By Ting Chiang

Copyright bbc

On Monday 22 September, a day before Ragasa neared the island, Hualien authorities issued warnings, evacuated about 7,000 people and set up three evacuation centres. Meanwhile, the central government repeatedly urged the county administration to accelerate the evacuations.

But the evacuation was “not mandatory” and local officials only called on the public to go to higher ground, Hualien county councillor Yang Hua-mei told the BBC.

It was shortly before 15:00 local time (07:00 GMT) on Tuesday when the barrier lake overflowed. Officials had expected it would take the floodwater two hours to reach inhabited areas downstream and only people living near the river would be affected.

But within an hour, vast quantities of water were pouring into Guangfu Township, where 12,000 people live.

“There were no special flooding warnings and no broadcast,” an administrator of a high school in Guangfu told the BBC on condition of anonymity. The school was designated an evacuation centre, so he’d originally been tasked with helping evacuees.

He said he’d just finished lunch at around 15:00 when he heard the lake had burst its banks.

“Within 10 minutes, water spread to the campus from the street. The 400-sq-mile sports ground was submerged,” he said. Chairs, tables, refrigerators and even cars were soon floating.

“If I’d still been on the street, I wouldn’t have been able to reach higher ground. There were lots of objects floating in the water. I could have been hit or even electrocuted.”

The administrator said officials might have underestimated Ragasa’s impact – the lake had not breached its banks when a weaker typhoon hit last month.

Since last week, County Mayor Hsu Chen-wei had been on a trip to South Korea to promote tourism. She returned to Hualien on Monday evening – reportedly after a call from the interior minister.