Drainage capacity 'three times higher than last year' in west Bangkok

Yesterday’s test of the efficiency of canals in draining flood water from western Bangkok ran smoothly, according to the National Water Resources and Flood Policy Committee (NWFPC).
Meanwhile, more than 1,000 rai of paddy field in the “rice bowl” province of Ayutthaya was flooded yesterday when the water level in the Chao Phraya River rose by one metre, possibly as a result of the water drainage test.
“The results of the test were satisfactory,” said Science and Technology Minister Plodprasob Surassawadee, who chairs the NWFPC.
The NWFPC started the country’s first ever drainage test in western Bangkok at 2pm. For the next four hours water was released from Mahasawas Canal into Thawee Wattana Canal and coursed through Phasi Charoen Canal before flowing into Bang Waek and out through Phraya Ratchamontri Canal and the Tha Chin River.
The capacity of canals in western Bangkok was found to be three times higher than last year. The test goal of 7 cubic metres per second of flow was surpassed, with capacity reaching as high as 20 cubic metres per second.
As a result, the committee will be able to increase drainage in the canals from 12 to 13 cubic metres per second in the event of flooding.
“This water-drainage test was aimed at evaluating the minimum capacity of the canals to drain water,” said Plodprasob.
Places where the canals narrow and get shallow were identified as weak points for drainage. Also noted yesterday were constructions such as small bridges that hindered the flow of water.
“We will discuss the test result and seek to improve the model to solve flood problems,” Plodprasob said.
Royol Chitradon, director of the Hydro and Agro Informatics Institute (HAII) and a member of NWFPC, said there was no overflow of water into communities near the canals during the drainage test. The water level in the tested canal had risen by only 4 to 5 centimetres. “ We were able to control the situation,” he said.
“We are confident that the another drainage test this Friday will go well.”
Royol also denied reports that the flooding in Ayutthaya resulted from the test. “The Ayutthaya flood was the result of heavy rain. The areas under water are not on the test’s route,” he said.
Engineering Institute of Thailand water expert Suwat Jittaladakorn said the drainage tests were ineffective because they involved the release of too small an amount of water.
Local residents crowded the Thawee Wattana canal side to observe the drainage test. Many of them said they had no worries about their homes being flooded as they trusted the government would ensure safety in running the tests. However, they wanted the authorities to clear rubbish and sandbags blocking the drains in the area.