South-central Vietnam reels from worst flooding in half a century

The Ministry of Agriculture and Environment’s Vietnam Meteorological and Hydrological Administration released a report on the recent rains and floods on Sunday.

It says that between 7 p.m. on Nov. 15 and 7 p.m. on Nov. 21, the total rainfall received by eastern Dak Lak Province ranged between 500 mm and 1,200 mm, though some places recorded much higher precipitation.

Some 1,861 mm of rain fell at Song Hinh, 1,575 mm at Hoa My Tay and 1,363 mm at Son Long.

Gia Lai Province recorded widespread rainfall of 300–600 mm, but the highest was 1,000 mm at Canh Lien.

Khanh Hoa Province also saw exceptionally heavy rainfall of 500–700 mm, rising to 1,071 mm in Dai Lanh.

A residential area in Hoa Thinh Commune in Dak Lak Province is submerged in floodwaters on the morning of Nov. 22, 2024. Photo by Nghinh Phong

Son Hoa station in Dak Lak and Quy Nhon station in Gia Lai reported unprecedented rainfall of 601 mm and 380 mm during that period. Citing World Meteorological Organization classifications, the agency said these were "exceptionally rare events, with rainfall totals that are almost impossible to forecast accurately."

Between Nov. 15 and 21 a number of rivers in the south-central region surpassed their historic flood crests, with the Ky Lo in Dak Lak, the Ba River and the Dinh Ninh Hoa in Khanh Hoa going past their record 2009, 1993 and 1986 levels.

Record flooding simultaneously across five river basins is "extremely rare, almost unprecedented in more than 50 years of monitoring," according to the administration report.

The administration said record flooding in three river basins at a time is "extremely rare and falls outside normal design parameters."

Even accurate forecasts would not have helped cope with such unprecedented disasters, it said.

Data from the last 30 years shows that major flooding in the south-central region typically occurs before Nov. 15. This year’s event came noticeably later, "indicating shifting flood patterns and increasingly extreme, unpredictable weather."

Besides, with rainfall between late October and mid-November already being 120–200% higher than normal in the region, the soil was completely saturated, and another 300–500 mm subsequently was enough to trigger severe flooding, it said.

A combination of extreme weather patterns

Meteorologists say the heavy rainfall resulted from a combination of a number of extreme weather systems.

Strong disturbances in the easterly winds combined with a powerful cold front at high altitudes (1,500–5,000 m), creating a deep layer of moisture convergence.

Moisture from the East Sea, known internationally as the South China Sea, steadily moved inland across the central region and the Central Highlands, and the Truong Son mountain range acted as a barrier, enhancing convection and sustaining prolonged rainfall.

Rainfall of 800–1,700 mm in many areas far exceeded their natural drainage capacity.

The region's topographical and hydrological features also heighten flood risks.

Short, steep river basins cause rainwater to flow rapidly downstream, triggering flash floods and causing water levels to rise within hours.

Inland water levels rose while large waves of three to five meters slowed drainage into the East Sea.

Climate change is also intensifying extreme rainfall and reducing predictability.

Severe floods have become more and more frequent in the last 10–15 years, with many stations recording unprecedented rainfall of 1,000–1,700 mm per event.

Forecasting, warning systems need change

Professor Dr. Tran Thuc, the administration's president, said in the context of climate change and increasingly extreme weather, forecasting and warning systems need a makeover.

This time forecasters had predicted the general rainfall areas correctly though not precise totals at certain localities, with some stations exceeding forecast amounts, he said.

But this is a common limitation in tropical monsoon regions with complex terrain, where localized heavy rains are extremely difficult to predict, he said.

Landslide warnings also remain broad and general, typically published as "high risk in certain communes or wards" without pinpointing specific slopes or road sections, he said.

Automatic monitoring stations in upstream and rural mountainous areas (where flash floods originate) in the south-central region remain few and far between, and generate insufficient real-time data for early warnings, he said.

A baby, soaked in floodwaters, burst into tears while being carried by his mother out of the flooded zone in Nha Trang in Khanh Hoa Province, Nov. 19, 2025. Photo by VnExpress/Bui Toan

Thuc called for making changed to address the situation.

He pointed to the need for increasing the density of monitoring networks by installing automatic rain gauges and specialized hydrological stations in upstream zones and rural areas where mobile signals are weak and enhance weather radar systems to provide detailed scans of clouds and rainfall, facilitating ultra-short-range warnings.

Weather forecast agencies should develop machine-learning AI models based on local flood history to provide real-time urban flooding and landslide warnings and create large-scale disaster risk maps for areas with high populations, he said.

He called for a shift toward "impact-based forecasts," meaning that instead of simply announcing "200 mm of rain," forecasts should specify consequences such as, for example, which roads would be submerged and by how much, landslide risks on particular passes or which dikes may be overtopped, which would help local authorities and residents better understand danger levels.

He also emphasized the need to tighten reservoir operation protocols in the short and steep south-central river basins.

Flood releases must be optimized using rainfall forecasts to avoid "flood-on-flood" situations downstream, and warnings must be delivered directly to residents on multiple platforms, even during power outages or local network failures, he said.

At least 91 people have been killed by floods and landslides that started a week ago, with Dak Lak Province reporting the highest number of fatalities at 63, the ministry’s department of dyke management and flood and storm control announced Sunday.

Rains have eased and floodwaters have started receding across the region from Saturday, but the risks remain high, it said.

Authorities estimate losses at nearly VND13 trillion (US$496 million).

 

 

South-central Vietnam reels from worst flooding in half a century

Flooding in south-central Vietnam