Free-flowing rivers

Free-flowing rivers (FFRs) are the freshwater equivalent of wilderness areas and they support many of the most diverse, complex and dynamic ecosystems globally, providing important societal and economic services. FFRs can be defined as rivers where ecosystem functions and services are largely unaffected by changes to the fluvial connectivity, allowing unobstructed movement and exchange of water, energy, material and species within the river system and with surrounding landscapes.

Researchers have assessed the connectivity status of 12 million kilometers of rivers, and determined that only one-third of very long rivers remain free-flowing. Of these free-flowing rivers, 260,000 kilometers are at risk when considering proposed future hydropower projects. The HydroSHEDS river network provides the underpinning hydrographic data to support the identification of free-flowing and at-risk rivers. The goal of these assessments is to aid in strategic conservation planning to safeguard the remaining free-flowing rivers or restore those that have already been degraded.

Map of free-flowing river status. Rivers in blue are free-flowing, rivers in green have good connectivity status, and rivers in red are heavily impacted by connectivity loss. Rivers in yellow are currently free-flowing but risk losing connectivity due to planned hydropower development.

Learn more

Read the Nature paper: Mapping the world's free-flowing rivers (Grill et al., 2019) (Full-text access here)

Read the follow-up paper: Navigating trade-offs between dams and river conservation (Thieme et al., 2021) (Open access)

Visit the WWF's free-flowing rivers initiative site.

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