Northern Vietnam needs to shift from fighting floods to living with them: scientist

In an exclusive interview with VnExpress, Dr. Dung, director of the Hydrology and Oceanography Research Center at the Vietnam Institute of Meteorology, Hydrology and Climate Change, speaks about the unusual flooding caused by Typhoon Matmo, and proposes solutions.

Matmo weakened into a tropical depression as it reached Vietnam on Oct. 6, but nevertheless caused heavy downpours across the north, causing widespread flooding.

Doctor Luong Huu Dung in a photo he provides.

How do you assess the flooding caused by Typhoon Matmo?

The rains from Typhoon Matmo from Oct. 6 to 8 were quite unusual. Typically, in northern Vietnam, major floods occur in August or early September, but this year's came as late as October.

During this period meteorological agencies recorded 20 rainfall episodes, mainly in Tuyen Quang, Thai Nguyen, Lang Son, and Bac Ninh [provinces].

In the former Bac Kan Province, now merged with Thai Nguyen, rainfall on Oct. 7 reached 201 mm, breaking a 61-year record. The same day Thai Nguyen received 491 mm of rain, more than twice the 201 mm recorded in 1978 and higher than the total rainfall in all of October 1964. The former province of Bac Giang, now merged with Bac Ninh, received 365 mm, triple the 2016 record of 120 mm.

Widespread heavy rains caused rivers to rise rapidly, breaking many previous records. Flood levels in the Cau River in Thai Nguyen of 29.9 m were 1.09 m above the historical peak of last year. The level in the Thuong River in Lang Son went past the 1986 record by 1.77 m to 24.31 m and in the Bang River in Cao Bang also exceeded the historic record by 0.58 m.

For two consecutive years (2024 and 2025), northern Vietnam has experienced massive flooding, often reaching or exceeding historic levels. This is extremely rare and highlights the increasing extremity of weather patterns that need serious attention.

Why did flooding mainly affect the four provinces of Thai Nguyen, Lang Son, Cao Bang and Bac Ninh?

The historic October 2025 flood resulted from a rare combination of extreme weather conditions. After Typhoon Matmo weakened into a low-pressure system over land, its circulation remained strong and interacted with a wind convergence zone at altitudes between 1,500 and 5,000 m.

An aerial view of a flooded commune in Lang Son Province, northern Vietnam, Oct. 9, 2025. Photo by VnExpress/Ngoc Thanh

This created a particularly dangerous setup: typhoon circulation brought enormous moisture from the sea, while the convergence zone acted like a "machine" lifting this moisture upward, causing intense condensation and extreme rainfall.

Unfortunately, the heaviest rains centered over Thai Nguyen, Lang Son, Cao Bang, and Bac Ninh, areas with a mixture of midland and lowland terrain, dense river systems but limited drainage capacity. This overlap caused severe flooding.

On Oct. 14, six days after the rains had ceased, water levels in the Cau and Thuong rivers in Bac Ninh remained at warning levels, and many riverside communes in Bac Ninh and Hanoi were still flooded. Why is the flooding lasting so long?

Bac Ninh and Hanoi lie downstream, receiving water from Thai Nguyen, Bac Giang and Lang Son through the Cau and Thuong rivers. Though rainfall has stopped, massive volumes of upstream water continues flowing downstream, keeping river levels high.

Flooding in Xuan Cam Commune of Bac Ninh Province, October 2025. Photo by Van Tinh

The land in these areas was already saturated from prolonged rains, overwhelming the drainage systems. Water flowing into rivers, lowlands and residential areas could not drain fast enough.

In addition, the region's flat terrain, meandering rivers and encroachments on floodplains prevent water flow. With the gentle gradient, drainage is naturally slow. All these factors combined mean water recedes slowly even after the rain stops.

What should be done as floods occur more frequently and with increasing intensity, affecting tens of millions of people in northern Vietnam?

Flood control and water management need a shift in mindset. Rainfall and flood magnitudes in recent years have surpassed human and infrastructure capacity.

Instead of fighting floods, we must proactively prevent, adapt to and live with floods, especially in areas without large reservoirs or strong dike systems.

Previously, the concept of "living with floods" was mostly applied to the Mekong Delta or central Vietnam, where people proactively adapted. But given what has happened in the north in recent years, it could use that mindset.

Why should we learn to live with floods instead of investing in higher, stronger dikes?

The dike systems in northern Vietnam were built decades or even centuries ago and designed to withstand floods occurring once every 10 to 100 years.

However, today's extreme floods exceed those capacities. While reinforcing and upgrading dikes is essential, we cannot endlessly build higher dikes or completely redesign urban layouts. Therefore, living proactively with floods under the new paradigm is the more sustainable path.

 

 

Northern Vietnam needs to shift from fighting floods to living with them: scientist

Ngập lụt Bắc Ninh nhìn từ trực thăng

Regarding what solutions for responding to extreme events and adapting over the long term, I'd like to propose two groups of solutions:

The first involves regularly repairing and reinforcing the dike system, dredging rivers and canals, expanding urban drainage systems, and preventing any encroachment on riverbeds and flood corridors. Besides, it is necessary to plan for more areas that can contain, store or divert floodwater according to the specific characteristics of each river basin, thereby reducing pressure on the main system.

The second includes non-structural measures: Plant more forests in upstream areas, implement reasonable land use planning, preserve natural flood drainage areas, and update or create design standards to account for recent extreme rainfall and to match the capacity of current dikes, reservoirs, and pumping stations.

At the same time Vietnam must improve forecasting and warning systems, and prepare emergency response plans for evacuation, rescue and relief.

Applying modern technology and mastering flood forecasting and management systems are crucial. In the context of climate change, only through the combination of science, technology, and coordinated management can we minimize losses to people and the economy.