Excessive buildup, seismic activity, and groundwater depletion are sinking cities worldwide, including New York, Venice, Mumbai, and Jakarta.
According to WEF, New York City’s 1.68 trillion pounds of concrete, glass, and steel are built on the city’s 777 square kilometers of land, compressing and subsiding the ground. Rising sea levels and intensifying storms bring in more floods, increasing land subsidence.
Coastal cities risk sinking more than landlocked ones, except for Mexico. Excessive water extraction from aquifers in Mexico has resulted in significant land subsidence, leading to drainage system issues and impacting historic buildings.
A 2022 study published in AGU used satellite data to measure the subsidence rates in 99 coastal cities between 2015 and 2020. 33 of the 99 cities are sinking at the same rate or faster than the rise in global sea level.
The cities with the fastest subsidence rates are in South, Southeast, and East Asia, specifically Tianjin, Semarang, and Jakarta. Maximum rates exceed 30 mm per year, or 15 times faster than the global mean sea level rise. Excessive groundwater extraction is the cause of this faster land subsidence. The study notes that land subsidence will make the city more vulnerable to flooding.
Istanbul, Lagos, Taipei, Mumbai, Auckland, and the Tampa Bay Area are other cities experiencing more than 2 mm of land subsidence yearly.
The WEF article notes that nearly half of China’s major cities are sinking more than 3 mm per year due to the weight of its infrastructure and groundwater extraction, which can impact close to 30% of its country’s urban population. By 2120, up to 25% of coastal land in China could be lower than sea levels.
The article notes that land subsidence in cities will lead to escalating hardships. It can result in significant land and water loss, infrastructure damage, and people’s displacement.
In Indonesia, the government has relocated its capital from Jakarta to the island of Borneo due to land subsidence. Stopping the land from sinking will require reevaluating water use, infrastructure use, and efforts to build resilience into urban planning and design.
What is causing the land to sink?
Apart from excessive groundwater extraction, other factors that cause the land to subside are the extraction of other underground materials like oil, natural gas, and mineral resources through fracking or mining activities. Earthquakes, soil compaction, erosion, sinkhole formation, and construction, for example, from improper foundation design, can also contribute to sinking.
Solutions to addressing land subsidence
The study published in AGU uses satellite data to monitor the rate of land subsidence in many cities around the world. Monitoring systems using satellite data and technologies to detect ground movements could provide early warnings of potential issues and drive cities to prepare and plan for the future.
Water management, such as improving drainage systems and managing stormwater, can reduce erosion and soil instability. Tracking real-time water usage and leakage in water networks can help manage groundwater extraction. Recharging aquifers with surface water or treated wastewater can also help restore groundwater supplies.
Cities can also look for alternative water supplies, such as recycling water, harvesting rainwater, desalinating, and sourcing water away from subsiding areas.
Improving water conservation awareness can promote sustainable water use and management. Policymakers and residents can work together to mitigate land subsidence.
Tackling the issue of sinking infrastructure demands a holistic approach that combines engineering solutions, environmental management, and active community involvement. With rapid urbanization and climate change effects, it is crucial to implement proactive and sustainable strategies to protect infrastructure and prevent land subsidence.
Source:
How ‘sinking cities’ can address subsidence challenges. (2024, October 24). World Economic Forum. Retrieved from https://www.weforum.org/agenda/2024/10/how-sinking-cities-can-address-subsidence-challenges/
Wu, P.-C., Wei, M. (M. ), & D’Hondt, S. (2022). Subsidence in coastal cities throughout the world observed by InSAR. Geophysical Research Letters, 49, e2022GL098477. https://doi.org/10.1029/2022GL098477
What is subsidence? (2024, July 16). National Ocean Service. Retrieved from https://oceanservice.noaa.gov/facts/subsidence.html
Land subsidence: causes, effects, real examples, prevention and monitoring. (n.d.). Detektia. Retrieved from https://detektia.com/en/land-subsidence/
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