I know you probably don't want to read another blog discussing the detrimental effects of climate change yet again, but the reality is that we cannot afford to ignore its impact on our planet. Among the many threats posed by climate change, one of the most alarming is the rising sea levels.
Rescuers evacuate residents from their flooded homes in Bekasi in February 2021, as heavy rain inundated the city on the outskirts of Jakarta. (Photo by Rezas/AFP via Getty Images)
The implications of such an event would be catastrophic, resulting in the loss of critical infrastructure, cultural landmarks, and homes for millions of people. In this article, we will take a closer look at three cities in Asia that are particularly vulnerable to this impending threat and explore how they plan to prevent it:
Ho Chi Minh City, Vietnam
Jakarta, Indonesia is one of the fastest-sinking cities in the world, sinking at a rate of up to 25 cm per year due to a combination of natural and human factors. The city is also facing the threat of rising sea levels and severe flooding. One major influence on Jakarta's sinking infrastructure is the land. It is built on swampy land and is heavily reliant on groundwater for its water supply. Over the years, the excessive extraction of groundwater has caused the land to sink.
Jakarta has experienced rapid population growth and urbanization over the past few decades too, which has led to the construction of large buildings and infrastructure projects. The weight of these structures on the already sinking land has further accelerated the sinking of the city.
Deforestation in the surrounding areas of Jakarta has led to soil erosion, which has caused sediment to be deposited in the city’s waterways. This sediment reduces the capacity of rivers and canals to hold water and increases the risk of flooding.
To address these issues, the Indonesian government announced in 2019 that it would move the capital city Jakarta, a megacity of 10.5 million, to a newly constructed city on the island of Borneo, 2,000 km (1,250 mi) away mainly because Jakarta is sinking. The new capital will be built on the island of Borneo, specifically in the provinces of East Kalimantan and North Kalimantan. The government hopes that the relocation will help to alleviate the problems caused by Jakarta’s sinking, as well as redistribute development and economic growth across different parts of the country.
The move to a new capital also presents an opportunity for the Indonesian government to design and build a city from scratch, incorporating modern infrastructure and sustainable technologies to reduce environmental impacts. The project is expected to take several years to complete, with estimates suggesting that the new capital could be ready by 2024 or 2025. However, the move has been met with some criticism, as some experts argue that it may not solve the underlying issues of climate change and overpopulation that have led to Jakarta’s sinking in the first place.
Ho Chi Minh City
Ho Chi Minh City, also know wn as Saigon, is a bustling metropolis located in southern Vietnam. Unfortunately, it is also one of the cities that are at risk of sinking due to several factors. The city’s location in an area of land subsidence, caused by extensive groundwater extraction, along with high tides, heavy rains, and overflow in the Saigon and Dong Nai rivers, makes it particularly vulnerable. Almost 45% of the city sits less than one meter above sea level, leading to recurrent floods. Unfortunately, housing developments have replaced vital tide-draining swamps that once protected these flood-prone areas, resulting in record-breaking river tides. These floods not only cause millions of dollars in damage but also put hundreds of thousands of people’s lives at risk.
In the face of global temperature rise, sea levels are expected to increase by over one meter by 2100. As a result, almost 20% of Ho Chi Minh City’s area will be inundated, which will displace almost 7 million people. The majority of those affected will live in the Can Gio coastal district, according to Earth.Org’s sea level rise projections.
Ho Chi Minh City is taking various measures to address the issue of sinking, which is caused by subsidence. Some of the actions taken by the city include measures to manage groundwater extraction and reduce the demand for groundwater. This includes promoting the use of surface water for industrial and agricultural purposes and encouraging households to use rainwater and treated wastewater for non-drinking purposes.
The city is also working on developing a comprehensive land use plan to manage the use of land and ensure that it is sustainable. This includes zoning regulations, building codes, and the creation of green spaces and public parks to reduce the amount of concrete and asphalt in the city. The city is investing in upgrading its infrastructure by improving drainage systems, building new bridges and tunnels, and constructing new wastewater treatment facilities to reduce the amount of groundwater extraction needed.
Ho Chi Minh City has been working with international organizations, such as the World Bank and the Asian Development Bank, to share knowledge and expertise on subsidence management and identify solutions that can be implemented in the city.
Overall, Ho Chi Minh City is taking a multi-faceted approach to address the issue of sinking, recognizing that it is a complex problem that requires a combination of short-term and long-term solutions.
Thailand’s capital, Bangkok, is projected to be the world’s most vulnerable city due to rising sea levels. The city, with an average elevation of only 1.5 meters above sea level, is already experiencing the consequences of this climate change-induced phenomenon. In 2011, devastating floods claimed hundreds of lives and submerged a fifth of the city. Unfortunately, the situation is only expected to worsen. The Organisation for Economic Co-operation and Development (OECD) predicts that by 2070, five out of the 10.7 million inhabitants of Bangkok could be at risk of flooding. However, the government’s inaction is turning this forecast into a grim reality. Torrential rains exacerbate the problem, and the inadequate drainage system does little to prevent severe flooding, which can last up to two months in some cases.
The risk of sinking in Bangkok is exceptionally high, primarily caused by ocean thermal expansion and ice melting. When combined with the projected rise in extreme weather events, it is predicted that up to one-third of the Thai capital could be entirely submerged by 2050, leading to the displacement of up to 11 million people.
Bangkok is planning short-term and long-term solutions to prevent the city from completely sinking. One approach is to adopt nature-based solutions, such as gardens, green roofs, and the restoration of urban wetlands, which can absorb additional water. They are currently a concrete jungle with little permeability. Even a moderate amount of rainfall (4 mm) can inundate the city. Another approach is to build “pocket parks” in vacant plots of land, between and underneath expressways, and other empty spaces, prioritizing construction with storing stormwater in mind to reduce the city’s flooding risk. Additionally, wastewater and stormwater can become alternative and more sustainable sources of water supply for the city.
Above is a photo of one of the larger anti-flooding projects, Chulalongkorn University Centenary Park, an 11-acre green space that can hold up to a million gallons of rainwater in Bangkok
Overall, all of these cities have one thing in common and that is the need for drastic measures to be implemented for years to come to prevent further sinking. We can summarize those universal measures as:
Reduction of groundwater extraction: To address the sinking of cities caused by excessive groundwater extraction, some cities are implementing policies and regulations to reduce the pumping of groundwater. This may include the development of alternative sources of water, such as surface water or desalination.
Building resilient infrastructure: To help prevent damage from sinking ground and floods, cities are investing in resilient infrastructure that can withstand natural disasters and adapt to changing environmental conditions. This may include the construction of flood barriers, seawalls, and green infrastructure such as parks and green roofs.
Land subsidence monitoring: Many cities are implementing programs to monitor the subsidence of land and identify areas that are at high risk of sinking. This information can help inform policies and strategies to address the problem of sinking cities.
Sustainable urban planning: Cities are also adopting sustainable urban planning practices to reduce the impact of urbanization on the environment and prevent further land subsidence. This may include the promotion of green spaces, compact and mixed-use development, and the use of sustainable building materials.
Climate change adaptation: To address the threat of rising sea levels and other impacts of climate change, cities are implementing strategies to adapt to changing environmental conditions. This may include the development of early warning systems, the relocation of vulnerable communities, and the development of climate-resilient infrastructure.
These measures are important steps toward addressing the problem of sinking cities, but more work is needed to ensure that cities are sustainable and resilient in the face of changing environmental conditions.
Understanding what's happening underground requires data, which is typically gathered by geotechnical engineers through subsurface investigations. This data could be used to study changing groundwater levels, soil strength, stresses, and the impacts of construction and climate change. It's important to note that remediation and solutions require participation from both the civilian and infrastructure communities.
However, capturing this data for an entire city can be challenging and time-consuming. Using traditional 3D modeling software can also be tedious. Civils.ai is a software that could revolutionize how we approach geologic data by providing 3D models of subsurfaces. Civils.ai is creating a platform to provide access to reliable and much-needed data about underground conditions today and documenting changes over the next several decades.
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