The Royal Irrigation Department (RID) on Sunday issued a flood warning for seven provinces in the Chao Phraya River basin as large volumes of water are flowing downstream from the North.
Floods, the worst in 50 years, have already caused widespread damage in Chom Thong district of the northern province of Chiang Mai which has been lashed by heavy downpours.
According to the Disaster Prevention and Mitigation Department, 237 households in seven provinces -- Chiang Mai, Chiang Rai, Lamphun, Tak, Lampang, Mae Hong Son and Kanchanaburi -- have been badly affected by flooding.
Krisada Sripermpan, director of Irrigation Office Region 12, sent a warning letter to seven governors in Chao Phraya basin provinces -- Chai Nat, Uthai Thani, Sing Buri, Ang Thong, Suphan Buri, Ayutthaya and Lop Buri -- to closely monitor the flood situation and inform people of possible inundation.
Floodwater flowing from the North through the Chao Phraya barrage could increase to 300-500 cubic metres per second, causing levels in the Chao Phraya River in Chai Nat and Ayutthaya to rise by 1.5-2 metres.
However, Mr Krisada said Irrigation Office Region 12 would control water levels and prevent harm to agricultural fields. The office will issue a flood alert if water flow through the barrage reaches more than 500 cubic metres per second.
Kriangkrai Chaipiset, chief of Doi Inthanon National Park in Chiang Mai, said the park has closed public access to waterfalls and tourism spots due to the possibility of flash floods and landslides. The heaviest rainfall in Doi Inthanon in 50 years -- 200 millimetres -- was recorded at Kew Mae Pan Nature Trail.
After experiencing flash floods over the past few days, Chom Thong district has seen water levels finally drop.
The situation in four villages in tambon Khuang Pao, which also has endured heavy flooding, is likewise improving.
A northwestern monsoon as well as low-pressure cells moving eastward have brought heavy rain and thunderstorms to the northern and upper northeastern regions as well as many other parts of the country.