Half the World's Reservoirs Could Be Clogged up with Dirt by 2060

Why It Matters

The decline threatens water security for over 2 billion people and jeopardises a quarter of irrigated farmland, prompting urgent investment in sediment management.

Key Takeaways

• Global reservoirs lose >7% capacity per decade to sediment.
• Over 36 km³ water lost annually, equal to Three Gorges Reservoir.
• By 2060, >50% of reservoirs become functionally dead worldwide.
• Australia and Spain face highest risk, >85% and 75% loss.
• Mitigation could cost $100 billion, needing dredging, reforestation, tunnels.

Pulse Analysis

Sediment accumulation in dams is emerging as a silent crisis that compounds existing water‑stress challenges. As climate change intensifies rainfall and runoff, more silt, sand and gravel are trapped behind barriers, eroding storage capacity at an alarming 7% per decade. This loss translates to roughly 36 cubic kilometres of water each year—an amount comparable to the Three Gorges Reservoir—directly affecting the water supply of over 2 billion people and the productivity of a quarter of the world’s irrigated land.

The new study, led by Kai Liu of the Chinese Academy of Sciences, leveraged machine‑learning models on satellite imagery to assess half‑a‑million reservoirs worldwide. Its findings reveal stark regional disparities: arid zones such as Namibia and Western Australia face near‑total loss, while Australia and Spain could see 85% and 75% of their dams become functionally dead by 2060. These “functionally dead” reservoirs, defined as being more than half filled with sediment, pose safety risks and diminish downstream ecosystem health, raising concerns for infrastructure investors and policymakers alike.

Addressing the sediment dilemma will require a mix of ecological and engineering solutions. Upstream reforestation, land‑stabilisation, and erosion control can curb sediment inflow, while costly interventions like dredging and bypass tunnels may be unavoidable for critical water assets. Estimated remediation expenses could climb to $100 billion, underscoring the need for coordinated financing and regulatory frameworks. As water scarcity tightens, integrating sediment management into broader climate‑adaptation strategies will be essential for preserving global water security.