Bangkok Warns of Chao Phraya River Rise of 0.60 to 1.50 Metres on 27 September
Bangkok City Hall is preparing for the Chao Phraya River to rise by 0.60 to 1.50 metres around 27 September 2026 and has opened a 24-hour flood hotline.
The Bangkok Metropolitan Administration's Department of Drainage and Sewerage has warned residents living along both banks of the Chao Phraya River to prepare for rising water levels around 27 September 2026, after the Royal Irrigation Department was required to increase the release of water downstream of the Chao Phraya Dam due to a rise in the volume of upstream water flowing through Nakhon Sawan province. Mr Jetsada Chanthraprapha, Director of the Department of Drainage and Sewerage, said the department has already coordinated with 10 central provinces and relevant agencies to prepare prevention plans and issue advance warnings.
At the C.2 water gauge station in Mueang Nakhon Sawan district, the water flow on 27 September is expected to be approximately 1,100 to 1,250 cubic metres per second. This will require the release of water downstream of the Chao Phraya Dam at a rate of 700 to 1,000 cubic metres per second, raising the current water level in the Chao Phraya River by a further 0.60 to 1.50 metres. This will particularly affect low-lying areas outside the flood barriers in several districts of Phra Nakhon Si Ayutthaya province, while communities within Bangkok's flood barrier system will not be affected.
Risk Areas and Flood Defence Preparations
Bangkok has flood defences along the Chao Phraya River, Khlong Bangkok Noi and Khlong Maha Sawat totalling 88 kilometres in length. Of this, 80 kilometres are Bangkok Metropolitan Administration defences, 3.65 kilometres are defences maintained by private parties and other agencies, and approximately 4.35 kilometres do not yet have complete defences. Sandbags have already been added to these incomplete sections to guard against seawater surges, reinforcing them to a level of 2.40 to 2.70 metres above mean sea level.
Outside these flood defences there are approximately 11 residential communities, totalling 320 households, spread across 6 districts: Dusit, Phra Nakhon, Bang Kho Laem, Yannawa, Bangkok Noi and Khlong San. The Department of Drainage and Sewerage has stationed officials to monitor these points, installed pumps in some areas, and planned the operation of drainage gates in line with the rise and fall of seawater from the Gulf of Thailand, in order to reduce the impact on riverside communities.
Channels for Monitoring the Situation and Reporting Emergencies
The Bangkok Metropolitan Administration has opened several channels for the public to monitor the water situation, including Chao Phraya River tide times, water level forecasts from the Royal Thai Navy Hydrographic Department, and the Bangkok Metropolitan Administration and Bangkok Flood Prevention Centre Facebook pages. Anyone experiencing flood-related difficulties can report them via the hotline on 0 2248 5115 or through the Traffy Fondue application, both available 24 hours a day.
| Details | Information |
|---|---|
| Date of expected water rise | 27 September 2026 |
| Water release downstream of Chao Phraya Dam | 700 to 1,000 cubic metres per second |
| Expected water level rise | Approximately 0.60 to 1.50 metres |
| Main affected area | Low-lying areas outside flood barriers, Phra Nakhon Si Ayutthaya province |
| Length of Bangkok's flood defences | 88 kilometres (BMA 80 km, private/other agencies 3.65 km, incomplete 4.35 km) |
| At-risk communities outside flood defences | 11 communities, 320 households, across 6 districts |
| Emergency hotline | 0 2248 5115 or Traffy Fondue application, 24 hours a day |
This news is relevant to hotel and restaurant operators located along the Chao Phraya River, organisers of outdoor events near the riverside, and tourists and members of the public planning to travel through riverside areas in late September, who should monitor the situation closely to plan ahead.