Fragmentation by Dams impact rivers and aquatic ecosystems

Dams are one of the main reasons for the decline of rivers

soon Photos “Large and small dams” and “wears”

The poor condition of our rivers can be attributed primarily to the unrestrained construction of dams for the purposes of energy production and irrigation, the policy of intensive agricultural and in part by a misplaced over-dimensioning of channelling for transport and a misplaced understanding of flood protection.

The basis of the ERN projects and campaigns places particular emphasis on the issue of the high concentration of dams for hydro power plants (read our page on Hydropower) on the majority of river courses and the prevention of ecological free-passage for fish and debris. Reducing the overall number barriers of all types or their drastic modification can lead to very fast and significant regenerating of the dynamics of a river, stimulation of the self-cleaning process and to an increase in biodiversity

Map from : AMBER, Belletti et al 2020. Nature. 588, 436-441
Pan-European Atlas of Obstacles in Rivers,630,000 obstacles identified and 1 million estimated, of which 100,000 are obsolete or unused, AMBER 2020

.
Map from :  Hydropower pressure on European Rivers : The story in numbers, Euronatur,Riverwatch, WWF, Geota, 2019

Dams have severe negative environmental and social impacts

> Interruption of the ecological continuity,

  • Blocking the Fishmigration
  • Loss of  Biodiversity
  • Lack of sediment downstream of dams
  • Deepening of the river bed, ground water level sinks
  • Increasing flood impact downstream
  • Disconnection of lateral water body

Example, the Rhine River : No more salmon wild salmon, Speed of water flow between Basel and Karlsruhe has doubled , Water retention is reduced

> Increasing Erosion of the coastline

Examples : Rhone rivers, heavy damned: Loss of 2 – 10 m land / year along the Camargue coastline (Rhone Delta), Saint Marie de la Mere will become  a Island (Lack sediments – rising  sea level). Same issues on the Ebro delta.

> Increasing  water temperature  in the reservoirs an the rivers

  • eutrophication impacting water quality and ecosystems

> Displacing Millions of humans worldwide

Actualités

Dams worldwide

IN EUROPE, MOST OF THE DAMS ARE USED FOR THE PRODUCTION OF >HYDROPOWER ! Renewable but not realy green !