Karstified carbonate rocks constitute 21.6 % of the European land surface and contain abundant groundwater resources. These karst aquifers contribute substantially to the freshwater supply of most Mediterranean countries and many large cities, e.g., Rome and Beirut. However, karst aquifers are highly variable in terms of water availability and quality, and vulnerable to contamination and climate change. Therefore, they require specific investigation and management approaches. The main objective of the proposed KARMA project is to achieve substantial progress in the hydrogeological understanding and sustainable management of karst water resources across several scales. Based on our recently accomplished World Karst Aquifer Map, the project will deliver a detailed karst aquifer map at the scale of the entire Mediterranean area with valuable information, noticeably for stakeholders, on recharge, groundwater vulnerability and groundwater-dependent ecosystems. At catchment scale, five karst systems in Spain, France, Italy, Lebanon and Tunisia will serve as field observatories. Tracer tests, hydrologic monitoring and isotope studies will be applied to better quantify recharge and dynamic water balances. New generic models will allow a better understanding of karst hydrodynamic processes at different spatiotemporal scales, and thus better predictions concerning climatic and human impacts. At local scale, novel early-warning systems for microbial and chemical contamination will be developed, based on water-quality monitoring at karst springs. The resulting karst aquifer map will be a major tool for stakeholders and governments for transboundary water resources management in the entire Mediterranean region. The new generation of modeling tools proposed in this project will allow better long-term predictions of climate-change impacts and improved management decisions. Early-warning systems will be useful for water suppliers to identify short-term contamination at springs.