Prime Minister Prayut Chan-o-cha has expressed concern over possible flooding in the Central Plains, including Bangkok, as meteorologists predict further storms late this week.
Heavy downpours and water run-off from the North have caused the Chao Phraya barrage dam to release a massive amount of water into the capital, heightening the flood risk.
The premier's remark came as the Royal Irrigation Department (RID) announced it has increased the water release rate at the Chao Phraya barrage in Chai Nat from 2,200 cubic metres (cu/m) per second to 2,600 cu/m to make room for more rainfall and the run-off expected from the upper parts of the river.
The 2,600 figure is approaching "critical point", Gen Prayut said yesterday.
The Royal Irrigation Department has set a 2,850-cu/m release rate as the maximum allowable before which flooding is likely to occur further downstream.
The prime minister also advised people in the Central Plains to keep up with weather announcements from the Meteorology Department.
He said the government is aware of the weather systems that are set to hit Thailand and is trying its best to prevent flooding, but people also need to understand the government is coping with an unpredictable natural phenomenon.
Gen Prayut said that the government's plan is to siphon as much of the excess rainfall and run-off out into the Gulf of Thailand as fast as possible so the impact on the provinces located along the two sides of the river will hopefully be minimised.
At present, the RID is managing the increasing levels of water in the Chao Phraya by diverting it into 12 large riverside fields.
It is a traditional method officials have used to deal with massive run-off from the North in the past.
So far the fields have taken on about 70% of the capacity of water they can absorb, said Agriculture and Co-operatives Minister Chatchai Sarikulya, adding officials are confident they can keep flooding under control, despite the prospect of extra storms.
The major dams in Thailand have about 20% capacity left, the minister said, adding this will help slow the water flow into the Chao Phraya and other rivers.
However, some areas, especially those located outside the Chao Phraya embankment, will not avoid an impact from water that has already been released from the river, Gen Chatchai said.
Some areas in Chai Nat's Sapphaya district are bearing the brunt.
At least 400 houses located by the river have been flooded. Many ancient temples in Ayutthaya's Phra Nakhon Si Ayutthaya district are also reinforcing their flood walls to prevent water from inundating historical sites.
In Pathum Thani's Muang district, located to the south of Ayutthaya, some riverside communities in tambon Ban Krachaeng have begun to encounter overflow from the Chao Phraya River, which has combined with a high tide, Ban Krachaeng tambon administration organisation head Winai Netphralit said yesterday.
The RID has been told to stay alert to rainfall until Saturday after the Meteorology Department warned that torrential rains will deluge Thailand towards the end of the week, Gen Chatchai said.