aquifer shows a large number of karst features, including two major active karst systems: the Han-sur-Lesse karst system and the Lomme karst system. These systems were chosen as study sites to perform two experimental approaches.
On the one hand, we investigated the phreatic zone of karst, which means the part of the karst aquifer which is constantly saturated with water and where significant underground flows are found. Cave based monitoring and dye tracing experiments allow refining the knowledge about the complex Wamme and Lomme underground streams in the Lomme karst system.
On the other hand, we performed a second approach focused on the unsaturated zone. This zone, also called the vadose zone, is crucial because it forms the transition between the surface and the phreatic zone. It is the main support for all phenomena occurring from the surface. Cave access allows the measurement of transport and storage processes of the infiltration water. This approach gives a clear characterization and quantification of aquifer recharge mechanisms. The vulnerability of karst groundwater regarding surface contamination has also been estimated.
This PhD thesis is part of a broader research project, the KARAG project (Karst
Aquifer ReseArch by Geophysics) which aim characterizing the hydrogeolo
gical processes in the vadose zone of karst aquifers by means of a multidisciplinary and multi-scale approach. The KARAG project gathers experiences in hydrogeology and near surface geophysics to build a comprehensive experimental approach.
|Date of Award||6 Sep 2017|
|Sponsors||Fonds de la Recherche Scientifique F.R.S.-FNRS|
|Supervisor||Vincent Hallet (Supervisor), Johan Yans (President), Pascal Goderniaux (Jury), Hervé Jourde (Jury), Olivier Kaufmann (Jury) & Marnick Vanclooster (Jury)|
Attachment to an Research Institute in UNAMUR