Heaviest rainstorm in 400 years: bureau
An overnight deluge left Aberdeen flooded yesterday. Fortunately, statistics show that level of storm happens just once every 430 years.
The torrential rain that led to the first black rainstorm warning of the year was concentrated between 1am to 4am to the west of Hong Kong Island.
The Drainage Services Department reported 16 cases of flooding - 14 on Hong Kong Island and three in Kowloon. It recorded 166.5mm of rainfall between 1.20am and 2.20am in Aberdeen. The second worst-hit area was the Peak, where 146mm was recorded between 1.30am and 2.30am.
The department's technical secretary, Robin Lee Kui-biu, said 166.5mm of rain within an hour was rare in the city.
'This is an extremely high rainfall and the chance of its occurrence is very low. It could only happen once in 430 years,' he said. The department uses rainfall records for the past 100 years to project back more than four centuries.
Mr Lee said the department's drainage system had worked effectively to channel rain into the sea. The black rainstorm signal is hoisted when more than 70mm of rainfall is recorded in an hour.
Mr Lee said it was lucky the torrential rain occurred in a short period before dawn and did not affect many residents. He said teams of officers had been sent to clear blocked drains after reports of flooding.
According to the Hong Kong Observatory, the storm was caused by an active trough of low pressure in coastal areas of Guangdong.
'The rain on Monday was the heaviest in some areas such as Aberdeen, Pokfulam and Happy Valley since we have had such records in 1984,' observatory senior scientific officer Leung Wing-mo said.
Sunny periods are expected today and tomorrow but more rain is due on Thursday, as another low-pressure trough brings showers to southern China. Mr Leung added that heavy rain and thunderstorms would hit the city on Friday.
Yesterday's rain trapped three men and two women at a water catchment at Village Terrace in Happy Valley. They were rescued by firefighters. The Peak tram was suspended for more than three hours from 6am yesterday as flooding disrupted its electricity.
