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Free Flowing Rivers, Historical, Baseline, Global (v1.0)


Global rivers are represented in this dataset. A free flowing river is defined as one which is not affected by human development with regards to its flow and connectivity. Free flowing rivers are vital for biodiversity because they create diverse habitats that support a wide range of species. Their natural flow regimes deliver essential nutrients and sediments, supporting aquatic life and replenishing wetlands, which are crucial for many organisms, including migratory birds. These dynamic ecosystems maintain ecological balance, facilitating the life cycles of many aquatic species.

biodiversity, water, freshwater, ecosystems, nature, river
Temporal Extent:
2000-02-11 to 2000-02-22
500 meters
Product Version:

Technical Description

This dataset provides polylines that represent river networks, derived from and consistent with other HydroSHEDS datasets. These data are based on 15 arc-seconds (approx. 500 m at the equator) resolution raster data. 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.

Rivers were defined to start at every pixel where the accumulated upstream catchment area exceeds 10 km^2, or where the long-term average natural discharge exceeds 100 liters per second, resulting in a total global river length of 35.9 million kilometers (excluding Antarctica). Rivers were broken into line segments at every confluence, here termed ‘river reaches’, representing the smallest unit of the river network and creating 8,477,883 million individual river reaches with an average reach length of 4.2 km. Each river reach is linked to an area of its contributing hydrological sub-catchment, here termed ‘reach catchment’, with an average extent of ~12 km^2.

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.

NOTE: This is a derived dataset of the raw FFR data, selecting only free flowing rivers (CSI_FF1 == 1), and creating polygonal distance buffers around the river lines. Due to technical limitations, these have not been dissolved/flattened, so some locations will have multiple overlapping polygons. TAKE THE MAXIMUM VALUE WHEN WORKING WITH THIS DATA!.

This dataset contains the following fields:

  • river_proximity_class : This is a categorical value representing the proximity of the point location to the nearest free flowing river. Locations are binned into three separate classes: 1 (1.0 - 5.0 km), 2 (0.5 - 1.0 km), and 3 (<5.0 km). A null value indicates that the location is not within 5 km of a free flowing river.