Upstream water volume is continuously increasing. The Royal Irrigation Department issues the second Chao Phraya alert, preparing to release 700-1,000 cubic meters per second downstream of Chao Phraya Dam, affecting low-lying areas outside flood barriers along the river.
On 19 September 2026, the Royal Irrigation Department's Smart Water Operation Center (SWOC) closely monitored and analyzed the Chao Phraya basin water situation, finding that upstream water volume is steadily rising and flowing into the area upstream of Chao Phraya Dam. Consequently, the department must adjust water management plans and increase releases downstream of the dam to match the incoming water volume.
As of 06:00, water flow at station C.2 in Nakhon Sawan Province measured 963 cubic meters per second. Forecast analysis for the next 1-9 days indicates this will rise, with expected flow on 27 September 2026 of approximately 1,100-1,250 cubic meters per second. Additionally, tributary inflows are estimated at 50-100 cubic meters per second, resulting in total upstream water at the dam reaching about 1,150-1,350 cubic meters per second.
Given this trend, the Royal Irrigation Department must release water downstream of Chao Phraya Dam at a rate between 700 and 1,000 cubic meters per second to control upstream water levels and accommodate floodwaters from upstream areas. The release rate will be adjusted as needed based on ongoing inflows and conditions.
Releasing water at this rate will raise water levels along the riverbanks downstream of Chao Phraya Dam by approximately 0.60 to 1.50 meters, from the dam area in Chainat Province to Phra Nakhon Si Ayutthaya Province. Low-lying areas outside flood barriers in Sena, Phak Hai, Bang Ban, Phra Nakhon Si Ayutthaya, Bang Pa-in, and Bang Sai districts of Phra Nakhon Si Ayutthaya Province may be affected by the rising water levels.
However, water levels within communities protected by flood barriers remain unaffected. If upstream inflows increase further, causing releases at Chao Phraya Dam to exceed 1,000 cubic meters per second, the Royal Irrigation Department will provide updated information and water management guidance.
The Royal Irrigation Department continues to monitor and regulate water flow through Chao Phraya Dam, managing irrigation systems on both east and west sides for maximum efficiency. This includes tracking rainfall, water station data, and model forecasts to assess trends and adjust water management plans accordingly, aiming to minimize impact on low-lying and agricultural areas.
The department has informed governors of 11 provinces in the Chao Phraya basin and relevant local agencies to prepare for the situation and take necessary actions. Public announcements are made to ensure widespread awareness. Residents, especially those living in low-lying riverbank areas outside flood barriers and downstream of Chao Phraya Dam, are urged to closely follow water updates and warnings from the Royal Irrigation Department and prepare accordingly. The department will continue monitoring and promptly inform the public of any changes.
