The department confirmed that the death toll from the floods rose to 30 as of Friday morning - 11 in Surin, nine in Si Sa Ket, five in Prachin Buri, two each in Nakhon Nayok and Yasothon, and one in Sa Kaeo.
Official figures obtained from residency rolls listed the following as damaged by the floodwaters: 14,703 houses, 2,168,466 rai of farmland, 4,947 roads, 201 bridges, 218 schools, 325 temples and 56 state office buildings.
In Nakhon Ratchasima, floods had hit more than 200 households after more than five million cubic metres of water has been released from the full Lam Chiang Klai reservoir. The reservoir has a capacity of 27 million cubic metres of water but it held as much as 35 million cubic metres as of Friday morning.
In Ubon Ratchathani and Si Sa Ket, more than 15,000 people were moved to higher ground for their safety.
The department issued a warning of heavy rain over the next few days in Kanchanaburi, Ratchaburi, Petchaburi, Prachuap Khiri Khan, Chon Buri, Rayong, Chanthaburi, Trat, Ranong, Phang Nga, Chumphon, Surat Thani and Phuket.
Meanwhile, City Hall's flood prevention centre reported that about 80% of Bangkok and nearby provinces would get rain throughout Friday.
Many areas of the capital had seen heavy rain since Thursday night. Main roads, such as Phahon Yothin, Kaset-Navamin, Lad Prao, Rama IV, Chaeng Wattana and Ngam Wong Wan, were flooded, causing traffic congestion.
The flood prevention centre said there would be heavy rain in some areas of Bangkok during the day.
Bangkok Governor Sukhumbhand Paribatra said more than 850 households in 25 communities could be hit by flooding as water levels in the Chao Phraya river are expected to increase in the middle of this month.
The governor said water levels could rise by two metres above sea level on Oct 15 and 16 due to water run-off from the North.
Flood walls stretching more than 86 kilometres along the river banks should be completely built by 2014, he said.
A survey conducted by Bangkok Poll shows that 54% of respondents are concerned that floods would hit the capital again this year, though the situation would not be as critical as it was in 2011.
Bangkok University pollsters based their conclusions on a survey of 1,190 people living and working in the city.
A total of 48.7% of respondents said reports on flooding in several provinces have made them increasingly concerned about possible floods in Bangkok.
The government has said that Bangkok would likely be spared from major flooding this year, and said a repeat of the massive flooding of 2011, in which 813 people were killed nationwide and economic losses topped 40 billion US dollars, was unlikely.