“First of all, it is important to underline that the NRL is an absolute needed step in the right direction, also clearly confirmed from a scientific point of view. But river ecosystems are complex networks and their connectivity plays an important role. Hence, clear definitions of the central terms in the law are crucial for enabling efficient implementation,” explained IGB researcher Dr. Twan Stoffers, lead author of the study.
Develop a clear definition of free-flowing rivers, barriers, and reference areas
Developing a well-defined and parameterised definition of free-flowing rivers is critical for NRL purposes, as river conservation planning is frequently hampered by difficulties in translating broad conservation objectives into specific and measurable protection goals. Therefore, the authors recommend using a holistic approach, defining free-flowing rivers as fluvial systems in which ecosystem functions and services are not affected by any human-induced change in fluvial connectivity. This allows for the unrestricted movement and exchange of water, energy, material, and biodiversity within the river system and across surrounding landscapes. “The European Commission has formulated suitable definitions for the restoration of river connectivity, which is currently finetuned by the ECOSTAT working group. These definitions should be used and not watered down during the next steps including the implementation,” Twan Stoffers underlined.
Consider the network structure of rivers and their connectivity dimensions
A river is more than just its visible surface; it's complex in its structure, connectivity, and interaction with its environment. Firstly, rivers are connected in three ways: longitudinal (upstream and downstream), lateral (e.g., with floodplains, other backwaters, and small streams), and vertically (groundwater, and the atmosphere). Secondly, these connections change with the river's dynamic behavior, which can expand or shrink the space it occupies depending on changes in river discharge and flow, and is regarded as the fourth dimension of rivers (temporal connectivity).
Although useful, this 4-dimensionality model falls short of adequately representing the longitudinal dimension: rivers are not linear landscape features that simply grow in size from a source to the ocean, but rather form spatially explicit, hierarchically organised, dendritic networks that integrate a landscape. “We know that this potentially adds more complexity to the implementation planning, but it is important for the efficiency of the planned restoration activities. This network perspective should definitely be considered when designing efficient protection of their biodiversity and functioning, and that is why we also suggest including minimum river section length as a restoration target for free-flowing rivers,” explained Prof. Thomas Hein, co-senior author and scientist at BOKU.
Incorporate meta-ecosystem thinking in restoration planning
Addressing challenges 1 and 2 in NRL implementation helps define free-flowing rivers and restoration targets and incorporates the physical nature of river networks. However, to fully integrate the ecological dimension of free-flowing rivers, restoration efforts must consider the connectivity and interactions within and among aquatic systems, as well as their riparian and terrestrial environments. This requires the understanding of ecological processes across different scales and their response to river network impairment, to guide suitable restoration strategies and post-restoration monitoring targeting key drivers such as climate change, river fragmentation, and loss of critical habitats. Moreover, creating migration corridors, river-floodplain connections, and hot-spots for diverse species communities is crucial for protecting many freshwater-dependent species.
Meta-ecosystem thinking that explicitly considers connectivity and interactions within and among riverscapes should guide European river restoration efforts. This fosters large-scale planning and collaboration, preferably at the landscape and catchment scale. “Such restoration efforts may enhance resilience to extreme drought and flooding events which are anticipated to become more frequent due to climate change,” said Thomas Hein.
Prioritise actions to maximise quantity and quality of free-flowing river networks
© David Ausserhofer/IGB
“Restoring an additional 25,000 km of free-flowing rivers by 2030 will not suffice to halt the decline of freshwater biodiversity, let alone reverse it. Due to the relatively small number of rivers to be restored, the implementation should focus on areas where restoration efforts will result in the most substantial improvements to ecological conditions, freshwater resources, and ecosystem services. In fact, it makes little sense to prioritise restoring degraded systems while still degrading near-natural or pristine systems at the same time”.
Professor Sonja Jähnig
Aligned with their recommendations for addressing the described challenges 1 to 3, the researchers recommend using a prioritisation approach that considers not only physical location, ease of restoration, and economic factors but also expected ecological outcomes. “To be clear: restoring an additional 25,000 km of free-flowing rivers by 2030 to meet the EU biodiversity target will not suffice to halt the decline of freshwater biodiversity, let alone reverse it. Due to the relatively small number of rivers to be restored, the implementation should focus on areas where restoration efforts will result in the most substantial improvements to ecological conditions, freshwater resources, and ecosystem services,” explained Prof. Sonja Jähnig, co-senior author and scientist at IGB. According to the NRL, restoration efforts should focus primarily on obsolete barriers that are no longer required for renewable energy production, inland navigation, water supply, or other uses. “This approach is only the harvest of the ‘low-hanging fruits’. In fact, it makes little sense to prioritise restoring degraded systems while still degrading near-natural or pristine systems at the same time,” Sonja Jähnig highlighted.
Enhance awareness, stakeholder participation and citizen engagement
Still, rivers are often predominantly seen as resources for specific economic interests such as extractive industries, agriculture, and infrastructure development. Additionally, freshwater processes are often hidden from the human eye and not recognised as integral parts of nature, leading to a lack of awareness among stakeholders and citizens that the biodiversity and integrity of freshwater systems is the basis for the ecosystem services they provide to people.
“Engaging stakeholders is especially important for understanding the specific human demands relevant for each river network and therefore for successful river restoration. This is why we recommend the full inclusion of all stakeholders in conservation and restoration efforts: policymakers, authorities, river managers, protection and user associations, and the general public,” said Twan Stoffers.
Consider conflict areas with other legislative frameworks
Resolving conflicts and finding territorial compromises at the riverscape level is critical for effective water management and aquatic biodiversity protection. But still, conservation and restoration efforts are often not given the same priority as competing interests, such as agricultural production or hydropower generation. The Common Agricultural Policy (CAP) or the Renewable Energy Directive (RED) and also the EU's regional infrastructure instruments such as the Cohesion Fund are conflicting with restoration goals. “A lot of experiences with the CAP have shown that quite some EU Member States prioritise short-term economic gains over preserving their natural resources and capital for future generations,” said Twan Stoffers. In general, nature conservation needs are considered to a moderate extent, whereas sectoral demands — often justified as "societal demands" – tend to be prime considerations, the scientists argue.
Furthermore, the complex legal and administrative processes involved in implementing the law at various levels, as well as coordinating actions among different Member States, add to the difficulty. “A law can only be as good as its practical implementation,” said Sonja Jähnig. “We already see that with the Water Framework Directive, aiming at reaching the good ecological status or potential of waterbodies. Despite turning into force over 20 years ago, the implementation deficit is still huge. But to give it a positive spin: The NRL could be a booster and role model for the Water Framework Directive activities, if the NRL implementation is done right,” Sonja Jähnig explained.
To manage conflicts, the authors propose using a negotiation process similar to the holistic approaches used in water-scarce regions. This includes establishing flow requirements and comprehensive water planning to ensure sustainable water use and ecosystem restoration.
Establish methods for identifying integrated connectivity across river networks
To assess restored connectivity and effectively monitor continuous restoration progress, the researchers propose an integrated monitoring framework that combines established knowledge and tools (such as those used in assessments compliant with the WFD and Nature Directives) with innovative tools fully considering meta-ecosystem and metacommunity dynamics at the riverscape scale. For instance, remote sensing applications and satellite imagery such as the Copernicus dataset could be used to develop and provide high-resolution habitat maps that offer functionality to monitor land use and habitat area especially where human infrastructure (levees, roads, railroads, bridges, and cities) intersects or disrupts riverscapes. At the level of biodiversity, the scientists suggest drawing on methodological advances in environmental DNA (eDNA) surveys, which now allow for riverscape biodiversity assessments. “Integrating different kinds of data in a monitoring approach as broad or even broader than outlined above, will undoubtedly be difficult, but we are confident that the NRL's ambitious goals deserve a no-holds-barred approach when conceptualising adequate monitoring methodologies,” said Twan Stoffers. “In general, monitoring data and reports should be public so that stakeholders of nature restoration as well as river basin managers, policymakers and Member States can access the latest results and immediately respond to threats of restoration success.”