Land subsidence poses serious threat to coastal cities

Rising sea levels have long been a concern for coastal cities, leading to increased storm surges and flooding during high tides. However, there’s an additional, often overlooked, factor making these cities even more susceptible to the encroaching waters: land subsidence. Scientists at the University of Rhode Island Graduate School of Oceanography, including Pei-Chin Wu, Meng (Matt) Wei, and Steven D’Hondt, in collaboration with the US Geological Survey, have conducted research revealing that land is sinking at a faster rate than sea levels are rising in numerous coastal cities worldwide.

The global projections are alarming, indicating a mean sea level rise of at least one-foot above year-2000 levels by the end of the century. This, combined with land subsidence, poses a severe threat to the resilience of coastal cities. To understand the extent of the problem, the researchers used radar images of the Earth’s surface collected from orbiting satellites to measure subsidence rates in 99 coastal cities across the globe.

The findings highlight the highly variable nature of subsidence rates within cities and from city to city. If these rates persist, many metropolises could face flooding much sooner than predicted by existing sea level rise models. Notably, cities in South, Southeast, and East Asia are experiencing the most rapid rates of subsidence. Jakarta, Indonesia, serves as a stark example, prompting the country to relocate its capital to Nusantara, approximately 800 miles away, due to the alarming sinking of Jakarta, primarily caused by groundwater extraction.

However, land subsidence is not limited to Asia. Research conducted in collaboration with Tom Parsons of the U.S. Geological Survey reveals that even the iconic New York City is not immune. The city is sinking between 1 to 4 centimeters per year, a result of a combination of glacial rebound and the immense weight of its over 1 million buildings. This subsidence exacerbates the city’s vulnerability to coastal storms, especially considering the projected sea level rise of 8 to 30 inches by 2050.

In the United States, many cities on the Atlantic coast, primarily affected by glacial rebound, are experiencing subsidence. Even if the rate seems relatively low at minus-1 millimeter per year, it is a factor that should not be ignored. Cities in the Gulf of Mexico, such as Houston and New Orleans, also face the threat of subsidence, further complicating the challenge of adapting to rising sea levels.

Governments worldwide are grappling with the complex challenge of mitigating subsidence in coastal areas, recognizing the shared global challenge of preparing for a growing flooding hazard. As researchers continue to refine their understanding, incorporating technologies like machine learning to enhance monitoring capabilities, they stress the importance of city planners, emergency managers, and decision-makers accounting for subsidence in their current plans. The urgency lies in preparing for the impacts of rising sea levels that, when combined with subsidence, present an imminent and escalating threat to the future resilience of coastal cities.

Indonesia’s capital city Jakarta sinks

As Jakarta, the current capital of Indonesia, faces the alarming issue of sinking due to land subsidence caused by factors like excessive groundwater extraction, the government has already taken a significant step by planning to relocate the capital to Nusantara, approximately 800 miles away. However, beyond this relocation, there are several alternative strategies and measures Indonesia can consider to address the challenges posed by the sinking capital:

Enforce strict regulations on groundwater extraction to prevent further subsidence. Implement sustainable groundwater management practices, including monitoring and controlling extraction rates, promoting water conservation, and encouraging the use of alternative water sources.

Develop and implement resilient infrastructure in Jakarta and other vulnerable areas. This includes constructing buildings on stilts, designing flood-resistant structures, and implementing effective drainage systems to manage excess water during heavy rains.

Introduce green infrastructure initiatives, such as creating green spaces, urban parks, and permeable surfaces, to absorb excess water and mitigate the impact of subsidence. Green roofs and permeable pavements can help in reducing surface runoff and improving overall urban resilience.

Utilize advanced technologies, including satellite-based monitoring and geospatial data analysis, to continuously monitor land subsidence. Early warning systems can provide real-time data, allowing authorities to respond promptly to subsidence-related challenges and minimize potential damages.

Integrate climate-resilient urban planning practices to address both land subsidence and sea-level rise. Plan developments with consideration for future climate scenarios, incorporating elevated structures, flood barriers, and other adaptive measures to safeguard against the impacts of sinking land and rising seas.

Promote sustainable and well-planned urban development to reduce the overall environmental impact. Encourage mixed-use developments, implement green building standards, and prioritize eco-friendly transportation options to create more resilient and sustainable urban environments.

Engage communities in understanding the challenges posed by land subsidence and involve them in adopting sustainable water usage practices. Public awareness campaigns and educational programs can help residents comprehend the importance of reducing groundwater extraction and participating in resilience-building efforts.

Collaborate with international organizations, research institutions, and other nations facing similar challenges to share knowledge, expertise, and best practices. Engaging in joint research projects and accessing global resources can contribute to innovative solutions for mitigating the impacts of sinking cities.

Support climate-resilient agricultural practices in surrounding areas to reduce the dependency on groundwater for irrigation. Promoting water-efficient farming methods and alternative water sources can alleviate pressure on groundwater resources.

Invest in innovative infrastructure solutions such as floating neighborhoods, amphibious housing, and other adaptive technologies that can thrive in environments prone to subsidence and flooding.

By adopting a comprehensive and multi-faceted approach, Indonesia can not only address the immediate challenges posed by the sinking capital but also build a sustainable and resilient foundation for future urban development in the face of climate change and environmental pressures.

Does a sinking Jakarta ring alarm for other cities in Indonesia? Absolutely, the sinking of Jakarta should indeed ring alarm bells for other cities in Indonesia. Jakarta’s situation highlights the broader issue of land subsidence, a phenomenon that can affect various coastal and low-lying areas across the country. Several factors contribute to land subsidence, including excessive groundwater extraction, urbanization, and geological conditions, making it a shared concern for many cities in Indonesia.

Here’s why other cities should be concerned:

Many cities in Indonesia share similar geological and hydrogeological conditions with Jakarta. Areas with soft soils, coupled with excessive groundwater extraction, are prone to subsidence. Cities located in coastal or delta regions may face comparable challenges.

Rapid urbanization and extensive infrastructure development, common trends in many Indonesian cities, contribute to increased land subsidence. As cities expand and demand for resources grows, the risk of subsidence intensifies, particularly if sustainable development practices are not prioritized.

Like Jakarta, several cities in Indonesia heavily depend on groundwater for various purposes, including drinking water supply and industrial needs. Over-extraction of groundwater without proper management can accelerate subsidence, impacting the stability of the land and infrastructure.

Coastal cities in Indonesia are susceptible to both land subsidence and rising sea levels due to climate change. Jakarta’s sinking is exacerbated by these factors, and other coastal cities may face a similar dual threat, necessitating comprehensive adaptation and mitigation measures.

Land subsidence poses a significant risk to critical infrastructure such as roads, bridges, and buildings. The sinking of Jakarta has already led to challenges in managing flooding and infrastructure damage. Other cities should anticipate potential impacts on their infrastructure and the economy if similar subsidence trends are observed.

The sinking of Jakarta underscores the importance of sustainable water management practices. Other cities should reassess their water extraction policies, invest in alternative water sources, and promote water conservation measures to mitigate the risk of subsidence.

Cities facing similar challenges should engage in collaborative planning and knowledge-sharing initiatives. Learning from Jakarta’s experiences and implementing best practices can help cities develop effective strategies to address subsidence while fostering sustainable urban development.

Land subsidence can have adverse effects on the environment and ecosystems. Other cities should consider the potential impact on natural habitats, water resources, and biodiversity, emphasizing the need for an integrated approach to urban development that prioritizes ecological sustainability.

In light of Jakarta’s situation, it is crucial for other cities in Indonesia to proactively assess their vulnerability to land subsidence, identify potential risk factors, and implement measures to enhance resilience. This includes adopting sustainable urban planning practices, promoting responsible groundwater management, and collaborating with experts and stakeholders to address the shared challenges associated with sinking land.

Some people ask – is Indonesia heading towards sinking below sea water. In my opinion, it is not accurate to predict that Indonesia as a whole will sink below sea level in a few decades, the sinking of Jakarta does highlight serious concerns about land subsidence, particularly in low-lying coastal areas. Jakarta, being the capital and a major urban center, is experiencing significant subsidence due to factors such as excessive groundwater extraction, urbanization, and geological conditions.

While Jakarta’s sinking is a significant concern that requires immediate attention and action, it does not necessarily imply a uniform sinking of the entire country below sea level. The situation emphasizes the need for comprehensive and proactive measures to address the localized impact of subsidence and to build resilience against the broader challenges posed by climate change and sea-level rise. Indonesia’s response will involve a combination of adaptation, mitigation, and sustainable development practices to ensure the long-term viability of its coastal areas and urban centers.

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