Rising water levels warning for Chao Phraya Basin provinces

The Royal Irrigation Department issued a warning on Monday for residents of 11 provinces in the Chao Phraya River Basin, including Bangkok - prepare for rising water levels as heavy rain in the north increases the river's flow.

RID deputy director-general Det Lekwichai issued the third warning to the governors of 11 areas - Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Ayutthaya, Suphan Buri, Lop Buri, Pathum Thani, Nonthaburi, Samut Prakan and Bangkok.

Persistent heavy rainfall upstream was increasing flows into the Chao Phraya River. The RID expected the water flow at the C.2 monitoring station in Muang district of Nakhon Sawan would reach 1,400-1,450 cubic metres per second by Sept 29.  

Water flowing into the river from tributaries was expected to add another 150-200 cu m/sec.

That would bring the volume of water upstream of the Chao Phraya Dam to about 1,550-1,650 cu m/sec. The irrigation system on both sides of the Chao Phraya Basin was expected to receive 400-450 cu m/sec.

The RID saw it necessary to release between 1,000 and 1,300 cu m/second downstream from the dam.

The increased discharge was expected to raise river levels by 0.5-1.5 metres above current levels. Low-lying areas outside flood embankments in Ayutthaya province, particularly in Sena, Phak Hai, Bang Ban, Phra Nakhon Si Ayutthaya, Bang Pa-in and Bang Sai districts, may experience higher water levels.

The RID said the rise was not expected to affect residential areas. However, if water from upstream increases and pushes the flow through the dam above 1,300 cu m/sec, further warnings would be issued.

Currently, the flow at station C.2 in Muang district, Nakhon Sawan, was about 1,400 cu m/sec.

At the Chao Phraya Dam in Sapphaya district of Chai Nat province, the water level upstream was 16.79 metres above mean sea level, and downstream 11.07 metres. The water level was currently 5.27 metres below the riverbank.

The dam is releasing water at a rate of 990 cu m/sec. To ensure preparedness for the evolving water situation, the RID advised authorities in all 11 provinces within the Chao Phraya River Basin, agencies and residents along both banks of the Chao Phraya and Noi rivers, to closely monitor water conditions and follow official updates.