Irrigation Department Prepares 11 Provinces for Water Surge
The Royal Irrigation Department is preparing to release 1,500–2,000 cubic metres of water per second through the Chao Phraya Dam to handle heavy rainfall, affecting 11 provinces with water level rises of up to 1.70 metres in low-lying areas
The Royal Irrigation Department has named 11 provinces in the Chao Phraya River basin and is preparing to increase water discharge at a rate of 1,500–2,000 cubic metres per second, which will cause water levels to rise.
On 23 September 2025, Deputy Director-General Dech Lekvichaihai of the Royal Irrigation Department issued an urgent alert—the fifth such warning for the Chao Phraya basin—to governors of 11 provinces: Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Suphan Buri, Lop Buri, Pathum Thani, Nonthaburi, Samut Prakan, and Bangkok.
The Meteorological Department has issued its third warning of heavy to very heavy rainfall across Thailand from 23–27 September 2025, affecting the northern, lower northeastern, central, eastern, and southern regions. This may trigger flash floods and landslides, particularly in foothill areas near waterways and low-lying zones.
The Irrigation Department forecasts that within 1–9 days, the water gauge at Station C.2 in Mueang District, Nakhon Sawan, will record peak flow of approximately 1,800 cubic metres per second. This will be supplemented by tributary discharge of 300–400 cubic metres per second. Above the Chao Phraya Dam, the combined flow will reach 2,100–2,200 cubic metres per second, with irrigation diversion along both sides of the river totalling 400–450 cubic metres per second.
Consequently, the Irrigation Department must release water through the Chao Phraya Dam tail at a rate of 1,500–2,000 cubic metres per second, causing water levels in low-lying areas outside the embankments to rise by approximately 0.70–1.70 metres. Affected areas include Sena, Phakahai, Bang Bal, Phra Nakhon Si Ayutthaya, Bang Pa-in, and Bang Taruay districts in Phra Nakhon Si Ayutthaya, and Wisetchai and Pa Mok districts in Ang Thong.
To prepare for these conditions, the Irrigation Department has alerted the 11 Chao Phraya basin provinces, relevant agencies, and residents along both banks of the Chao Phraya and Noi rivers to monitor the situation closely.
