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Groundwater resources from karst aquifers play a major role in the water supply in karst areas in the world, such as in Switzerland. Defining groundwater protection zones in karst environment is frequently not founded on a solid hydrogeological basis. Protection zones are often inadequate and as a result they may be ineffective. In order to improve this situation, the Federal Office for Environment, Forests and Landscape with the Swiss National Hydrological and Geological Survey contracted the Centre of Hydrogeology of the Neuchâ-tel University to develop a new groundwater protection-zones strategy in karst environment. This approach is based on the vulnerability mapping of the catchment areas of water supplies provided by springs or boreholes. Vulnerability is here defined as the intrinsic geological and hydrogeological characteristics which determine the sensitivity of groundwater to contamination by human activities. The EPIK method is a multi-attribute method for vulnerability mapping which takes into consideration the specific hydrogeological behaviour of karst aquifers. EPIK is based on a conceptual model of karst hydrological systems, which suggests considering four karst aquifer attributes: (1) Epikarst, (2) Protective cover, (3) Infiltration conditions and (4) Karst network development. Each of these four attributes is subdivided into classes which are mapped over the whole water catchment. The attributes and their classes are then weighted. Attribute maps are overlain in order to obtain a final vulnerability map. From the vulnerability map, the groundwater protection zones are defined precisely. This method was applied at several sites in Switzerland where agriculture contamination problems have frequently occurred. These applications resulted in recommend new boundaries for the karst water supplies protection-zones.

In order to achieve some consistency in the establishment of groundwater intrinsic vulnerability maps in Europe, a new approach is proposed by Working Group 1 of the European COST Action 620 on "Vulnerability mapping for the protection of carbonate (karst) aquifers". A general procedure is offered which provides consistency while allowing the required flexibility for application to a continent and under conditions of varying geology, scale, information availability, time, and resources.The proposed methodology is designed to be clearly more physically based than the existing vulnerabilitymapping techniques. It takes the specificity of the karstic environments into account without necessarily excluding the applicability to other geological conditions. Combined "core factors" for overlying layers and for concentration of flow account for the relative protection of groundwater from contamination while taking into account any bypass of the overlying layers.A precipitation factor is distinguished for describing characteristics of the input of water to the system. Differentiation is made between groundwater resource intrinsic vulnerability mapping and source intrinsic vulnerability mapping. For the latter, a factor describing the karst network development is relevant. This short technical note describes a first step in the work program of Working Group 1 of the COST Action 620. Future steps are now in progress to quantify the approach and to apply it in various European pilot areas.Résumé Pour atteindre, au niveau européen, une certaine cohérence dans l'établissement de cartes de vulnéra-bilité des eaux souterraines, une approche originale est proposée par le Groupe de Travail 1 de l'Action européenne COST 620 "Cartographie de la vulnérabilité pour la protection des aquifères carbonatés (karstiques)". La procédure générale présentée ici est très flexible afin de permettre des applications dans tout un continent, pour différentes conditions géologiques, à des échelles variables, et à l'aide de données et de ressources diverses.La méthodologie proposée est conçue pour être plus compatible avec la physique des processus que ne le sont les méthodes existantes de cartographie de la vulnérabili-té. Elle tient compte des spécificités des milieux karstiques sans pour autant exclure son applicabilité dans d'autres contextes géologiques. Des facteurs principaux tenant compte des couches supérieures et de la concentration des flux d'infiltration permettent de tenir compte du degré relatif de protection des eaux souterraines en tenant compte de toutes les infiltrations préférentielles possibles qui évitent les couches supérieures protectrices.Un facteur dit précipitation est distingué pour décrire les caractéristiques de l'entrée d'eau dans le système. Une différence est faite entre les cartes de vulnérabilité intrinsèque des ressources en eaux souterraines et les cartes de vulnérabilité intrinsèque relatives à une source ou émergence. Pour ce dernier type de cartes, un paramè-tre décrivant le développement du réseau kar...

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 lm) 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.

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