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Expert doubts Bangkok authorities' rainfall claims

Publication Date : 28-09-2012


Flawed water-drainage management, not heavy rain, is the likely culprit in the repeated hours-long flooding of Bangkok's major roads, Hydro and Agro Infomatics Institute director Royol Jitdon hinted yesterday.

"It's not about too much rain. It's about the fact that there are no systems to push rainwater quickly into water-drainage tunnels or canals," Royol said in his capacity as a member of the Strategic Committee for Water Resources Management (SCWRM).

He also dismissed the Bangkok Metropolitan Administration's (BMA) claim that the capital could deal with no more than 60 millimetres of rainfall a day.

"The water-drainage pipes in the capital clearly should be able to deal with 60 millimetres of rainfall per day," he said. "Problems should arise only if rainfall is well over 60 millimetres per hour."

And even if the rainfall exceeded 60 millimetres per hour in some spots, Royol was still convinced that the water-drainage system spanned a wide area and with the shared capacity, the system should be able to function well enough to prevent floods.

Earlier this week, the BMA called for patience and understanding from city residents, saying temporary flooding would be unavoidable in the face of hours-long cloudbursts because the capital's water-drainage system was designed to deal with up to 60 millimetres of rainwater only. Officials were quite evasive at first about whether it was 60 millimetres per day or per hour. When pressed, the BMA confirmed it meant 60 millimetres of rainfall per day.

The BMA also claimed that the capital was experiencing a historic high amount of rainfall this month. According to the BMA Drainage and Sewerage Department, the total rainfall in September this year has already reached 721 millimetres - the highest amount in three decades.

Meteorological Department deputy director-general Somchai Baimuang, however, questioned those figures. He said his department found that as of Tuesday, the total rainfall in the current month had reached just 340.7 millimetres.

"How could the rainfall nearly double within one day?" he said.

Royol did not believe the BMA rainfall figures either, saying he would compile the information himself.

He also said that the temporary flooding in Bangkok was clearly the result of flawed drainage management, pointing out that while the inbound lanes of Asoke-Din Daeng Road were not flooded, its outbound lanes were swamped.

"The inbound lanes have not had any problem because the rainwater falling on them can flow directly to the Makkasan Pond," he said.

Meanwhile, BMA spokesman Wasan Meewong said it would take time to drain rainwater in the wake of heavy downpours. He said the average rainfall in the capital was just 1,500 millimetres per year, and repeated the claim that this month, the rainfall had already reached 721 millimetres.

Making an even greater claim for the level of downpours this month, he said: "This is the biggest rainfall in 100 years."

He reckoned there were some clogged pipes and limited pumps. "But we will take fast action on major roads," he said.

When Bangkok's major roads were covered with floodwater, traffic there was almost paralysed and hundreds of thousand commuters were affected, he said.

Wasan said the flooded portions of Vibhavadi-Rangsit Road were in a very low-lying spot and that was why repeated flooding occurred.

According to Royol, heavy rain will continue in Bangkok for just two more days.

Meanwhile, heavy downpours have turned the water flow in a canal in Phang Nga into a ferocious torrent, damaging the Bang Bang Miang Bridge.

"Hundreds of people became marooned," Phang Nga Administrative Organisation deputy chair Sermpong Saridsuk said yesterday.

Phang Nga disaster prevention and mitigation officials rushed to erect a temporary bridge but the process was expected to take days.

"I think we should complete the task [tomorrow]," the office's director, Kiat Inthornkham, said.

In Ranong, flooding yesterday hit people living along the Bang Hin Canal in Kapur district.

"We will use machinery to dredge the canal and quickly drain the floodwater out of the affected areas," Tambon Ban Na Administrative Organisation chairman Sangob Jankhieo said yesterday.


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