China's Cities Are Sinking Into the Ground — And Engineers Say It Can't Be Stopped
October 15, 2026 · 20 min
In four decades China moved hundreds of millions of people into new coastal megacities and built skylines at record speed. Beneath many of those cities, the ground is now sinking. The cause is not earthquakes or bad materials. It is geology: the heaviest cities ever built sit on some of the softest soils on Earth, and water has been pumped out from under them faster than nature can replace it.
The core argument of the video is that much of this damage is permanent. Cities can slow the sinking, but they cannot win back the ground they have lost.
Built on mud
Cities like Shanghai and Guangzhou stand on hundreds of metres of waterlogged silt, sand and clay laid down by rivers. That was fine for light, low-rise traditional buildings. From the 1980s, and much faster in the 2000s, millions of tons of concrete and steel were stacked on the same soil. At the same time, polluted or scarce surface water pushed cities to drill deep wells.
Pumping the sponge dry
An aquifer works like an underground sponge, and the pressurised water in it helps hold up the ground above. When cities pumped far more than rain could recharge, that pressure dropped and the soil compacted. In clay layers the flat particles lock together for good. Even if pumping stopped and rain returned, the ground would not rise again. On the North China Plain, the loss is large enough to be measured by gravity-sensing satellites.
The weight of the city
Dense districts of 30-story towers add an enormous load. In Shanghai, friction piles reach 60 to 80 metres deep, held up by the grip of the surrounding soil rather than bedrock. Clustered together, these buildings still compress the soil far below. The ground is squeezed from both directions.
Uneven sinking breaks buildings
Even sinking is survivable. Uneven sinking, called differential settlement, is not. Concrete is strong in compression but weak in tension and shear, so a building that settles more on one side begins to crack. Typical signs include:
- hairline cracks in basement foundations
- elevator shafts falling out of alignment
- pipes snapping or reversing their slope
- warped window frames, shattered glass and, over time, a visible tilt
The view from space
Radar satellite data (InSAR) covering 82 major cities found nearly half of them experiencing moderate to severe subsidence. About 45% of the urban land studied was sinking faster than 3 mm a year, and about 16% faster than 10 mm a year. That puts hundreds of millions of people in cities that are measurably going down.
Beijing, the railways and Shanghai
- Beijing, home to over 21 million people, has parts of Chaoyang district sinking up to 11 cm a year, warping subway tunnels and buried utilities.
- High-speed rail at over 300 km/h needs millimetre precision, yet thousands of kilometres cross sinking ground. Adjustable slabs and shims help, but only up to a limit.
- Shanghai began sinking in the 1920s and dropped several metres by the 1960s. Pumping limits and artificial recharge slowed it, until the Pudong building boom added a huge new load.
Key takeaways
- Groundwater pumping and building weight are sinking China’s cities together.
- Once clay layers compact, the lost elevation is gone permanently.
- Uneven settlement, not the sinking itself, is what damages buildings and infrastructure.
- For coastal cities like Shanghai, Guangzhou and Tianjin, sinking land adds to sea-level rise.
- The problem can be managed at great cost every year, but not reversed.
More from the channel: @ChinaUnderStress