Lay summary
Karst aquifers are among the most important drinking water resources for humanity. At the same time, due to their special characteristics (extreme anisotropy and heterogeneity), they are particularly vulnerable to contamination. The project BEKARST aims at a better understanding of flow, solute transport and biological processes in karst hydrogeology systems.It is subdivided into three sub-projects: KARSTDYN, KARSTMOD and GLACIKARST.
KARSTDYN: The dynamics and interaction of organic carbon, microorganism and mineral particles in karst flow systems implies different processes that we identify and better understand. The site is fully equipped with measurement instruments (continuous data records of OC, turbidity, temperature, conductivity and discharge, as well as standard hydrochemical and microbiological parameters from water samples) and an online Particle Counter also record continuously the particle-size distribution (PSD) of the spring water. The microbial communities in the aquifer system and their variability during flood events are also caracterised by using different methods such as PCR-DGGE.
KARSTMOD: Flow in karst is largely conditioned by flow through conduits.Complex networks of conduits, as present in karst networks, induce a specific behaviour to karst hydrological systems, especially strong non-linearity. Numerical models able to cope with such complex networks are being developed based on the resolution of the Saint-Venant equations.
GLACIKARST: The impact of a retreating alpine glacier on groundwater flow and transport processes in a directly linked karst aquifer is effective in the Tsanfleuron area (Western Swiss Alps), which consists of a karst aquifer partly overlained by a glacier. The project will assess the impact of hazards on the groundwater quality and highlight the role of ice and snow for the storage and remobilisation of contaminants. Glacier meltwaters are characterised by high contents of suspended mineral particles. Turbidity in karst groundwater may also result from soil erosion and remobilisation of sediments in the conduit network. The project will investigate the different types of turbidity and the mechanisms of particle transport, as well as the relation between turbidity and bacteria transport.