Free-flowing rivers are essential ecosystems providing vital services. Yet, ever-increasing human population causing global change, significantly alters these ecosystems. Anthropogenic water regulating structures, such as pumps and shipping locks, block fish when undertaking their critical migratory journeys. In the Northern Atlantic, the population size of diadromous fish species, i.e. species that migrate between freshwater and marine realms to complete their life cycle, declined by at least 90% since the end of the 19th century. Despite legislation and management efforts to restore diadromous fish, the desired results are still to be reached. This project takes action on the urgent need to include data and knowledge-driven measures into water management in Flanders for diadromous species restoration. For this purpose, a model-based water management tool will be developed which estimates when fish want to migrate across a barrier and which conditions must be met to do so safely. At its core, the tool consists of an individual-based model. By making use of several telemetry datasets of the flagship species the European eel (Anguilla anguilla), downstream migration behavior in typical Flemish landscapes is studied. In this way, the effect of barriers in both polder areas and canalized rivers, typical water systems in Flanders, is investigated at both individual and population level.