Why is Shanghai sinking?

Shanghai is sinking due to excessive groundwater pumping and the natural compaction of its soft, compressible soil, exacerbated by the weight of urban development.

How are engineers slowing Shanghai's sinking?

Engineers are slowing Shanghai's subsidence by reducing groundwater extraction, shifting water usage to deeper aquifers, and injecting treated river water into the subsurface.

What are the risks of Shanghai sinking?

Sinking exacerbates flood risks, threatens infrastructure like roads and subways, and increases the cost of flood defenses, especially with rising sea levels.

Home / Environment / Shanghai Sinks: The Invisible Threat Beneath the Megacity

Shanghai Sinks: The Invisible Threat Beneath the Megacity

10 Feb

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Summary

Shanghai is sinking due to historical groundwater over-extraction.
Engineers now inject water to slow subsidence rates significantly.
Subsidence exacerbates flood risks and infrastructure damage.

Shanghai Sinks: The Invisible Threat Beneath the Megacity

Shanghai, a major coastal megacity, has been sinking for decades due to extensive groundwater extraction and its location on compressible soil. Historical data indicates a subsidence of over two meters in central districts since the early 20th century.

This land subsidence increases the city's vulnerability to flooding and sea-level rise, posing significant risks to its infrastructure. The weight of urban development also contributes to the sinking ground.

In response, authorities have implemented strategies to slow subsidence, including reduced groundwater pumping and aquifer recharge with treated river water. These actions have significantly decreased the rate of sinking from over 10-15 centimeters annually to about one centimeter per year.