HANOI: Flooding and landslides in the northern region of Vietnam have left six people dead, two missing, and 10 injured, with total economic losses estimated at nearly 443 billion dong (US$17 million), as damage continues to mount in Lai Chau and Son La provinces.
Lai Chau, a mountainous province characterised by steep terrain and a dense network of rivers and streams, has been the hardest-hit locality during the recent flooding in northern Vietnam’s mountainous region.
Flash floods and landslides directly affected 899 households, comprising 4,263 residents, in the villages of Chit, Khi, Nam Sang, Noong Thang, and Nam Ngua.
The province recorded six fatalities. Ten individuals were injured, and two people remain missing.
The disaster destroyed 28 houses, damaged a further 224 homes and affected more than 408ha of rice and other crops. Livestock production and infrastructure also sustained extensive damage.
As at noon on July 20, total losses in Lai Chau were estimated at more than 270 billion dong, a sharp increase from earlier assessments. Muong Than commune alone accounted for around 120 billion dong in damage.
In neighbouring Son La province, estimated losses also rose significantly to around 125 billion dong.
Lao Cai province also suffered extensive damage after prolonged heavy rainfall triggered flash floods, landslides and inundation. Total losses were estimated at more than 45 billion dong.
Meanwhile, Dien Bien province reported damage amounting to about 2.3 billion dong.
According to weather experts, exceptionally heavy rainfall exceeding the resilience of infrastructure in Vietnam’s northern mountainous region, combined with a sudden surge of floodwaters from upstream areas, has saturated hillsides and triggered widespread landslides, flash floods and debris flows in provinces including Lai Chau, Lao Cai, and Son La.
Nguyen Van Huong, head of the Weather Forecasting Department at the National Centre for Hydro-Meteorological Forecasting, said the most significant factor behind the disasters was the prolonged period of persistent rainfall across the north-western region over recent weeks.
The rainfall was caused by the influence of a low-pressure circulation centred over northern Vietnam at altitudes between 1,500m and 5,000m.
The system produced exceptionally heavy rain, overwhelming the capacity of infrastructure in the mountainous region.
At the same time, floodwaters from upstream areas rose sharply. Combined with rainfall that had persisted for many consecutive days, the continuous downpour left mountain slopes completely saturated, leading to landslides, flash floods and the flow of debris.
According to Huong, monitoring data shows that the north-western provinces of Lai Chau, Dien Bien and Son La have experienced almost continuous rainfall since the beginning of June.
Of the past 48 days, only five recorded no rainfall, meaning precipitation occurred on the remaining 43 days.
In Lai Chau, showers and thunderstorms have been recorded almost daily since July 4, with rainfall generally ranging from 20mm to 40mm a day.
The prolonged rain has prevented the soil from drying, leaving it continuously saturated.
“When the ground is already saturated, even a moderate or heavy rainfall event can destabilise slopes and trigger flash floods and landslides,” Huong said.
“This explains why repeated landslides have recently occurred in Son La, Lao Cai and now Lai Chau,” he said.
Referring to the deadly landslide that struck Muong Than commune on July 17, Huong said three main factors contributed to the disaster.
The first was prolonged rainfall.
At the Phuc Than monitoring station, accumulated rainfall from the beginning of July to July 17 reached nearly 800mm, saturating the soil and rock on mountain slopes and weakening their structural stability.
The second factor was the area’s topography and geology.
Muong Than has numerous steep natural and man-made slopes interspersed with small streams, while the underlying rock has undergone significant weathering. These characteristics make the area particularly vulnerable to flash floods and landslides during prolonged heavy rainfall.
The third factor was an episode of extremely heavy rain between the night of July 16 and July 17.
More than 262mm of rain fell within just over 24 hours, acting as the trigger that caused already unstable masses of soil and rock to collapse on a large scale.
In official warnings issued by the meteorological authority, Lai Chau has consistently remained under the highest-level alert for flash floods and landslides.
Regarding the weather outlook, the National Centre for Hydro-Meteorological Forecasting said scattered showers and thunderstorms are expected across northern Vietnam from the night of July 20 until around July 23, with some areas likely to experience heavy rain.
Rainfall is forecast to occur mainly in the late afternoon, evening and early morning. From July 24 onwards, only isolated showers and thunderstorms are expected.
However, the risk of flash floods and landslides will remain high across northern Vietnam, particularly in the mountainous provinces of Lai Chau, Son La, Lao Cai, Dien Bien, Tuyen Quang, and Cao Bang. - Vietnam News/ANN
