CHIANG RAI – The Director-General of the Department of Disaster Prevention and Mitigation (DDPM) has called on the Chiang Rai governor to push Myanmar for urgent dredging of the Sai River.
The Sai River has become shallow and its width has shrunk to a quarter of its former size. Even a brief rain now causes floodwaters to rise. With this year’s wet season expected to start early, officials worry about the risk of intense downpours known as a “Rain Bomb.”
Mr. Phasakorn Boonyalak, DDPM Director-General, and Mr. Charin Thongsuk, Chiang Rai governor, recently inspected the Sai River at the Thai-Myanmar Friendship Bridge in Mae Sai district.
Rain on 29 April in Myanmar led to flooding on both the Thai and Myanmar sides. Mr. Phasakorn explained that even light rainfall now triggers flooding because sediment left by last year’s major flood has built up in the riverbed.
He said the river, once over 200 metres wide, has narrowed to less than 50 metres. No dredging has taken place for years. After the last flood, Thailand and Myanmar agreed to split the dredging work.
Myanmar is responsible for the section flowing through Tachileik and Mae Sai, while Thailand will handle the Rauk River downstream. Thailand expects to finish its part by 20 June.
However, Myanmar has not yet started any dredging work. The DDPM chief has told the Chiang Rai governor to hold urgent discussions with Tachileik officials. The rainy season starts in May, and the Meteorological Department expects heavy rain this year.
Mr. Phasakorn noted that the rain usually arrives earlier in the year. In May, showers should become frequent, with less rain expected later in the season. The actual rainfall may be similar to last year, but its timing is unpredictable.
Chiang Rai has faced “Rain Bomb” events before, with 400-500 millimetres falling in a single day. Mining on the Myanmar side may add more sediment to the river, making flooding worse. Even a little rain now causes the Sai River to overflow.
He asked officials to speed up talks with Tachileik as an immediate measure.
He added that discussions with Myanmar could involve both provincial leaders and border committees. If flooding hits, Myanmar will likely face the worst effects.
Thailand and Myanmar planned to dredge the river from 18 April to 20 June 2025. Myanmar agreed to clear the section upstream to Koh Chang, Mae Sai, while Thailand’s work runs from Koh Chang to Chiang Saen.
The Thai military’s engineering corps and border task force have already started work, building permanent and temporary embankments along three kilometres from Hua Fai to the second bridge. Myanmar is also building embankments but has not yet used machinery for river dredging.
