NASA Confirms Three Gorges Dam Influences Earth's Rotation

Research validated by NASA has confirmed that the massive water retention of the Three Gorges Dam in China's Hubei Province imparts a quantifiable influence on the Earth's rotational dynamics. This effect is governed by the conservation of angular momentum, similar to how a spinning object changes speed when its mass distribution shifts. When fully charged, the dam's reservoir holds approximately 40 cubic kilometers, or 40 billion tons, of water concentrated in a fixed geographical location.

Geophysicist Dr. Benjamin Fong Chao of the NASA Goddard Space Flight Center quantified this impact in 2005. His analysis suggested that the relocation of this water mass could lengthen the Earth's day by an increment of about 0.06 microseconds. The mass shift is also calculated to cause a corresponding displacement in the Earth's rotational axis, estimated at approximately 2 centimeters. While these alterations are imperceptible in daily human experience, they hold significance for high-precision geophysical and astrophysical measurements.

The Three Gorges Dam is a cornerstone of China's energy infrastructure, currently supplying around 3% of the nation's total energy needs, an output exceeding the combined capacity of 15 standard nuclear power plants. The structure spans the Yangtze River, measuring 2,335 meters in width and 185 meters in height above sea level, with a construction cost estimated between $20.4 billion and $37 billion over its 17-year build period. This demonstrates how large-scale anthropogenic construction can affect planetary mechanics.

This human impact on rotation is contrasted with the effects of mass loss from processes like the melting of polar ice sheets, which shifts planetary mass toward the equator, lengthening the day at the fastest recorded pace of the last century, approximately 1.33 milliseconds per 100 years. The dam's influence, while minuscule compared to natural forces like the Moon's tidal friction, which lengthens the day by about two milliseconds per century, serves as a critical data point. For context, the 2004 Sumatran earthquake shifted enough mass to shorten the day by 2.68 microseconds, an effect significantly larger than the dam's contribution.

The cumulative effect of thousands of global dams has been suggested to have shifted the Earth's rotational axis by nearly a meter over recent decades, according to research published in Geophysical Research Letters. The sheer scale of the Three Gorges Dam, holding up to 40 billion cubic meters of water, makes its specific contribution a focus for understanding the interconnectedness of massive human infrastructure and planetary geophysical stability. Furthermore, the reservoir's weight has been linked to increased seismic activity in western Sichuan, with over 30,000 small earthquakes recorded between 2000 and 2024 due to reservoir-induced seismicity.