Hydrogeological dynamic variability in the Lomme Karst System (Belgium) as evidenced by tracer tests results (KARAG Project)

Amael Poulain, Gaëtan Rochez (Collaborator), Vincent Hallet (Supervisor)

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Abstract

Paleozoic carbonate aquifers represent major
groundwater resources in Belgium. Karstification
processes affect most of them and Belgium counts
many hydrologically active karst networks. Given the
intrinsic vulnerability of such geology, comprehensive
studies are required in order to improve their protection
and management.
The KARAG project (Karst Aquifer ReseArch by
Geophysic, 2013-2017) aims to identify the specific
dynamic of karst aquifers by using geophysical and
hydrogeological tools. This research is funded by the
Belgium National Fund for Scientific Research (FNRS)
and conducted by the University of Namur, University of
Mons and the Royal Observatory of Belgium.
The LKS – Lomme Karst System (Rochefort, southern
Belgium) was chosen as it is a major Belgian karst
system (10 km long) in the Givetian carbonate aquifer
(Middle Devonian). The system is formed by two parallel
components: the surface system (the Lomme River) and
a complex underground system (multiple sinkholes with
one main resurgence). Based on this layout, it is possible
to study the aquifer dynamic and its relationship with the
surface river.
A high resolution monitoring network has been in place
since July 2013 in order to follow the system dynamic
during several hydrogeological cycles.
Multi-tracing experiments with different injections
and monitoring points highlight the complexity
of underground flow dynamics. Investigations
enlightened the connectivity between monitoring
points and how dependent of the hydrological
conditions were these connections. The breakthrough
curves analysis allows to characterize the
hydrodynamic behavior of the underground flows
within the aquifer.
Modeling will be necessary to link hydrological and
tracer tests data in order to build a detailed conceptual
model for this karst system. This model will also be
used to interpret geophysical data (ERT, gravimetry)
collected in order to study the unsaturated and epikarst
zones.
Translated title of the contributionMise en évidence par essais de traçage de la variabilité de la dynamique hydrogéologique du système karstique de la Lomme (Projet KARAG)
Original languageEnglish
Title of host publicationNCKRI Symposium 5 : Proceedings of the Fourteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst
Place of PublicationCarlsbad
PublisherNational Cave and Karst Research Institute
Number of pages7
Publication statusAccepted/In press - 2015

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