The scientific and managerial analysis of a river ecosystem requires a vision that transcends simple hydraulic observation, embracing a biological, geomorphological and socio-economic complexity. A river is an open and dynamic system, responsible for transporting energy, inorganic sediments, nutrients and organic matter from mountain peaks to alluvial plains and, finally, to the oceans. The vitality of this system depends on its ability to maintain fluid connectivity across interconnected spatial and temporal dimensions, guaranteeing fundamental ecosystem services for human survival, from the recharge of underground aquifers to the mitigation of extreme climate events.