The research carried out by the EMMAH joint research (UMR) unit focuses on understanding and modelling the functioning of agrosystems in interaction with underground hydrosystems. This leads the EMMAH UMR to consider the aquifer-soil-plant-atmosphere system on different time and space scales. In order to understand and model how this system works, it is necessary to take into account the many interactions between the dynamics of the plant cover, the physical, chemical and biological processes in the soil, interactions with the atmosphere and hydrosystems, and the way in which agrosystems are managed. In particular, the work carried out aims to characterise mass flows between the atmosphere, the plant cover, the soil and the underground aquifer, and the processes involved in plant production in relation to environmental factors, at different spatial scales (from a millimetre to a kilometre) and temporal scales (from a second to several decades). In this way, the EMMAH joint research unit is helping to assess the sustainability of underground water resources and cropping systems in the dual context of global change and agro-ecological transition. The Mediterranean remains a key area of study, a region marked by rapid climate change and high water stress linked to the adaptation of cropping systems and strong demographic pressure.