Résumé
The state of Cear & aacute; has spearheaded the implementation of participatory river basin comanagement in Brazil. This study examines the Patu Dam, tracing how water allocation under comanagement was designed, adapted, and institutionalized. It shows how the watershed scale fragments in a semi-arid context, giving rise to evolving hydrosocial territories. These juxtaposed, nested, or interconnected territories shift in response to water scarcity and participatory processes that are shaped by institutions, infrastructure, historical experiences of drought, power structures, and the prevalence of the State's technical knowledge. This territorial lens highlights river basin management that differs from the conventional state- and basin-centred model.