After heavy rainfall in the northern part of the country, the Chao Phraya Dam has adjusted its plan to increase water discharge. It has warned 11 provinces in the Chao Phraya River basin, including Bangkok, to prepare for higher water levels and to closely monitor the situation.
On 21 Sep 2026 GMT+7, reporters reported that Mr. Det Lekwichai, Deputy Director-General acting on behalf of the Director-General of the Royal Irrigation Department, issued the third water situation warning for the Chao Phraya basin. This alert was sent to governors of 11 provinces in the basin: Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Suphan Buri, Lop Buri, Pathum Thani, Nonthaburi, Samut Prakan, and Bangkok.
He stated that the heavy rainfall in the northern region has caused the Chao Phraya River's water volume to rise. To manage water appropriately in line with rainfall and runoff conditions and forecasts over the next 1–9 days, it is expected that on 29 Sep 2026 GMT+7, water flow at station C.2 in Mueang District, Nakhon Sawan Province, will be about 1,400–1,450 cubic meters per second. Tributaries are expected to add 150–200 cubic meters per second, resulting in approximately 1,550–1,650 cubic meters per second of water above the Chao Phraya Dam. Additionally, irrigation systems on both sides of the basin will absorb 400–450 cubic meters per second.
Therefore, the Royal Irrigation Department must release water downstream of the Chao Phraya Dam at a rate between 1,000 and 1,300 cubic meters per second. This will raise water levels by about 0.50–1.50 meters in lowland 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. However, this will not impact riverside communities. If upstream water volume increases beyond 1,300 cubic meters per second passing the dam, further notice will be provided.
Currently, at station C.2 in Mueang District, Nakhon Sawan Province, water flow is 1,400 cubic meters per second. At the Chao Phraya Dam in Sapphaya District, Chai Nat Province, the upstream water level is 16.79 meters above sea level, downstream water level is 11.07 meters, with water level 5.27 meters below the riverbank. The dam is discharging water at 990 cubic meters per second.
To prepare for the water situation, the Royal Irrigation Department warns the 11 provinces in the Chao Phraya basin, related agencies, and residents living along both banks of the Chao Phraya and Noi Rivers to closely monitor water conditions.