World's dams could lose a quarter of storage by 2050

STORY: Source: United Nations research

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