The Royal Irrigation Department (RID) warned 11 provinces in the Central region about the increasing water discharge rate from the Chao Phraya Dam, a move that aims to mitigate the effects of super typhoon Yagi.
Det Lekwichai, RID acting director, said on Saturday the warning was issued for Bangkok, Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Ayutthaya, Suphan Buri, Lop Buri, Pathum Thani, Nonthaburi and Samut Prakan.
He said the RID will increase the discharge rate for the Chao Phraya Dam in Chai Nat from 300 cubic metres per second to 1,500–1,700m³/s due to a heavier downpour expected in the next seven days.
As a result, the water level along the river will rise from the current level of about 20–50cm in low-lying areas, especially the community areas near Phong Phaeng Canal in Ang Thong and two districts in Ayutthaya, including Phak Hai and Sena.
According to the RID, at least 1,600m³/s of water will pass the water station in Nakhon Sawan's Muang distrit on Thursday.
The RID is allowed to discharge up to 2,000m³/s but it will only gradually do so, Mr Det said, adding the department will also warn people living along the Chao Phraya River ahead of time.
He said the RID is preparing for more rain, an impact of the super typhoon Yagi.
The Thai Meteorological Department said Yagi, now considered Asia's most powerful storm this year, hit Vietnam on Saturday. The super typhoon will weaken into a tropical storm and a depression, respectively.
Although Thailand will not be directly hit by Yagi, it will cause heavy rain in the upper Northeastern and North regions of Thailand with strong gusts of wind in some areas until Tuesday. Some mountainous areas, especially the hillsides in Nan, Chiang Rai and Phayao, may face flash floods.