Verbreitung von Carbonatgesteinen und Karstwasserressourcen im Alpenraum = Distribution of carbonate rocks and karst water resources in the European Alpine region

Groundwater resources in alpine karst systems are used by many cities and communities for drinking water supply and feed diverse groundwater-dependent ecosystems. This study is the first to quantify the distribution of carbonate rocks and karst water resources in the European Alpine region. Around 76,000 km$^2$ (40%) of the Alps consist of exposed carbonate rocks. The Austrian Alps show the largest carbonate rock area (21,000 km2), while the French Alps have the highest proportion (51%). Since the highest mountain groups mostly consist of crystalline rocks, only a relatively small proportion of the Alpine glaciers (10.7%) are located in karst areas. The Alps are home to some of the deepest and longest caves as well as one of the largest karst water supplies (Vienna) in the world. Through a combination of climate data and the karst map, groundwater recharge and sustainably available groundwater resources could be estimated: the long-term (1991–2020) average annual recharge in the European Alpine karst areas is around 823 mm, corresponding to renewable Alpine karst water resources of about 57,500 million cubic meters per year. These data form the basis for improved management of Alpine karst water resources.