The world's dams could lose a quarter of their storage capacity by 2050
After build-ups of sediment, eroding global water and energy security
A UN study looked at data from more than 47,000 dams in 150 countries
and said 16% of original capacity had already been lost
Silt accumulates in reservoirs when natural water flow is disrupted
It can:
- Cause damage to hydroelectric turbines and cut power generation
- Make upstream regions more prone to flooding
- Erode downstream habitats
Critics have long warned of the long-term social and environmental costs of giant dams
The UN says dam building worldwide had already declined significantly
China however continues to dam major rivers
Hydropower is key in its plans to cut fossil fuels and emissions