HYdrological cycle in the Mediterranean EXperiemnt. Considering the science and societal issues motivating HyMeX, the programme aims to : improve our understanding of the water cycle, with emphasis on extreme events, by monitoring and modelling the Mediterranean atmosphere-land-ocean coupled system, its variability from the event to the seasonal and interannual scales, and its characteristics over one decade (2010-2020) in the context of global change, assess the social and economic vulnerability to extreme events and adaptation capacity.The multidisciplinary research and the database developed within HyMeX should contribute to: improve observational and modelling systems, especially for coupled systems, better predict extreme events, simulate the long-term water-cycle more accurately, provide guidelines for adaptation measures, especially in the context of global change.