Ho Chi Minh City is gradually sinking

Around the base of the walls at the An Lac Ward Cultural and Sports Center (formerly of Binh Tan District), a 20 cm gap has opened between the walls and the ground on an area of around 3,000 sq.m due to subsidence.

The martial arts training rooms have uneven, bulging tiles while the badminton and basketball courts have long, clearly visible cracks.

Several of the facility's columns have horizontal fractures the width of an adult hand.

A number of households in alleys along Le Co Street some 500 meters away also have cracked floors and walls.

A local named Tran Le Do Xuan Trong said his family's three-story house has been subsiding for years. It began with the kitchen floor, causing damage that later spread to other rooms.

In the last five years his family has repeatedly raised the floors and made repairs, but the cracks in the walls have continued to lengthen, he said.

"When I built the house, I knew this area had weak soil, and so I reinforced the foundation extensively, but it is still sinking and the walls are cracking."

Despite repeated reinforcement work, the foundation of Xuan Trong’s three-storey house still has long cracks, leaving large gaps. Photo by VnExpress/Dinh Van

According to the Division for Water Resources Planning & Investigation for the South of Vietnam, between 2005 and 2017 soil in An Lac Ward subsided by 81 cm, much higher than the city’s average rate of 23 cm, and the highest in any locality.

Studies by Assoc. Prof. Dr. Le Trung Chon, director of the Research Institute for Sustainable Development at the University of Natural Resources and Environment HCMC, and colleagues show that subsidence has been occurring for more than a decade in the city and is accelerating.

Between 2006 and 2020 its average subsidence rate was 2–5 cm a year though areas with weak geology or lots of commercial buildings could experience 7–8 cm.

A 2022 study by Cheryl Tay, a PhD student at Nanyang Technological University (Singapore), and her colleagues together with U.S. and Swiss experts found that HCMC was among the fastest sinking cities in the world.

The team used satellite radar to measure subsidence rates in the 48 most populous coastal cities worldwide between 2014 and 2020.

It found that the 48 cities was sinking at an average 16.2 millimeters per year, with 44 of them sinking faster than the rate of global sea-level rise.

Cities in South and Southeast Asia, including Tianjin, Ahmedabad, and Ho Chi Minh City, were among the fastest-sinking. Parts of Tianjin and Ahmedabad have been subsiding at more than 2 cm per year, while Ho Chi Minh City has been sinking at an average rate of 1.62 cm per year. Other cities such as Chittagong, Yangon, and Jakarta have also experienced significant subsidence.

Overall, the median subsidence rate of 1.62 cm per year is nearly five times faster than the current global sea-level rise of 0.37 cm per year. This rapid sinking is primarily attributed to excessive groundwater extraction and the pressures of rapid urbanization, both of which undermine ground stability and accelerate land subsidence.

In HCMC, the researchers estimated that an additional 20 square kilometers could be submerged and flooded if the current subsidence rate continues until 2030.

A high density of skyscrapers in areas with weak soil has hastened the subsidence.

In 2019, Climate Central, a U.S. nonprofit news organization that analyzes and reports on climate science, warned that most of southern Vietnam, including the Mekong Delta and HCMC, could be under the sea by 2050. Sea levels will increase by one meter by 2100, and 18% of HCMC, and 39% of the delta could possibly submerge, it said.

Global average sea level has risen about 21–24 cm since 1880, with the rate of increase accelerating significantly in recent decades. From 2006–2015, the rate was 3.6 mm/year, more than double the rate of the 20th century. More recently, the average rate of rise from 1993 to 2023 was about 3.4 mm/year, and the rate from 2013 to 2023 was even higher at 4.3 mm/year, according to the U.S.'s National Oceanic and Atmospheric Administration.

Assoc. Prof. Dr. Le Trung Chon’s research group announced at the end of August their measurements showing subsidence rates in Ho Chi Minh City from 2015 to the present, with red areas on the map marking zones of rapid subsidence. Photo coutersy of the team

Prof. Dr. Chon notes that Ho Chi Minh City is built on a weak geological foundation, particularly young Holocene sediment layers, which are deposits from the current geological epoch that began about 11,700 years ago, that are highly prone to compression.

Excessive groundwater extraction is cited by both research groups led by Cheryl Tay and Chon as the main reason, reducing soil pore pressure and causing compaction.

Rapid urbanization, with many new buildings adding static loads to weak soil along with traffic loads, further exacerbates the phenomenon.

The worst affected are former Districts 7 and Nha Be on the southern gateway and along the Saigon River, including the Thanh Da Peninsula, Hiep Binh Phuoc and Thao Dien in the east.

Chon said the city should compulsorily factor in subsidence data in all planning, design and maintenance.

But because subsidence results from natural phenomena and human activity, it could not be completely eliminated and must be "actively managed" using data-driven science, he said.

As an immediate solution, experts recommend creating a detailed five- to 10-year subsidence forecasting system so that authorities can adjust infrastructure planning and flood prevention accordingly.

Chon said: "For example, if the former District 7 area is 1.5 m high but subsides at an average of 5 cm a year, in just 10 years the elevation will drop to one meter. This information is enough to change engineering calculations and construction costs."

Many cities like Beijing and Tokyo have used subsidence maps to guide construction permits, predict soil stability and reduce construction risks and possible economic losses, he said.

Integrating this data into planning would also help HCMC manage infrastructure, adapt to climate change and develop urban areas based on the "living with nature" principle, he said.

Associate Professor Ho Long Phi, a former director of the Water and Climate Change Management Center at the Vietnam National University, HCMC, said besides addressing immediate consequences, the city also needs long-term solutions to adapt.

It should strengthen flood control systems such as dikes, river embankments, tide gates, and pumping stations to manage water during the rainy season and high tides.

Creating a network of retention ponds and clearing canals would help store and distribute water more evenly, reducing flood risks, he said.

Over the long term he called for completing ongoing projects, particularly the nearly VND10 trillion tide-control project, which has stalled for years due to legal and land compensation issues despite being over 90% completed.

Originally planned for completion in two years after kicking off in 2016, it is meant to control tidal flooding and respond to climate change across 570 sq.km, benefiting 6.5 million people living along the Saigon River and elsewhere in the city.

Once operational, it will be key to controlling floods in the city center and southern areas, which are lower and have weaker soil than other places.

Flooding on Quoc Huong Street in Thao Dien Ward, Ho Chi Minh City, on Oct. 8, 2025. Photo by VnExpress/Thanh Tung

Earlier, recognizing the increasing complexity of climate change and flooding, HCMC’s master development plan for until 2040 identified an approach that maximizes existing infrastructure and adds new structures to form three layers of flood control: protection, adaptation and damage mitigation.

The protection layer focuses on hard infrastructure such as dikes, embankments, roads, tide gates, and flood-control corridors to manage high tides, sea-level rise and runoff.

The adaptation layer aims to build systems of retention ponds to store overflow water within dike and embankment systems. This network includes open and underground ponds, canals and parks, as long as water can be captured to reduce concentration in flood-prone areas.

The damage mitigation layer combines hard and soft infrastructure solutions, such as raising main roads to create flood zones, supporting rescue operations in extreme events and setting up early warning and evacuation systems.

Besides, the city will build elevations to harmonize with existing residential areas and new developments, ensuring optimal natural drainage, according to the master plan.

Elevation requirements are divided into three drainage zones: 2.6–3.8 m outside protective dikes and embankments, 2–2.5 m within protective zones and 30–40 cm above current levels in existing urban areas, gradually reaching 2–2.5 m according to zone-specific regulations.