Sai River overflows in Mae Sai after heavy downpours trigger flash flooding

Sai River overflowed early Monday in Chiang Rai’s Mae Sai district after 118.8mm of rain, prompting evacuations and flash flooding in several villages.

Residents in several communities in Chiang Rai’s Mae Sai district began evacuating to higher ground early on Monday after hours of heavy rainfall caused the Sai River to swell and overflow.

The Tambon Mae Sai Municipality announced at 8:21am that the situation had become critical, with rainfall recorded at 118.8 millimetres.

According to the municipality, the Sai River’s water level reached 398.31 metres at the Mae Sai Friendship Bridge, leading to overflow and flash flooding.

Officials said the water level was expected to rise sharply later in the day due to continued heavy rain upstream, which would increase the river’s flow.

The municipality also urged residents to evacuate or move belongings to upper floors immediately.

Meanwhile, Warayuth Komboon, chief of Mae Sai district, said the river began overflowing at 4:20am.

He explained that while the flood levees had not yet been breached, water had seeped through leaks and sewer pipes connected to the river.

In some areas, water penetrated through decaying large sandbags previously used to reinforce the flood barriers.

At 6:00am, the river overtopped its banks near the Jotada water station in Myanmar, and by late morning, floodwaters had reached Ban Koh Sai village, Ban Mai Lung village, and Ban Pham Kwai Muan Daeng village.

(2025/07/28-00:00)