The Abukuma River flooded in the wake of Typhoon Hagibis, leaving 80 dead and 12 still missing.
A "backwater phenomenon," which is when the level of a river rises too high and blocks water from its tributaries, occurred at many locations of the river system in Fukushima and Miyagi prefectures. This caused dikes of the river and its branches to burst at 41 locations.
Almost all areas along the river were flooded because the direction of the typhoon was almost the same as that of the river stream. Weather officials said some places that flooded received up to 40% of their annual rainfall in just two days, according to the Independent.
As of Oct. 20, the death toll from the typhoon, this year's 19th, stood at 80 while 12 people remained missing, according to a tally by the Mainichi. Floods from the Abukuma River contributed to this massive damage.
The Fire and Disaster Management Agency announced that the number of housing units damaged due to Typhoon Hagibis reached 56,753 in 31 prefectures across the country, reported the Mainichi Times.
"It has been rare in recent years, when flood-control measures have been implemented, for areas extending from the upper to lower reaches of a river to be flooded" said Osamu Itagaki, head of the Flood Disaster Prevention Division of the ministry's National Institute for Land and Infrastructure Management to the Mainichi.
The water level downstream remained high because of torrential rain brought by the typhoon. This and the massive amount of water from the upper reaches resulted in levee breaches at many locations. The river's dike burst at seven locations in Fukushima Prefecture.
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