The objective of this research is to gain knowledge in the process of basin closure of a Mediterranean European river. The paper analyses the evolution of water demand and interactions between users and water resources, focusing on irrigation as the main actor of change. The Guadalquivir River Basin has been managed through a centralized and hierarchical system for almost 80 years, which facilitated the evolution of a large and profitable agricultural sector that in turn has driven the basin towards closure, defined as those basins with a relatively small amount of uncommitted run-off. We distinguish the following elements in the evolution towards closure: (a) decreasing farm income; (b) increase in irrigated area and factor intensification as a response to this; (c) expansion of irrigation to formerly rainfed crops (i. e. olive groves); (d) new demand from other sectors; (e) increase in environmental flow control; (f) reduction in water allocation; (g) increase in water costs; (h) introduction of water saving technologies; (i) mainstream adoption of deficit irrigation; and (j) administrative basin closure. The push towards water saving and efficiency increases is now leading to the emergence of two new driving forces: (k) increase in water productivity and (l) more inelastic irrigation demand, which, paradoxically, could lead to higher vulnerability to extreme events, as well as a further increase in water consumption. Although most of the drivers, pressures and processes are common among other closed basins around the world, three factors make the Guadalquivir distinct: the cultivation of high-value irrigated Mediterranean crops, a predominance of deficit irrigation and a large investment in water saving technologies.
