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Shanghai Sinks: The Invisible Threat Beneath the Megacity
10 Feb
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, 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.
While these interventions provide a crucial buffer, much of the past compaction is irreversible. Experts also caution about potential risks associated with water injection, necessitating careful monitoring of ground-level changes and underground pressure.
