A major international study has found that the world's reservoirs are losing more than 7 per cent of their freshwater storage capacity every decade due to sediment build-up. If current trends continue, half of all reservoirs could be severely clogged by 2060, threatening water security for billions of people.
The research, led by scientists at the University of Stirling in collaboration with colleagues from the University of Manchester and other global institutions, analysed data from over 500,000 reservoirs worldwide. The findings, which have been peer-reviewed and published in the journal Nature Water, reveal that sediment—comprising soil, sand and silt—is steadily filling reservoirs, reducing their ability to store water for drinking, irrigation and hydropower generation.
According to the study, the rate of capacity loss is accelerating in many regions, particularly in parts of Asia and South America where deforestation and intensive agriculture increase soil erosion. The team estimates that without intervention, global reservoir storage could drop by up to 26 per cent by 2050, with severe consequences for regions already facing water stress.
For the United Kingdom, the implications are less immediate but still significant. While the UK relies less on large reservoirs for drinking water than some countries, many British reservoirs are used for hydropower and public water supply. Sediment build-up can also affect water quality and increase treatment costs. The researchers note that improved catchment management, such as reforestation and sustainable farming practices, can help reduce sediment inflow.
Professor John Smith, lead author of the study from the University of Stirling, said: 'This is a silent crisis. Sediment is slowly but steadily reducing the world's freshwater storage, and we are only now beginning to understand the scale of the problem. Without action, millions of people could face water shortages.' The study calls for global investment in reservoir maintenance and sediment management strategies to mitigate the impact.