As sea levels rise, many coastal cities around the world face an even more urgent threat: they’re sinking into the ocean.
This alarming phenomenon, known as land subsidence, is primarily driven by human activities like excessive groundwater extraction and the construction of heavy infrastructure.
In some cases, cities are sinking faster than sea levels are rising, putting millions of residents, homes, and businesses at risk.
In this article, we’ll explore the 10 fastest-sinking coastal cities, based on satellite data and scientific research and reveal the causes behind their rapid decline. Understanding these trends is essential for future urban planning and climate resilience.
1. Tianjin, China
Tianjin, China, holds the top spot on this list of fastest-sinking coastal cities, with a Peak Velocity of 43 mm per year.
Its Median Velocity is 6 mm annually, indicating that while some areas experience rapid sinking, the average rate across the city is lower.
The ranking methodology prioritized peak velocity to identify the most severe subsidence. Experts specifically point to geothermal well drilling, which commenced in 1979, as a primary cause for Tianjin’s aggressive subsidence, with over 70 wells drilled since.
This aligns with the broader understanding that human activities, such as constructing excessively heavy buildings and extracting too much groundwater, are the main culprits behind sinking land.
Encouragingly, data suggests that Tianjin’s subsidence rate is declining due to local efforts.
2. Ho Chi Minh City, Vietnam
Ho Chi Minh City, Vietnam, ranks as the second fastest-sinking coastal city, exhibiting a Peak Velocity of 43 mm per year.
Its Median Velocity is 16 mm annually, which is significantly higher than many other cities on the list, suggesting widespread rapid sinking.
Researchers, using satellite radar, identified this city among the 10 at especially high risk from among the 48 largest coastal cities globally.
The phenomenon, known as land subsidence, is largely driven by human actions, including the weight of massive urban structures and the excessive removal of groundwater.
Any rate of land subsidence is detrimental, posing a serious threat to the population and infrastructure.
3. Chittagong, Bangladesh
Chittagong, Bangladesh, is identified as the third fastest-sinking coastal city, with a Peak Velocity of 37 mm per year.
The city’s Median Velocity stands at 12 mm annually, indicating a considerable rate of sinking across a broader area.
This data was part of a study featured by Nature Sustainability, which leveraged satellite radar to assess land subsidence in major coastal urban centers.
The primary drivers of sinking land are almost entirely human-related, including the burden of heavy buildings on the ground and the over-extraction of groundwater. Such subsidence represents a significant and ongoing threat to urban stability and safety.
4. Yangon, Myanmar
Yangon, Myanmar, ranks fourth among the fastest-sinking coastal cities, recording a Peak Velocity of 31 mm per year.
Its Median Velocity is 4 mm annually, which, while lower than its peak, still contributes to the overall subsidence.
The study that produced this ranking selected cities based on their high risk from among the world’s 48 largest coastal cities.
The term for this phenomenon is land subsidence, and in the context of these cities, it is predominantly caused by human activities.
These causes typically involve the weight of infrastructure and the depletion of subsurface water resources through excessive groundwater extraction. Such rates of sinking pose serious long-term challenges to urban development and resilience.
5. Jakarta, Indonesia
Jakarta, Indonesia, is the fifth fastest-sinking coastal city, with a Peak Velocity of 26 mm per year. The city’s Median Velocity is 5 mm annually, contributing to its overall subsidence.
This assessment was conducted by researchers who used satellite radar to measure sinking rates, focusing on cities most at risk globally.
Land subsidence is a critical issue that, for the cities on this list, is primarily linked to human actions.
The main culprits are identified as the immense weight of urban development and the over-extraction of groundwater, which destabilizes the underlying ground. Any level of land subsidence is concerning and presents significant challenges.
6. Ahmedabad, India
Ahmedabad, India, holds the sixth position on the list of fastest-sinking coastal cities, with a Peak Velocity of 23 mm per year.
Its Median Velocity is 5 mm annually, signifying ongoing subsidence across the urban landscape. The data for this ranking was compiled by Mindfully American, drawing from a study published in Nature Sustainability that utilized satellite radar.
The core issue of sinking land is largely attributed to human activities rather than natural climate patterns.
These include the strain placed on the ground by heavy urban constructions and the substantial extraction of groundwater from beneath the city. Even at slower rates, land subsidence poses a considerable long-term threat.
7. Istanbul, Turkey
Istanbul, Turkey, is the seventh city on this list of rapidly sinking coastal urban areas, showing a Peak Velocity of 19 mm per year. Its Median Velocity is 6 mm annually, reflecting a consistent, albeit varied, rate of subsidence.
The study, which selected 10 high-risk cities from the 48 largest coastal cities worldwide, highlights Istanbul’s vulnerability. The primary causes of land subsidence are overwhelmingly human-driven.
These key factors include the immense weight exerted by urban infrastructure on the ground and the unsustainable removal of groundwater. Such rates of sinking pose considerable risks to the city’s foundation and its inhabitants.
8. Houston, United States
Houston, United States, is the only American city on this list of the world’s fastest-sinking coastal cities, with a Peak Velocity of 17 mm per year.
Its Median Velocity is 3 mm annually, underscoring a continuous rate of sinking. While Houston is the only U.S. city featured, many others in the U.S. also experience land subsidence issues.
According to the United States Geological Survey (USGS), excessive removal of subsurface water is a common cause of land subsidence in the U.S.
The issue of sinking land across the globe is predominantly due to human actions, such as heavy construction and groundwater extraction. However, solutions like managed aquifer recharge exist.
9. Lagos, Nigeria
Lagos, Nigeria, is identified as the ninth fastest-sinking coastal city, recording a Peak Velocity of 17 mm per year.
Its Median Velocity is 2 mm annually, contributing to its overall land subsidence. This ranking emerged from a study that employed satellite radar to analyze the sinking rates of major coastal cities globally.
The phenomenon of sinking land is primarily a result of human activities rather than natural climate cycles.
The main contributing factors include the significant weight of buildings and the extensive extraction of groundwater, both of which compromise the ground’s stability.
Any degree of land subsidence is considered problematic, presenting ongoing challenges for urban resilience.
10. Manila, Philippines
Manila, Philippines, completes this list as the tenth fastest-sinking coastal city, showing a Peak Velocity of 17 mm per year.
The city’s Median Velocity is 2 mm annually, indicating a sustained, albeit varying, rate of land subsidence. The research behind this list focused on identifying cities at particularly high risk from among the world’s largest coastal metropolises.
The sinking of land is largely attributed to human causes. These primary culprits include the enormous weight of urban infrastructure on the ground and the over-extraction of groundwater, which depletes the subsurface support.
This ongoing subsidence poses a significant threat to the city’s long-term stability and its inhabitants.
Alicia Richards