Monsoon season is here and even though the Bangkok Metropolitan Administration (BMA) is busy tackling the spread of Covid-19, it has spared no efforts to ensure the capital is well prepared.
Bangkok governor Pol Gen Aswin Kwanmuang said City Hall workers had already completed the annual flood-prevention routine, dredging 1,984 canals with a combined length of 2,760km, unclogging sewer and main drains totalling 6,464km, checking tools and equipment at pumping stations and drainage tunnels and closely monitoring the weather.
Pol Gen Aswin said flood drainage capacity had improved. "It is impossible to say that Bangkok will be high and dry in the flood season but City Hall has better flood controls," he told media after leading them on an inspection of the drains.
The BMA has touted its giant tunnel project as an adequate flood defence system for the rainy season, which runs from May to October. Four such tunnels are now in operation.
The Bang Sue tunnel, the latest of the four main drainage projects, is expected to prove its worth this year after being disrupted last year due to a power outage, leading to major flooding on roads in the Lat Phrao, Chatuchak, Phaya Thai, Din Daeng and Bang Sue areas.
Combined with three other tunnel projects, the upgraded drainage system is expected to handle the monsoon rains and alleviate flooding in 14 of Bangkok's 50 districts.
The other three are the Prem Prachakorn tunnel, with a diameter of 3.40 metres, which will alleviate floods in Bang Sue, Chatuchak, Laksi and Don Muang; the Bung Makkasan tunnel, which is 4.60 metres in diameter, responsible for Watthana, Pathumwan, Ratchathewi, Phaya Thai, Huay Kwang and Din Daeng districts; and the Khlong Saen Saep/Khlong Lat Phrao tunnel, better known as Rama IX tunnel, which will boost drainage capacity in Huay Kwang, Bang Kapi, Bung Kum, Watthana, Wang Thong Lang and Lat Phrao districts.
The BMA also has a few other tricks to combat flooding.
In greater Bangkok, which has more green areas, the city has 31 kaem ling water-catchment areas, while two underground "water banks" are ready for use in the areas of flood-prone Asok-Din Daeng Road and Bang Khen police station.
The water banks, which are modelled on underground water banks in Japan, are concrete wells connected with pipes and gutters that can be used to retain rainwater during heavy downpours.
The BMA also has a "pipe jacking" flood control system in three areas -- Yaowarat, Charoen Krung and Sukhumvit 103. Installed in a densely populated area, which has only narrow sewage pipes, this system helps increase the drainage capacity.
Pol Gen Aswin said that with limited drainage capacity due to small sewer pipes and the city's low-lying terrain, flooding was common in the city but preparations were being made to prevent the worst. "If the rainfall is around 60-70 millimetres, draining the water will be a piece of cake," he said. "If the rainfall is 100 millimetres, we should expect inundation but it won't last four to five hours."
Narong Ruangsri, director of the BMA's Department of Drainage and Sewerage, said garbage in the draining system was partly to blame for flooding on city streets.