Graph of the Day: Number of Global Freeflowing Rivers, pre-1900 – Present

Trends in number of global freeflowing rivers greater than 1,000km in length Trends from pre-1900 to the present day and estimated to 2020 (line), in comparison with the number of rivers dammed over time (bars). WWF, 2006 The rapid development of water management infrastructure – such as dams, dykes, levees, and diversion channels – have left very few rivers entirely free flowing. Of the approximately 177 rivers greater than 1,000km in length, only around a third remain free flowing and without dams on their main channel (WWF, 2006a). While clearly this infrastructure provides benefits at one level, such as hydropower or irrigation, there is often a hidden cost to aquatic ecosystems and the wider ecosystem services that they provide. In order to sustain the wealth of natural processes provided by freshwater ecosystems – such as sediment transport and nutrient delivery, which are vital to farmers in floodplains and deltas; migratory connectivity, vital to inland fisheries; and flood storage, vital to downstream cities – it is imperative to appreciate the importance of free flowing rivers, and developing infrastructure with a basin-wide vision.

2012 Living Planet Report [pdf]