The Royal Irrigation Department on Sunday issued a flood warning for provinces in the Chao Phraya river basin as more water will be discharged from the Chao Phraya Dam from Monday.
The amount of water running past Nakhon Sawan on Sunday was 903 cubic metres per second.
Combined with rainwater and discharge from the Sakaekrang River in Uthai Thani, it was believed the total volume of water running down to the Chao Phraya Dam in Sapphaya district of Chai Nat province would be 1,300-1,400 cubic metres per second on Sunday.
From Monday the dam is set to increase the amount of water discharged into the Chao Phraya to between 800 and 1,200 cubic metres per second, consequently raising the water level in the river below the dam.
In Ayutthaya province, the water level in Bang Ban, Sena and Phak Hai districts was expected to go up by about 1.50 metres.
The Royal Irrigation Department said it would carefully regulate water through the Chao Phraya Dam to prevent damage to farmland on both sides of the river.