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Zwahlen, François
Nom
Zwahlen, François
Affiliation principale
Fonction
Professeur.e émérite
Email
francois.zwahlen@unine.ch
Identifiants
Résultat de la recherche
Voici les éléments 1 - 10 sur 53
- PublicationMétadonnées seulementPercolation and Particle Transport in the Unsaturated Zone of a Karst Aquifer(2009)
; ; Recharge and contamination of karst aquifers often occur via the unsaturated zone, but the functioning of this zone has not yet been fully understood. Therefore, irrigation and tracer experiments, along with monitoring of rainfall events, were used to examine water percolation and the transport of solutes, particles, and fecal bacteria between the land surface and a water outlet into a shallow cave. Monitored parameters included discharge, electrical conductivity, temperature, organic carbon, turbidity, particle-size distribution (PSD), fecal indicator bacteria, chloride, bromide, and uranine. Percolation following rainfall or irrigation can be subdivided into a lag phase (no response at the outlet), a piston-flow phase (release of epikarst storage water by pressure transfer), and a mixed-flow phase (increasing contribution of freshly infiltrated water), starting between 20 min and a few hours after the start of recharge event. Concerning particle and bacteria transport, results demonstrate that (1) a first turbidity signal occurs during increasing discharge due to remobilization of particles from fractures (pulse-through turbidity); (2) a second turbidity signal is caused by direct particle transfer from the soil (flow-through turbidity), often accompanied by high levels of fecal indicator bacteria, up to 17,000 Escherichia coli/100 mL; and (3) PSD allows differentiation between the two types of turbidity. A relative increase of fine particles (0.9 to 1.5 mu m) coincides with microbial contamination. These findings help quantify water storage and percolation in the epikarst and better understand contaminant transport and attenuation. The use of PSD as "early-warning parameter" for microbial contamination in karst water is confirmed. - PublicationMétadonnées seulementIntegrated vulnerability and risk mapping - a multi-purpose groundwater management tool(: Presses Universitaires de Franche-Comté, 2008)
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- PublicationMétadonnées seulementNatural radionuclides in gorundwater as pollutants and as useful tracers(2007)
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- PublicationMétadonnées seulementKarst groundwater protection: First application of a Pan-European Approach to vulnerability, hazard and risk mapping in the Sierra de Libar (Southern Spain)(2006)
- PublicationMétadonnées seulementProceedings of the 8th conference on limestone hydrogeology(: Presses Universitaires de Franche-Comté, 2006)
- PublicationMétadonnées seulementEvaluation de la vulnérabilité des eaux souterraines karstiques et du risque de contamination?Adaptation et application des concepts européens en Suisse(2005)
- PublicationMétadonnées seulementVulnerability, Hazard and Risk Mapping for the Protection of Carbonates (Karst) Aquifers(2004)
; Goldscheider, Nico