Northern river floods reach highest levels in over five decades

Over the last three days, all 25 cities and provinces in northern Vietnam have experienced heavy rainfall following typhoon Yagi, typically ranging from 200-400 mm. The northwestern provinces of Lao Cai, Yen Bai, and Thai Nguyen were dumped with 400-600 mm, and up to 760 mm in some locations.

Nguyen Hoang Hiep, Deputy Minister of Agriculture and Rural Development, said the rainfall in provinces like Lang Son, Yen Bai, Lao Cai, and Thai Nguyen on a single day was double the typical September average of previous years.

"This is the most concerning impact of typhoon Yagi. The heavy rains have caused flooding, posing a high risk of flash floods, landslides, and threatening the dyke system," Hiep said.

The National Center for Hydro-Meteorological Forecasting (NHMF) said the heavy rains in the north were influenced not only by the aftermath of typhoon Yagi but also by a tropical convergence zone moving through the region.

The center said these weather patterns will continue to cause widespread heavy rainfall in the north until Sept. 12, adding that in the next two days, heavy rain will persist in the midlands and northern mountainous areas, with expected totals of 70-150 mm, and some locations could see more than 350 mm of rain.

On Sept. 10-11, rainfall is expected to decrease but will still range from 40-80 mm, with some areas receiving over 150 mm. By Sept. 13, rainfall will further diminish, pouring in only a few areas, it said.

The Red River Delta, which includes Hanoi, is forecast to receive 70-150 mm of rain, with some areas potentially seeing more than 300 mm from Sept. 9-11, resulting in river floods.

The flooding is most severe along the Thao River, the upper stretch of the Red River that flows through Lao Cai, Yen Bai, and Phu Tho. At 7 p.m. on Sept. 9, the water level in Lao Cai reached 87.27 meters, surpassing the historical peak from 1971 by approximately 0.27 meters.

On the Cau River, which runs through Bac Kan, Thai Nguyen, Bac Giang, Hanoi, and Bac Ninh, the water level peaked at 28.71 meters, exceeding the 1959 flood record by about 0.57 meters.

The NHMF warned of a very high risk of landslides in 17 northern provinces, including Quang Ninh, home to UNESCO heritage site Ha Long Bay.

Typhoon Yagi, the strongest storm to hit the East Sea in three decades, escalated into a super typhoon last Thursday, with winds reaching 201 kph. The storm has left 65 people dead and 40 missing across northern Vietnam, primarily from landslides, floods and falling trees.

On Monday morning, Phong Chau Bridge across the Red River in Phu Tho Province collapsed, sending 10 cars and two motorcycles into the river, according to initial reports. While three people were rescued, 13 remain unaccounted for as search efforts continue. The Phu Tho Transport Department attributed the collapse to the effects of typhoon Yagi, which brought heavy rain and flooding, rapidly increasing the river’s water level and altering the riverbed's terrain.