The EU’s biodiversity strategy for 2030 aims to restore at least 25 000 km of free-flowing rivers by 2030, by removing barriers and restoring floodplains and wetlands. The EEA briefing ‘Tracking barriers and their impacts on European river ecosystems’ provides an overview of the density of barriers in Europe’s rivers, their impacts, and how to strengthen monitoring and information about river fragmentation.
Single large barriers, such as dams, or a series of small structures alter a river’s natural flow and cause pressures on fish and other species as well as their habitats. Based on recent studies, it can be estimated that there are more than one million barriers in European rivers and that about 10 % of them are obsolete.
The importance of free-flowing rivers that allow free movement of water, sediment, fish and other organisms is increasingly recognised by EU environmental policy, in particular the Water Framework Directive and the biodiversity strategy for 2030. However, the large number of barriers on our rivers has resulted in a loss of river continuity. This briefing addresses the following questions: What is the density of barriers on rivers? What do we know about their impacts on rivers? How can we improve the European knowledge base on barriers in rivers?
The EEA has earlier published data showing that barriers in rivers constitute a significant pressure for about 20% of European surface water bodies and they are one of the main reasons for rivers failing to reach good ecological status.
According to the EEA briefing, restoration measures aim to improve river continuity in several parts of Europe. Common measures include removing barriers, helping fish to migrate and re-establishing sediment transport.
The EEA briefing states that regular updating of a European database that keeps track of new, existing and removed barriers is important to monitor progress in restoring river continuity. Moreover, these data should tell if barriers have been made passable for fish and other species or water and sediment flows.
- River continuity is key to achieving good status of European waters under the Water Framework Directive. The EU biodiversity strategy also aims to restore at least 25 000 km of free-flowing rivers by 2030 by removing barriers and restoring floodplains and wetlands.
- Recent research concludes that the number of barriers on European rivers is well over 1 million, while there are very few free-flowing rivers in the river network. The majority of barriers are small structures, and thousands of them are obsolete.
- According to the information reported for the second river basin management plans in accordance with the Water Framework Directive, barriers consititute significant pressures for about 20% of European surface water bodies. They are one of the main reasons for rivers failing to reach good ecological status.
- To monitor progress towards achieving European targets for restoring river continuity, we should improve our information base on river fragmentation. Regularly updating a European database on barriers is necessary to keep track of new, existing and removed barriers, as well as barriers made passable for migrating fauna, along with water and sediment flows.