Facts and Figures

Some ecosystems can disappear when rivers are regulated or impounded

  • Freshwater ecosystems include lakes, rivers, ponds, streams, groundwater, springs, cave waters, floodplains, as well as bogs, marshes and swamps, which are traditionally grouped as inland wetlands.
  • Humans have settled near water bodies for millennia. Urban growth and industrial development have pushed cities to look increasingly farther for the water they need, often taking water from, and perhaps hurting, other users – like nature.
  • Modifications made for water-related development (dams, irrigation schemes, urban extension, aquaculture and the like) have major consequences for the key ecological components or processes of rivers, lakes, floodplains and groundwater-fed wetlands.
  • As of 2000 there were more than 50,000 large dams in operation. Some 589 large dams were built in Asia from 1999 to 2001. Of the world’s 292 largest river systems in 2005 (accounting for 60% of the world’s runoff), more than a third (105) were considered to be strongly affected by fragmentation, and 68 moderately affected. 
  • Some ecosystems disappear when rivers are regulated or impounded because of the altered flow and new barriers to the movement of migratory species. 

Related themes: Ecosystems; Human Settlements

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