The Bangkok Metropolitan Administration (BMA) swung into action after river levels hit 1.92m on Thursday night.

Bangkok deputy governor Wallop Suwandee yesterday inspected the river at the Krung Thon Bridge and Sam Sen fire station. He said the BMA was using as many as 400,000 sandbags to build 2.2m-high flood barriers.

The barriers were placed at 14 risk areas that experienced minor flooding on Thursday night - including Maharat and Phra Chan piers and many sois of Charan Sanitwong Road.

Water levels were expected to hit 1.95m about 9.40pm yesterday, at which time Wallop and city officials would revisit the 14 risk spots.

Wallop said disaster-prevention crews in boats were advising riverbank residents to prepare to evacuate and vessels to travel slowly.

Navy Hydrographic Department deputy director Rear Admiral Nakhon Thanuwong said rising tides, the southwesterly monsoon, upstream flooding and recent heavy rain were responsible for the higher-than-usual levels.

Tides were expected to swell river levels to 1.16m on Thursday, but a combination of rain and floodwater from the north increased that by 76 centimetres.

These conditions are normally experienced in September and their early arrival prompted the department to check the river daily.

Nakhon said Chao Phya levels would remain high for as long as four more days and could rise another 10cm to 20cm.

Today's highs are predicted at 1.90m at 10.44pm and tomorrow at 1.87m at 11.41pm, he added.

Royal Irrigation Department director-general Samart Chokana-pitak insisted it was draining just 1,600 cubic metres a second via dams between Chai Nat and Bang Sai district in Ayutthaya, far less than last year.