Sri Nakharin and Vajiralongkorn dams in Kanchanaburi province have started to overflow. (File photos)

The governors of Kanchanaburi, Ratchaburi and Samut Songkhram attended an urgent meeting Wednesday to prepare their provinces for excess water being released from the Sri Nakharin and Vajiralongkorn dams, which could cause widespread floods in the coming days.

Gen Chatchai Sarikulya, a deputy prime minister, said those present discussed ways of combatting the floods that are expected to be unleashed when the water is discharged from the dams in Kanchanaburi.

Both are taking in large amounts of water as heavy runoff from the Tanaosi mountain range along the Thai-Myanmar border continues to flow into them.

Gen Chatchai said the situation requires immediate attention as the dams are connected to the Kwae Noi and Kwae Yai rivers.

If more water is released it would quickly raise the level of both rivers, with the knock-on effects being keenly felt in downtown Kanchanaburi as well as in Ratchaburi and Samut Songkhram.

Kanchaburi city centre is located at the confluence of the Kwae Noi and Kwae Yai rivers. Ratchaburi and Samut Songkhram, meanwhile, are likely to suffer flooding from the Mae Klong River, which passes through both provinces and receives water from the other two rivers.

Gen Chatchai said a clear assessment of the water situation in the provinces must be made without delay. The governors need accurate information at their disposal so they can inform residents to ensure they are sufficiently prepared, he added.

The deputy premier said more wet weather is on the way this month in many parts of the centre of the country, including Kanchanaburi. Both the Sri Nakharin and Vajiralongkorn dams are likely to take in more water than they can store, officials said.

"We have no option but to manage the water well. If we had nothing planned, and the water inflow proves to be excessive, the impact could be severe," Gen Chatchai said.

The water released from the dams must be regulated to spare downstream communities from heavy inundation, he added. However, officials also must take into account future water usage during the dry summer months, he said.

Gen Chatchai said he will chair an inter-agency meeting on the national water management plan on Sept 14, when the Meteorological Department is expected to have a clear outlook for the rest of the rainy season.

In Prachin Buri, more than 30 homes were almost submerged in a flash flood in Prachantakham district Wednesday that left residents no time to move their belongings to higher ground.

Water was still rising in tambons Pho Ngam, Bu Fai and Nong Kaew and forced several schools to suspend classes as many children were left stranded inside their flooded homes. The flood was triggered by runoff from the Pheka mountain range, which raised the water level at the Tharn Thip waterfall. The waterfall flooded quickly, with water submerging vast tracts of farmland and many residential areas in the three tambons.