Thailand warns 11 provinces of higher Chao Phraya Dam releases
Eleven Thai provinces, including Bangkok, are on alert as planned Chao Phraya Dam releases could raise water levels in parts of Ayutthaya and Ang Thong.
The Royal Irrigation Department (RID) has issued an urgent warning to 11 provinces in the Chao Phraya basin, including Bangkok, as it prepares to increase releases through the Chao Phraya Dam to between 1,500 and 2,000 cubic metres per second.
The department’s fifth notice on the basin’s water situation calls on relevant agencies and riverside communities to monitor conditions closely.
The warning follows the Thai Meteorological Department’s third advisory on heavy to very heavy rain during September 23-27, 2026, affecting the North, lower Northeast, Central region, East and South. The rainfall could trigger flash floods and forest run-off, particularly around foothills near waterways and in low-lying areas.
Upstream flows expected to increase
RID said on Wednesday (September 23, 2026) that flows through Mueang Nakhon Sawan district were expected to peak at approximately 1,800 cubic metres per second within the following one to nine days.
An additional 300-400 cubic metres per second from tributaries would bring flows upstream of the Chao Phraya Dam to approximately 2,100-2,200 cubic metres per second.
Water is also being diverted into irrigation systems on both sides of the Chao Phraya River at a combined rate of 400-450 cubic metres per second.
The department said the anticipated flows would require it to increase downstream releases through the dam.
Water levels expected to rise in Ayutthaya and Ang Thong
The planned releases are expected to raise water levels by approximately 0.70-1.70 metres above current levels in low-lying areas outside flood embankments in two provinces.
In Phra Nakhon Si Ayutthaya, the areas identified are Sena, Phak Hai, Bang Ban, Phra Nakhon Si Ayutthaya, Bang Pa-in and Bang Sai districts.
In Ang Thong, the warning covers Wiset Chai Chan and Pa Mok districts.
Eleven provinces urged to monitor conditions
The wider warning covers Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Suphan Buri, Lop Buri, Pathum Thani, Nonthaburi, Samut Prakan and Bangkok.
RID urged relevant agencies and residents along both banks of the Chao Phraya and Noi rivers to prepare for the anticipated changes and follow the water situation closely.
