As sea levels continue to rise due to climate change, many coastal cities around the world are sinking, putting millions of people at risk. The combined effects of climate change, land subsidence, and urbanization have made many of the world's largest and most rapidly growing cities unlivable. The risk of urban flooding has drastically increased due to the sinking of coastal cities. Humans are partly to blame for this crisis, as we have contributed to the rising sea levels through our greenhouse gas emissions.
New York City is sinking at an alarming rate of approximately 1-2 mm each year on average, with some areas of the city sinking at double this rate. The weight of the city's skyscrapers is exacerbating the sinking, which in turn is worsening the effects of sea level rise and flooding.
Jakarta, the capital of Indonesia, is one of the fastest sinking cities in the world, with almost half the city sitting below sea level.
Countries continue to invest people, assets, and infrastructure into these cities, the loss potential in these areas also increases. Sinking cities must overcome substantial barriers to properly prepare for today's dynamic environmental climate. The sinking cities crisis is a looming environmental disaster that requires immediate attention and action.
These cities are a looming environmental crisis that requires immediate attention and action. Fortunately, there are ways to prevent our cities from sinking, some of them being:
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Sustainable water management: Reducing water extraction, promoting water conservation, and implementing groundwater recharge can mitigate the effects of subsidence in cities.
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Restoring water ecosystems in cities: Solutions can be permeable asphalt and soakaways, which ensure that rainfall does not end up in a city's sewage system but instead infiltrates into the ground. Bringing back existing watercourses and green spaces can contribute to re-establishing water ecosystems in cities.
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Constructing cities to prevent sinking: Protecting shorelines of coastal sinking cities is crucial to preventing the sea from taking over. Building on stilts is another way to prepare for changing water levels. Compensated foundations can reduce the stress on a city's surface, which otherwise is a consequence of heavy loading.
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Replenishing groundwater: In instances where urbanization-driven subsidence is exacerbating the impacts of sea-level rise, one of the solutions to subsidence can be replenishing the groundwater.
Bangkok, Jakarta, Metro Manila, Ho Chi Minh City, and Shanghai are some of the cities that have implemented policies to reduce subsidence. However, some scientists argue that current mitigation policies are not enough.
Tokyo is an example of a city that has developed sophisticated techniques for measuring, monitoring, and combating land subsidence. Groundwater regulations were implemented in the early 1960s and subsidence came to a halt after a decade.
Managed aquifer recharge, also known as water banking, is a solution that some cities are implementing to replenish groundwater. This approach has been successful in some cities, but it is not feasible for communities that need to supply water to a large number of residents.
While some cities have implemented successful solutions to mitigate subsidence, many other large cities, particularly in developing nations, have no record of their subsidence, which is far from under control. Governments, businesses, and individuals must work together to reduce greenhouse gas emissions, invest in sustainable infrastructure, and adapt to the changing landscape to prevent the cities from sinking.
Editor: Ms.Fahima Afrin