Reservoirs worldwide are losing freshwater storage capacity at an alarming rate, with sediment accumulation reducing water access for billions of people. A new analysis of over 500,000 reservoirs reveals that the world loses more than 7 percent of its freshwater storage capacity each decade to sediment buildup, according to research reported by New Scientist.
At this trajectory, roughly half of the world's reservoirs could become significantly clogged with sediment by 2060. The problem stems from erosion in watersheds upstream of dams. Rivers carry soil and rock particles downstream, where the particles settle behind dam structures instead of flowing to the ocean. Over time, this accumulation reduces the volume of water that reservoirs can hold.
The consequences ripple across agriculture, hydroelectric power generation, and drinking water supplies. Reservoirs provide irrigation for roughly 15 percent of global croplands and supply drinking water to approximately 4 billion people. As storage capacity declines, communities face reduced water availability during dry seasons and droughts, while hydropower facilities generate less electricity from their infrastructure.
The sediment problem varies geographically. Mountain regions and areas with high rainfall experience faster erosion rates, sending more material into reservoirs. Monsoon regions, the Himalayas, and parts of the Andes face particularly acute challenges. Human land use intensifies the problem. Deforestation, agriculture, and construction strip vegetation that would otherwise stabilize soil and reduce erosion.
Solutions exist but require sustained investment. Dam operators can periodically drain reservoirs to flush out sediment, though this wastes water and disrupts ecosystems. Watershed management practices like reforestation and erosion control reduce sediment entering reservoirs upstream. Some regions are exploring sediment extraction technologies, though these remain expensive.
The analysis underscores how infrastructure built decades ago operates under changing environmental conditions. Many reservoirs were