October 04, 2012 00:00 By JANJIRA PONGRAI
Tropical Storm Gaemi to be followed by two more heading for North; capital may be hit by run-offs
Eight key areas in Bangkok could be under as much as 30 centimetres of water for up to two weeks this month, especially when Tropical Storm Gaemi brings in torrential rain this weekend, a Bangkok seminar on flood prevention was told yesterday.
The volume of rain brought by the storm could average 800 millimetres this month alone, compared with Bangkok’s annual average of 1,500mm, said Associate Professor Sujarit Khoonthanakulwong, from Chulalongkorn University’s faculty of engineering. The faculty hosted the seminar.
In addition to Gaemi, two more storms are believed to be heading to northern Thailand via Vietnam, which could bring huge volumes of rain in the North and the upper Central region.
“The resulting torrential rain will increase the volume of water in the North and Central regions, prompting floods in Bangkok,” he said.
Because of the many flood-prevention measures put in place, Bangkok is safer from widespread inundation but is still vulnerable because the heavy downpours could result in rainfall levels exceeding 100mm per day, while Bangkok’s drainage capacity stands at 60mm.
“Widespread flooding for longer periods in Bangkok is not beyond expectation if it cannot be drained in the first hour,” Sujarit said.
In the lower North, especially the Bang Rakam plain in Phitsanulok province and low-lying Ayutthaya province in the Central region, there is a possibility for the floods to continue into November. To extend the farming season, water should not be released until early December.
Phaisal Santithammanont, another speaker from the faculty, said a new network of ground control-point stakes, used as references to measure the mean sea level to help with flood prevention, would have to be built because they are either damaged or worn out. He said this could cost as much as Bt100 million, because there are at least 1,000 stakes in Bangkok alone.
The Science and Technology Ministry’s project to reinstall stakes, initially in Bangkok, will also allow untrained members of the public to read mean sea levels themselves, and this might lead to misunderstanding, he added.
Provincial authorities and irrigation officials in Samut Prakan said yesterday that Bang Phli, Suvarnabhumi Airport and other key business areas in the province should not be flooded this year thanks to the preventive measures put in place. The areas were flooded last year because they are lower than Bangkok and Nakhon Nayok and ended up getting run-offs from both provinces.
Senior irrigation official Surach Thanoosil said he could provide 100-per-cent assurance because a large number of pumps were ready for the job and that waterways and sewers had been dredged.
“The toughest period will be this weekend when Gaemi arrives in Thailand, because Samut Prakan is only vulnerable to rainwater, not run-offs from the North,” he said.