Bangkok kept on edge

national October 12, 2011 00:00

By Chularat Saengpassa
Thasong A

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Bangkok should have escaped the threat of being flooded, as water travelling southwards has passed its peak while preventive measures are in place and dykes around the city and along the Chao Phraya River are intact, a senior Bangkok Metropolitan Administ

“We are quite sure that Bangkok can be saved from flooding, after monitoring tide reports last week with the Department of Royal Irrigation [RID], and finding out that the influx of water travelling through many Central provinces has passed its peak, and the water volume in the Chao Phraya is 4,000 cubic metres per second, far under a critical level,” said Narong Jirasappakunakorn, director for the drainage information system division of the BMA’s Department of Drainage and Sewerage.

 “I can assure you of that. It’s not worrying. I guarantee it,” he added.
On Bangkok’s west, Sala Thammasop Road will act as a barrier if dykes beyond it collapse, or are destroyed by disgruntled flood victims, while many canals can accommodate water from the Tha Chin River. “This is one example of a Plan B we have,” he added. Meanwhile a primary mechanism, dubbed Plan A, such as continuing drainage and existing concrete or reinforced sandbag dykes, is intact.
In case Plan B is compromised, water can still be conveyed southwards to a royally initiated catchment area in Samut Sakhon’s Mahachai area connecting southern Bangkok. 
From the north, water travelling along the Chao Phraya River flows down Rangsit Canal in Pathum Thani, and in case of overflow, runs into nearby Prem Prachakorn canal, to be blocked by a major road that doubles as a barrier. 
Water entering Bangkok from the east from Pa Sak Dam in Lop Buri flows down Hok Wa Canal, and if it overflows or watergates are destroyed, it will travel southwards along Romklao and King Kaew roads, which also double as barriers, preventing flooding of eastern Bangkok and Suvarnabhumi Airport. The highest Chao Phraya water level was 2.27 metres above sea level at the record volume of 5,500 cubic metres per second, back in 1995, when no walls had been built. The minimum height of the dykes along the Chao Phraya is 2.5 metres, while the maximum is 3 metres in areas facing higher risk. 
“There will be no flash flooding in large waves of 60 centimetres high, because the water has passed its peak, as we have checked tide reports with the RID. The water volume at Pa Sak Dam has been stable for a week at about 1,050 units per second.” 
There is one risk factor, however, that could lead to flash flooding and high water levels – watergates or clay and sandbag barriers being destroyed by disgruntled residents, he said. But those facilities and important locations are being monitored and guarded. “In case of extreme circumstances, we must let the water flood some areas while preserving those that are more important.”
Prime Minister Yingluck Shina-watra said she had instructed military and civilian agencies to strengthen several dykes in eastern Bangkok and dredge five major canals: Phra Ong Jao Chaiyanuchit, Jorrakhe Yai, Bang Chalong, Lat Krabang and Nong Ngoo Hao. These will help drain water from heavily flooded Ayutthaya and Nakhon Sawan more easily, while preventing water from combining with tides and flooding areas it passes, she said. 
Work on this must be completed before October 15 Saturday, when peak seawater tides are expected.
The government’s Flood Relief Operations Centre said a dyke was being built at the order of Yingluck, near Rangsit Canal 8, which links the Chulalongkorn 1 canals. 
Later she flew to oversee bagging of 1.7 million sandbags for distribution to Bangkok residents, and then to observe an operation at Rangsit and Sam Wa canals in Samut Prakan, to make sure it was completed before Saturday.

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