Crisis Management: Thailand Steps Up Chao Phraya Discharge as Storm Runoff Hits
Royal Irrigation Department increases water release from Chao Phraya Dam to cope with massive runoff from Tropical Storm Kalmaegi coinciding with high tidal surge
- Thailand's Royal Irrigation Department is increasing water discharge from the Chao Phraya Dam to manage massive runoff caused by Tropical Storm Kalmaegi.
- The increased runoff from northern rivers is coinciding with a high tidal surge in the Gulf of Thailand, which is slowing the river's drainage into the sea.
- The dam's discharge rate is being raised to 2,800 cubic metres per second, while water is also being diverted into irrigation canals to mitigate flooding.
- Authorities have warned residents in low-lying areas downstream of the dam to prepare for the potential impacts of the increased water release.
The Royal Irrigation Department increases water release from Chao Phraya Dam to cope with massive runoff from Tropical Storm Kalmaegi coinciding with high tidal surge.
The Royal Irrigation Department (RID) has activated an emergency plan to manage soaring water levels in the Chao Phraya River, increasing the discharge rate from the main dam as runoff from Tropical Storm Kalmaegi pushes water levels to critical highs.
The storm’s influence has caused water volumes in major northern tributaries—the Ping and Nan Rivers—to rise sharply and flow towards the central plains.
The RID’s Smart Water Operation Centre (SWOC) reported today (November 9, 2025) that the water volume flowing into the Chao Phraya at Nakhon Sawan has reached 2,948 cubic metres per second (cms).
This influx has raised the water level above the Chao Phraya Dam in Chainat to +17.71 metres above Mean Sea Level (MSL), with continued increases expected.
Discharge Rate Raised to Avert Flooding
To mitigate the impact of the massive upstream runoff, the RID has implemented a two-pronged strategy:
Water Diversion: Utilising the full capacity of irrigation canals on both sides of the Chao Phraya Dam to divert water away from the main river.
Increased Discharge: The department began gradually increasing the water discharge rate through the Chao Phraya Dam from 2,750 cms to 2,800 cms starting at 10:00 AM today, aiming to maintain the higher rate from 3:00 PM onwards.
Tidal Surge Hampers Flow
The situation remains critical because the increased upstream runoff coincides with a period of high tidal surge in the Gulf of Thailand, forecast between November 6 and 12, 2025.
This high tide limits the rate at which water can be drained into the sea, effectively bottlenecking the system.
The RID confirmed it is actively accelerating water drainage through pumping stations along coastal canals into the Gulf of Thailand, following directives from Capt Thamanat Prompow, Deputy Prime Minister and Minister of Agriculture and Cooperatives, to reduce water volume as quickly as possible.
Authorities issued a stern warning that residents living along riverbanks and in low-lying areas downstream of the Chao Phraya Dam must closely monitor official announcements and prepare for the potential effects of the increased discharge volume.
