Residents down river from the Pasak Chonlasit Dam in Lop Buri will soon face heavy flooding - as early as Monday. The dam, which holds the biggest reservoir in the Central region, is full and will soon have to increase release of water. (File photo)

Seven provinces in the Central Plains are bracing for between 25-75cm of flooding as irrigation authorities prepare to discharge water from the Chao Phraya dam in Chai Nat province.

Government spokesman Sansern Kaewkamnerd issued warnings to the provinces Sunday. He said a high volume of northern run-off flowing into the dam was expected today.

He said water flowing into the dam was projected to reach 2,800 cubic metres per second today.

This would make it necessary to increase the volume of excess water to be discharged from the dam from 2,000 cu/m per second now to 2,300 cu/m per second, he said.

As a result, the flooding situation in Chai Nat, Uthai Thani, Sing Buri, Ang Thong, Suphan Buri, Lop Buri and Ayutthaya was expected to intensify, he said.

Those living by or operating businesses such as floating restaurants on the Chao Phraya River were advised to move their belongings to higher ground to avoid possible damage from rising flood levels, he added. Prime Minister Prayut Chan-o-cha said he would like to thank all farmers, especially those whose rice harvest has yet to finish, for sacrificing their paddy fields to serve as water retention areas to mitigate the impact of the floods.

They would receive compensation for damage caused by the floods, said Lt Gen Sansern, adding the Interior and the Agriculture Ministries planned to survey flood damage so compensation payments could begin.

Meanwhile, the Meteorological Department warned more torrential rain storms are expected from Wednesday until Saturday in the North, the Central Plains, the East, the lower Northeast and the western coasts of the South. Rainfall was forecast to drop slightly in the North, the upper Northeast, the Central Plains, the East and the western coast of the southern region today, the department said.

In Bang Ban, one of Ayutthaya's two worst-hit districts, a 43-year-old male villager drowned on Saturday night after falling into flood waters about 1m deep just in front of his home in Moo 1 of tambon Ban Kum. Village head Chaluay Ngamrabiap identified the flood victim as Preecha Urai.

From Sunday when the rate of excess water discharged from Chao Phraya dam into the Chao Phraya River was steady at 2,000 cu/m per second, residents of Bang Ban and Sena districts of Ayutthaya saw an average flood level of 1.5m in their riverside communities.

As the government announced authorities would discharge a higher volume of water from the dam, people in the worst-hit districts were warned to deal with even deeper flood waters, possibly of more than 2m.

Thongplew Kongjun, deputy director of the Royal Irrigation Department, said the Pasak Chonlasit dam in Lop Buri province was nearing its retention capacity.

As of Sunday morning, the dam, which holds the biggest reservoir in the Central region, was able to take at most 52.5 million cubic metres more and was likely to become full Monday unless water is released.

Mr Thongplew said the department was closely monitoring water levels in the dam and considering increasing the rate of water being drained out of the dam from 50 million cu/m per day to 60 million cu/m per day.

He said the department maintained similar water management measures at the Rama VI dam.