Ho Chi Minh City’s latest flooding is not simply a story of heavy rain meeting high tide. It is a warning about what happens when climate change collides with rapid urbanisation, sinking land and infrastructure designed for a much smaller city. Floodwater that residents have learned to tolerate is becoming harder to drain, more disruptive to daily life and more difficult for authorities to manage.
Forecasters warned on September 27 that high tides could combine with heavy rain to raise the risk of flooding in the Vietnamese commercial capital. When the rain and tide converged on the evening of September 30, the Saigon River and smaller waterways spilled onto roads. Diners continued eating as water reached their feet, vendors sheltered under plastic raincoats and residents in ponchos moved through flooded streets to buy essential goods.
That apparent normality is central to understanding the city’s vulnerability. Flooding has become familiar in low-lying neighbourhoods, but familiarity does not make it harmless. Nguyen Ngoc Thuong, who runs a small eatery, told The Associated Press that water can reach knee height during high tides or heavy rain and can take more than two hours to recede. Some customers continue to walk through the water to reach her business.
For households, small shops and street vendors, these are not only moments of inconvenience. Floodwater can enter homes and businesses, disrupt transport, damage infrastructure, contaminate water supplies and increase public health risks. Vo Dang Thi, a 63-year-old resident, has raised the floors of her home to keep water out. Such household adaptations show how residents are compensating for a public infrastructure problem, but they also reveal the limits of individual resilience.
The city’s exposure begins with its geography. Nearly half of Ho Chi Minh City’s land is less than one metre above sea level, according to the report. That leaves a substantial share of the urban area sensitive to high tides, intense rainfall and rising seas. When these factors occur together, the drainage challenge is greater than the volume of rain alone would suggest.
Benjamin Horton, a professor of earth science at City University of Hong Kong, said climate change is amplifying flood risk by interacting with rapid urbanisation and land subsidence. Higher sea levels make it harder for rainwater to drain towards the sea. Heavier downpours can send more water into the city within a shorter period. If the land is also sinking, water accumulates faster and remains for longer.
This interaction is the city’s defining infrastructure problem. A drainage network can be expanded, but its effectiveness depends on the level to which water must ultimately drain. Rising seas reduce that difference. Land subsidence lowers the urban surface. More intense rainfall increases the volume arriving at the same time. Together, these pressures can turn a system that functioned under older conditions into one that repeatedly fails during events that residents once considered unusual.
Ho Chi Minh City’s drainage and canal system was built during the French colonial period, when the population was about two million. The system has since been expanded, but a study by the U.K.-funded Global Future Cities Programme found that it has struggled to keep pace with rapid growth. The problem, therefore, is not only that climate conditions are changing. It is also that the physical systems supporting a much larger metropolitan economy have not kept pace with the scale and speed of urban expansion.
The city’s growth ambitions make this gap more consequential. Vietnam is seeking to overhaul its economy with the goal of becoming a high-income country by 2045. Ho Chi Minh City has also merged with neighbouring provinces to create a much larger megacity, bringing together industrial hubs, services and seaports across the south. These areas do not share the same landscapes, levels of urbanisation or infrastructure conditions.
A larger metropolitan footprint can create economic opportunities, but it also expands the area that must be governed as one connected water and infrastructure system. Flooding in one locality can affect roads, businesses, industrial activity and access to services elsewhere. The report does not establish that the merger itself caused the flooding, but it makes clear that the enlarged city has inherited sharply differing conditions while trying to plan for a common future.
Authorities have recognised that existing arrangements are no longer sufficient. In July, the city launched a $13 billion plan to address 159 flood hotspots by 2030, including upgrades to flood-control infrastructure. It also adopted a climate action plan through 2030 that includes drainage and major canal upgrades, expanded green spaces and measures to improve the city’s ability to cope with heavy rain, high tides and rising sea levels.
These plans indicate a shift from treating floods as isolated emergencies to treating them as a long-term urban systems problem. Flood-control infrastructure remains important, but the city’s own circumstances show why drainage cannot be separated from land management, groundwater use, canal protection, open space and development patterns. If the ground continues to sink or waterways lose their capacity, new drains may provide only partial relief.
Groundwater extraction is one of the pressures identified in the report. Pumping water from beneath the city can cause underground layers to compact and the land above them to sink. That process leaves low-lying neighbourhoods more exposed to floodwater. It also creates a difficult governance problem because the effects of extraction are distributed across the city, while the benefits may accrue to individual users or sectors in the short term.
The evidence presented in the report points to a widening gap between the city’s inherited infrastructure and its emerging risk profile. Nearly half the land is below one metre above sea level. The drainage system was developed for a population of about two million and has struggled to keep up with growth. Parts of the city are sinking because of groundwater extraction. At the same time, sea levels are rising and heavy rainfall is becoming a greater threat. Each figure or trend is significant on its own; together, they describe a compounding risk.
The consequences are measured at street level. A roadside eatery may remain open, but customers and workers must move through knee-deep water. A vendor may continue selling food from the same pavement after years of repeated flooding, but the operating environment becomes increasingly dependent on timing, mobility and personal tolerance. Such scenes can make a city appear resilient while concealing the costs borne by people with the least ability to relocate or absorb lost income.
The regional context also matters. The report notes that heavy rains in Thailand since mid-September affected more than 2.6 million people and killed at least 19. That comparison does not establish identical causes or conditions across countries, but it shows that the wider region is facing increasing pressure from extreme rainfall and climate-related disruption. For cities connected by trade, migration and supply chains, climate resilience is not only a municipal concern.
Ho Chi Minh City’s response will therefore be tested on two levels. The first is whether the announced investments and upgrades can reduce flooding at the 159 identified hotspots by 2030. The second is whether planning can address the underlying interaction between water, land, growth and infrastructure. A city can build more flood-control assets and still remain vulnerable if development continues to increase exposure or if sinking land reduces the performance of drainage systems.
The immediate lesson from the September flooding is that adaptation is already happening, but much of it is being carried out by residents and small businesses. Raised floors, raincoats and altered routines help people cope with water after it arrives. They do not prevent disruption, restore drainage capacity or address the causes of subsidence. The city’s climate action plan and flood-control programme now provide the institutional framework for a broader response.
What the evidence confirms is a structural urban challenge: Ho Chi Minh City is facing climate risks that are being intensified by its physical condition and development trajectory. What remains to be established is how quickly the planned measures will be implemented, whether they will cover the enlarged metropolitan area effectively and whether they can address both flooding and land subsidence. Those milestones will determine whether the city is merely learning to live with water or reducing the risks that make flooding a routine part of urban life.
