Real-time flood alerts could keep Ho Chi Minh City moving

When there is traffic chaos caused by heavy rains, discussions usually turn to infrastructure: about how many more drainage pipes, retention ponds and pumping stations, and wider roads the city needs.

These are fundamental problems that must be addressed.

But there is also a more immediate question: When an area starts flooding and traffic begins to seize up, how can someone a few kilometers away know what is happening, so that they can decide whether to leave immediately or wait until the water and congestion ease?

Imagine there is a downpour one afternoon, and someone working in an office on Ung Van Khiem Street in Binh Thanh receives this message: "Traffic ahead is heavily congested and there is a risk of flooding. Vehicles heading toward Saigon Bridge are moving very slowly. If your trip is not urgent, consider delaying it and checking conditions again in 45 minutes."

Someone elsewhere in an unaffected area might receive a different message: "Traffic on the westbound route is still moving. Travel is possible."

The point is to give people enough information so that millions of individual decisions do not all happen at the same time.

A motorbike driver loses control on a flooded street under heavy rain in Ho Chi Minh City on Sept. 30, 2026. Photo by VnExpress/Quynh Tran

Singapore has already built an important part of such a system. Its national water agency, PUB, operates a real-time flood monitoring network with more than 1,000 water-level sensors, over 500 CCTV cameras, rain gauges, and weather radar.

The data is sent to an operations center, where flood conditions are monitored and rapid-response teams can be deployed. PUB also provides heavy-rain and water-level alerts through SMS and the MyTransport.SG app.

People in Singapore can sign up to receive text alerts when heavy rain is expected. They can also monitor water levels at up to three canals or drains near their homes or along routes they often use. The system sends updates as water levels reach 50%, 75%, 90% and then 100%.

That kind of highly localized information means people receive more than a general warning. They know what is happening in the specific places that matter to them and can adjust their travel plans accordingly.

South Korea is another example.

In July 2026, the Korea Meteorological Administration sent its new "extreme rainfall emergency text message" for the first time to Jisan 1-dong in Suseong District, Daegu, after rainfall of about 100 millimeters per hour.

Like existing heavy-rain warnings, the alert was sent based on phones’ current location. The aim was to make sure people already in a dangerous area quickly understood the situation and could take steps to stay safe.

This shows us an important point about both technology and public administration. That is disaster warnings do not have to be identical for everyone. Once the system knows where the recipient is, the information can become much more specific.

This is managing the timing of movement rather than simply managing traffic.

This distinction deserves attention. In a densely populated city like Ho Chi Minh City, I believe information of this kind can be as valuable as an extra traffic lane or a new retention pond.

The data could come from weather radars, water-level sensors, traffic cameras, vehicle-speed data, flood points, and road closures.

Instead of simply covering a city map in red, the system could analyze individual areas and give people information they can easily act on.

People in safe areas could be advised to leave before traffic volumes surge, and those still at work could be told that conditions would be reassessed after a certain period.

Location-based alerts are not far-fetched given Vietnam's current digital infrastructure.

Platforms with broad reach such as Zalo, VNeID, and telecom SMS systems could incorporate real-time flood and traffic data to identify which areas users are in.

Instead of broad, generic announcements, a warning sent at the right time and to the right location could reach people just as they are about to travel into a flooded area.

They would then have enough information to change their route or delay the trip.

Office buildings, schools, shopping malls, and public facilities should also be treated as part of the emergency-response system.

During heavy rain, keeping some people where they are for another 45 minutes or an hour, when conditions allow, may be better than having everyone step onto the streets at the exact moment when traffic and floodwaters are at their worst.

A building in such circumstances is more than a workplace. It can serve as a temporary "safety buffer" for the movement of people across the city.

An information system, of course, cannot replace drainage infrastructure. But it can do something that concrete, sewers, and roads cannot: determine the movement of people in real time.

After major downpours, one image is especially striking: Hundreds of thousands of people all trying to do the same thing at once, and that is go home.

And when everyone heads home at the same time, the city grinds to a halt.