The Alpine-Himalayan orogenic belt is one of the longest geological structures in the world. Along with several parallel or sub-parallel branches, the central structure extends from the Alps to the Himalayan peaks across SE Europe and the Near and Middle East to the Indian sub-continent. The focus of this article is the section from the Alpine Mts. to the Zagros Mt. Range, where karst aquifers' presence is much greater, and they are utilised more frequently than in the Indian sub-continent. The carbonates in the north-western "European sub-unit" as well as carbonate and evaporitic rocks in the "Asian sub-unit" in the south-eastern parts of the belt are widely present, extending over 20-30% of the land surface. Due to the wet climate and presence of highly karstified rocks, certain countries in the Alpine region are among the richest in the world concerning water availability: in Montenegro, approximately 21,000 m(3) of water per year is available to each citizen, while Bosnia & Herzegovina and Croatia utilise just 1-2% of their water resources. In contrast, because of the arid climate and extended periods of drought, many areas of the Zagros region, such as Iraq or southern Iran, where karst aquifers are sometimes even the sole source for local potable water supply and irrigation of fertile lands, experience water shortages.