Flood waters from the north threatened to breach the capital's last line of defense and the area's 50 district offices were ordered to be ready to evacuate people in the region, the Bangkok Post reported Thursday. The capital area has a population of more than 10 million people.
The major threat was from flood waters from Nakhon Sawan (Heavenly City) in northern Thailand rushing into Bangkok. Nakhon Sawan is the meeting place of four rivers.
Many of Thailand's 77 provinces have been ravaged since July by floods that followed relentless torrential rains. More than 280 people have died and the floods have hit the country's industrial and agriculture sectors hard. Thailand is the world's largest rice exporter.
The government has appealed for hundreds of thousands of sandbags to protect the capital area. Workers have set up a 1.8 mile-long and 5-foot tall sandbag-lined flood protection wall.
Thai Prime Minister Yingluck Shinawatra and Bangkok Gov. Sukhumbhand Paribatra have warned none of the capital areas may be spared flooding or heavy rains in the forecast, the Thai News Agency reported. The Bangkok Metropolitan Administration has been busy draining water from canals in the capital.
Sukhumbhand warned as many as 27 communities in eastern Bangkok were likely to be hit the hardest, the Post reported.
"All zones in Bangkok stand an equal chance of being flooded because we can't predict the water flow," he was quoted as saying.
He did not rule out flooding of the capital's busy Don Muang International Airport.
The worst-affected areas so far have been Thailand's north, northeast and central plains, where many of the provinces were inundated and their roads under water.
Ayutthaya Province in the north, seat of the ancient capital and a World Heritage Site, is one of the worst-hit and emergency workers have been evacuating people from there. Ayutthaya is one of the country's main industrial areas, accounting for 15 percent of Thailand's manufacturing output, but about 200 plants and factories have been closed -- including that of the Japanese automaker Honda and major electronics makers.
Nationwide, 930 factories in 27 provinces have been affected by the floods, with the most damage in Ayutthaya, Lop Buri and Nakhon Sawan, the Post reported.
A deputy governor of the Bank of Thailand, the country's central bank, said the flooding would affect manufacturing output significantly during the next few months but rehabilitation will spur the economy in early 2012. The government expects the flooding to shave as much as 0.9 percentage points from economic growth this year.
Experts say the exact overall economic damage cannot be assessed as the situation has not stabilized.
CNN reported the flooding has already affected about 8 million people.
"It's really quite serious, these are the worst floods in Thailand since 1949," said an International Red Cross official in Bangkok.
He said the floods have destroyed 2.5 million acres of farmland and affected hundreds of villages and towns.
Heavy rains and floods this year also have hit Cambodia, Laos, and the Philippines.