Free-flowing rivers (FFR) are defined as rivers in which ecosystem functions and services are largely unaffected by changes in river connectivity, allowing the unhindered movement and exchange of water, energy, materials, and species within the river system and with surrounding landscapes. River connectivity includes various components such as river channel, floodplains, groundwater, and atmospheric water. River restoration projects employing Nature-based solutions often aim to re-establish river connectivity.

Source: Grill, G., Lehner, B., Thieme, M. et al. Mapping the world’s free-flowing rivers. Nature 569, 215–221 (2019). https://doi.org/10.1038/s41586-019-1111-9