🌱 Why do barriers pose a threat to water habitats?
Change in water habitats can be seen in artificial barriers in waters, such as water-storing and hydroelectric dams. They hinder species migration in the river and alter water quality, sediment and nutrient flows. These are, notably, “environmental cues that are vital for species to complete their life cycles”.[i] As hydropower dams are increasingly used to generate renewable electricity, it may be worth considering how “[i]mprovements to flow regulation, fishway design and sediment redistribution can mitigate these ecological impacts”. Moreover, “[f]uture research should support reforms to dam operations and design adaptations to balance renewable electricity development and biodiversity conservation through systematic basin-scale planning, long-term monitoring, adaptive management and involving multiple actors in decision-making”.[ii]
🌱 What biodiversity is found in river floodplains?
Aside from aquatic species, terrestrial species also rely on rivers. River floodplains are highly concentrated with diverse habitats.[iii] For example, “gravel-bed river floodplains contain over half of [western North America’s] plant diversity”, while they cover less than 3% of the area.[iv] They are, therefore, vital to various species such as bears, birds, and microbes.[v] The floodplains are grounds for food and reproduction and also increase resilience to adapt to changing environments, exacerbated by climate change. Thus, the whole river channel — including floodplain and other connected waters, such as shorelines — support a diverse network of species. These are often threatened by structural modifications “such as roads, railways, and housing”,[vi] or other engineering works such as the creation of waterways for shipping.[vii]
🌱 How many floodplains are degraded?
Unfortunately, “74% of [...] Europe’s floodplains show severe degradation”.[viii] Due to “decades of river degradation”,[ix] “only 40% of waterbodies presently achieve good ecological status and 17% of floodplain habitats achieve good conservation status”.[x] Overall, “[i]t is estimated that [global] habitat losses resulted in the decrease of 81% of monitored freshwater species populations between 1990 and 2012”.[xi]
🌱 How can the degradation of rivers be stopped?
To combat the degradation of rivers, restoration work needs to account for the natural movement of the river. In this context, reintroducing “naturalized flooding regimes”[xii] and unfragmented “free-flowing rivers”[xiii] is advised.
This post has been adapted from a newsletter written by Krisna Baghouzian and Christine Nikander. The newsletter titled “How can businesses protect rivers and their biodiversity?” was originally published in “The Just Transition Newsletter” by Palsa & Pulk.
[i] Fengzhi He et al., Hydropower impacts on riverine biodiversity (2024). https://www.nature.com/articles/s43017-024-00596-0 (20.02.2025)
[ii] Fengzhi He et al., Hydropower impacts on riverine biodiversity (2024). https://www.nature.com/articles/s43017-024-00596-0 (20.02.2025)
[iii] Fengzhi He et al., Hydropower impacts on riverine biodiversity (2024). https://www.nature.com/articles/s43017-024-00596-0 (20.02.2025)
[iv] Ric Hauer, Why river floodplains are key to preserving nature and biodiversity in the western US. https://theconversation.com/why-river-floodplains-are-key-to-preserving-nature-and-biodiversity-in-the-western-us-61839 (20.02.2025)
[v] Fengzhi He et al., Hydropower impacts on riverine biodiversity (2024). https://www.nature.com/articles/s43017-024-00596-0 (20.02.2025)
[vi] Hauer et al., Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes (2016). https://www.science.org/doi/10.1126/sciadv.1600026 (20.02.2025)
[vii] Save Polesia, The route of E40 waterway. https://savepolesia.org/the-threat/faq/ (20.02.2025)
[viii] Globevnik et al., ETC/ICM Report 5/2020: Preliminary assessment of river floodplain condition in Europe (2021). https://www.eionet.europa.eu/etcs/etc-icm/products/etc-icm-reports/preliminary-assessment-of-river-floodplain-condition-in-europe (20.02.2025)
[ix] Perosa et al., A meta-analysis of the value of ecosystem services of floodplains for the Danube River Basin (2021). https://www.sciencedirect.com/science/article/abs/pii/S0048969721011293 (20.02.2025)
[x] European Environment Agency (EEA), Floodplains: a natural system to preserve and restore (2019). https://www.eea.europa.eu/en/analysis/publications/floodplains-a-natural-system-to-preserve-and-restore, p.5 (20.02.2025)
[xi] Petersen et al., Incorporating free-flowing rivers into global biodiversity targets: Prioritization and targeted interventions to maintain ecological integrity (2022). https://onlinelibrary.wiley.com/doi/full/10.1002/aqc.3898 (20.02.2025)
[xii] Ric Hauer, Why river floodplains are key to preserving nature and biodiversity in the western US. https://theconversation.com/why-river-floodplains-are-key-to-preserving-nature-and-biodiversity-in-the-western-us-61839 (20.02.2025)
[xiii] Petersen et al., Incorporating free-flowing rivers into global biodiversity targets: Prioritization and targeted interventions to maintain ecological integrity (2022). https://onlinelibrary.wiley.com/doi/full/10.1002/aqc.3898 (20.02.2025)