Sediment found in the world’s largest dams poses a threat to the global water supply.
That’s according to UN research which suggests nearly 50,000 large dams worldwide could lose more than a quarter of their storage capacity by mid-century due to what they call “sedimentation”.
Silt is accumulating in reservoirs, behind a dam’s barrier, the researchers say.
Sedimentation can affect hydropower production and cause damage to dams’ mechanical components.
The United Nations University’s Institute for Water, Environment and Health stress that the loss from original global dam capacity foreseen by 2050 could drop from 6.3 trillion to 4.6 trillion cubic metres, roughly equal to the annual water use of India, China, Indonesia, France and Canada combined.
The UK, Panama, Ireland, Japan and Seychelles are predicted to experience the highest water storage losses by 2050, between 35% and 50% of their original capacities, the study shows.
Dr Duminda Perera, who co-authored the study with UNU-INWEH Director Vladimir Smakhtin and Spencer Williams of McGill University in Montreal said: “The decrease in available storage by 2050 in all countries and regions will challenge many aspects of national economies, including irrigation, power generation and water supply.
“The new dams under construction or planned will not offset storage losses to sedimentation. This paper sounds an alarm on a creeping global water challenge with potentially significant development implications.”
