New satellite data reveals a sobering truth: a significant portion of China’s urban landscape is sinking, placing millions at risk. The study, published in the journal Science, estimates that roughly a third of China’s urban population, approximately 270 million people, could be affected by land subsidence. This phenomenon, where the ground level settles, threatens infrastructure, increases flood risk, and exacerbates the challenges posed by rising sea levels.
The research team, comprised of scientists from Virginia Tech and the University of East Anglia, analyzed data from 82 major Chinese cities, including megacities like Shanghai and Beijing. Their findings paint a concerning picture. Nearly half (45%) of the urban land area studied is subsiding, with over 16% sinking at an alarming rate of 10 millimeters or more annually. Cities like Beijing and Tianjin are experiencing remarkably rapid subsidence, raising concerns about the stability of critical infrastructure and buildings.
Land subsidence is primarily a result of human activities, and unsustainable groundwater extraction is a significant contributor. As cities expand, their water demands escalate. Withdrawing groundwater at a rate faster than it can be naturally replenished lowers the water table, causing the ground above to compact and sink. Moreover, the sheer weight of buildings and urban infrastructure can also contribute to subsidence in certain areas.
The consequences of sinking cities are far-reaching. Subsidence damages roads, bridges, and other infrastructure. Cracks can appear in buildings, jeopardizing their structural integrity. Coastal cities, already vulnerable to rising sea levels, face an even more significant threat. Subsidence pushes more land below sea level, increasing the risk of flooding during high tides and storms.
The study also looked ahead, combining subsidence data with rising sea-level projections. The results were unsettling. China’s urban area below sea level could triple by 2120, potentially impacting 55 to 128 million people. This scenario underscores the urgency of addressing land subsidence and highlights the need for adaptation strategies to protect coastal populations.
The situation in China is expected. Land subsidence is a global phenomenon affecting many coastal cities around the world. The research team emphasizes recognizing subsidence as a severe urban hazard. These risks can be mitigated by employing more sustainable water management practices and implementing stricter groundwater extraction regulations.
The findings of this study serve as a wake-up call. China’s sinking cities present a complex challenge but are manageable. By investing in sustainable practices, robust infrastructure, and innovative adaptation strategies, China can safeguard its urban populations and ensure their future prosperity.