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 from the North.

Floods, the worst in 50 years, have already caused widespread damage in Chom Thong district of  Chiang Mai which has been hit by heavy rain.

Some 237 households in seven provinces -- Chiang Mai, Chiang Rai, Lamphun, Tak, Lampang, Mae Hong Son and Kanchanaburi -- have been badly affected by flooding.

The 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 flooding.

Floodwater flowing from the North could cause levels in the Chao Phraya River in Chai Nat and Ayutthaya to rise by 1.5-2 metres.

Irrigation Office Region 12 would control water levels and prevent harm to agricultural fields.

After experiencing flash floods over the past few days, Chom Thong district has seen water levels finally drop.

A northwestern monsoon has brought heavy rain and thunderstorms to the northern and upper northeastern regions as well as many other parts of the country.