Abstract
Facing changes in climate, land cover, uses and water management strategies, socio-hydrosystems are evolving towards trajectories that sometimes break with those of the past: Water shortages in some basins engendering social tensions or crises, extreme events generating violent and devastating runoffs or floods and paralyze the social and economic organization of large cities around the world ... Observing the processes that operate on socio-hydrosystems or the impacts of the changes is essential for a better understanding of their characteristics or anticipating their evolution. These observations are no longer the sole concern of professionals; citizens can prove to be particularly useful to the system by contributing to the improvement of scientific knowledge and in return can themselves benefit from scientific or social recognition. Thus participatory observatories can help to answer scientific questions and societal and environmental issues. Three examples of participatory hydrological observatories led by teams of researchers are presented to illustrate our remarks: an international and interdisciplinary field school in the Mediterranean region; a hydrometeorological, participatory and low-cost observatory in a tropical climate; an observation system for the impacts of floods (so-ii) in the Mediterranean climate.