NANJING, June 5 (Xinhua) -- A recent study has found that small reservoirs around the world are losing water storage capacity at a notable rate, which could affect billions of people facing water shortages.

According to the research published in the journal Nature Sustainability, the world's reservoirs lose, on average, 7.3 percent of their storage capacity every decade. Small reservoirs, which make up the vast majority, are the hardest hit.

The study, led by researchers from the Nanjing Institute of Geography and Limnology (NIGLAS) of the Chinese Academy of Sciences, created a detailed global database called the Global REservoir Inventory, combining satellite images, geographic data and engineering records. This database includes more than 550,000 reservoirs worldwide. Over 95 percent of them are smaller than one square kilometer -- a group often left out of previous studies.

Liu Kai, a researcher at NIGLAS, said this is the first high-resolution global assessment to fully include small reservoirs.

"Reservoirs play a key role in daily life. They provide water for farming, drinking, flood control, and electricity. But over time, soil and sand carried by rivers build up behind dams, a process called sedimentation. This buildup reduces the space available for water, making the reservoirs less useful," Liu explained.

The study also identified 16 global hotspots where sedimentation is most severe. Many of these areas are also major irrigated agricultural regions or places already facing water shortages. About one-quarter of the world's irrigated farmland -- affecting more than 2 billion people -- is in areas at high risk of sedimentation. This raises serious concerns about long-term water and food security.

Without action, the researchers warn that more than half of the world's reservoirs could see their function seriously damaged by 2060.

Song Chunqiao, another researcher at NIGLAS, stressed that reservoir sedimentation is a growing threat to water, food and energy supplies and requires more attention. He added that more sustainable ways of managing reservoirs will be essential for human well-being and for achieving global development goals. ■