Ayutthaya river levels may rise 1.5m under dam outflow plan
The Royal Irrigation Department expects inflow above Chao Phraya Dam to reach 1,100-1,200 cubic metres per second and plans diversions on both sides.
Water levels in low-lying areas of six districts in Ayutthaya could rise by 0.60-1.50 metres if the Royal Irrigation Department adjusts discharge through Chao Phraya Dam to between 700 and 1,000 cubic metres per second.
The department is preparing to manage rising flows from the upper Chao Phraya basin by diverting part of the water into irrigation networks on the eastern and western sides of the river and adjusting dam outflow according to conditions.
People living in low-lying areas along the Chao Phraya River and downstream of the dam have been advised to follow official water updates closely.
Upstream flow forecast to increase
Wittaya Kaewmee, director-general of the Royal Irrigation Department, said on Tuesday (August 25, 2026) that monitoring by the Smart Water Operation Centre showed flows at the C.2 gauging station in Mueang district, Nakhon Sawan, were likely to increase during the coming nine days. His official English name and current position are listed by the department as Wittaya Kaewmee, director-general.
The flow at C.2 is forecast to reach approximately 1,000-1,100 cubic metres per second on August 28.
A further 60-100 cubic metres per second is expected from tributaries, taking the total flow immediately upstream of Chao Phraya Dam to about 1,100-1,200 cubic metres per second.
The department plans to take part of that volume into irrigation systems on both sides of the river. It will also consider adjusting discharge through the dam in line with the developing situation.
Six Ayutthaya districts could be affected
If outflow is adjusted to about 700-1,000 cubic metres per second, downstream water levels could rise by approximately 0.60-1.50 metres from their current levels.
The areas potentially affected are low-lying locations outside flood embankments in:
- Sena district
- Phak Hai district
- Bang Ban district
- Phra Nakhon Si Ayutthaya district
- Bang Pa-in district
- Bang Sai district
The warning applies to vulnerable low-lying areas within those districts rather than the districts in their entirety.
Further warnings to follow if flows rise
The Royal Irrigation Department said it would continue monitoring and assessing upstream flows and notify relevant agencies and residents if water volumes were likely to increase further and affect downstream areas.
Officials will also monitor rainfall and floodwater moving from the upper basin while managing the irrigation networks and dam outflow to minimise disruption to the public.
Residents in low-lying riverside communities and areas below Chao Phraya Dam were urged to monitor official announcements closely as conditions develop.
