The Region 12 Irrigation office on Thursday issued a warning about the continuing rise in the water level of the Chao Phraya river to governors and residents of seven provinces in the Central Plains.
The provinces are Chai Nat, Uthai Thani, Sing Buri, Ang Thong, Suphan Buri, Ayutthaya and Lop Buri.
The warning said a monsoon trough lying across the North, the Northeast and the upper Central Plains from Aug 27-30 dumped heavy rain on upper Thailand, increasing runoff flowing into the Chao Phraya dam reservoir in Chai Nat province.
At 6am on Thursday, 708 cubic-metres of water per second was flowing through the dam gates, but the rate would rise to 900 cu/m per second. This would raise water levels in the river downstream from Sapphaya district of Chai Nat to Sena and Bang Ban districts of Ayutthaya.
The regional irrigation office said it would begin discharging water at 900 cu/m per second each day. Doing so would raise the water level in the Ayutthaya section of the Chao Phraya river by 80-120 centimetres. The water volume running through the Chao Phraya dam would exceed 900 cu/m per second if there were more heavy rain.
Authorities in the seven provinces were advised to warn residents and businesses on the river banks of the danger, and urge them to closely monitor the water level.
The Meteorological Department forecast that outbreaks of continuous rain will continue all over the country into Friday, but with less rain being expected.
It said there is a 70 % chance of rain in the afternoon or evening in Bangkok and its vicinity today and Friday.