The Alps are often considered as the 'water towers of Europe'. Just as in other high mountain areas, annual precipitations are higher than in the surrounding lowlands. The snow that falls in the cold season is retained in snowfields and glaciers, from where it is slowly released during warmer periods to provide freshwater to springs, streams, rivers and aquifers. Nowhere in Central Europe is climate change so obvious as in the Alps, where rapidly retreating glaciers are the most visible expression of a changing climate. Relatively little research has been done on the current and future impacts of climate change on the water resources in the Alpine Space. Available studies suggest that warmer temperatures and more precipitation in the form of rain instead of snow may result in more available freshwater during the winter period, while less precipitation in summer, along with the shrinking or disappearance of glaciers, may result in local and temporal water shortage, particularly in late summer. There are few places in the Alps where the interrelations between climate change, retreating glaciers, groundwater resources and freshwater supply are so immediate as in the Tsanfleuron-Sanetsch region in Western Switzerland, where a rapidly retreating glacier (the Tsanfleuron glacier) directly overlies and recharges the upper part of a large regional karst aquifer, which is drained at its lowest point by a spring (the Glarey spring) used for the drinking water supply of a community (Conthey), as well as for irrigation purpose. The overall objective of the GLACIKARST project is to better understand the role of snow and glaciers for the recharge of alpine karst aquifers, sediment transport in these aquifers, and for the temporal variability of the discharge and water quality of karst springs. The measurement and experimental program in the Tsanfleuron test site includes geological and hydrogeological mapping, tracer tests, continuous monitoring of water temperatures, conductivity, turbidity and discharge, as well as stable isotope studies. During the first project phase, it was possible to characterise the unique recharge mechanisms, the underground drainage patters and the diurnal and seasonal variability of this karst aquifer system. The second project phase will focus more on reliable prognoses concerning the future evolution of this water resource and other comparable freshwater resources directly or indirectly connected to glaciers.