The floods which have submerged parts of the kingdom are expected to subside by the end of next month, according to the Office of National Water Resources (ONWR).
ONWR secretary-general, Surasee Kittimonthon, said rainfall is expected to decrease gradually across the North, Northeast and Central Plains at the start of next month, which marks the beginning of the dry season.
In some parts, rainfall is already dropping. Due to steadily decreasing rainfall, authorities have been able to cut the water discharge rate from the Chao Phraya barrage in Chai Nat, which controls the amount of water flowing into the Central Plains from the North.
Similarly in the Northeast, authorities have reduced the water discharge rate at Khon Kaen’s Ubolratana Dam. The dam overflowed recently, causing widespread damage to homes and farmland. The ONWR will be assisted by the National Water Command Centre (NWCC) in managing the water discharge rate across the nation’s major dams and waterways, Mr Surasee said.
Meanwhile, heavy machinery has been deployed to reinforce vulnerable embankments and dredge clogged waterways, to help drain water from flooded areas. Average rainfall between January and October was 17% higher compared to the same period last year — about 1% below levels seen during the great floods of 2011.
The ONWR will coordinate with the NWCC at least three days before any decision to increase the dam’s discharge rate is taken, to minimise flood damage in provinces downstream of the Chao Phraya barrage.
This will ensure people have enough time to prepare, as most floodwalls in downstream provinces were only built to withstand discharge rates of up to 2,500m³ per second, Mr Surasee said.
As the water discharge rate from the Chao Phraya barrage in recent weeks has exceeded that figure, some communities were submerged. At its peak this year, around 3,180 cubic metres (m³) of water per second passed through the Chao Phraya barrage, still lower than 3,600m³ per second rate seen in 2011.
When asked why floods took place this year in areas which have never had flooding issues in the past, Mr Surasee blamed rapid changes in land use and obstructions in waterways.
When rainfall starts to drop in the coming weeks, authorities will further cut the water discharge rate from the Chao Phraya barrage.
The rate will be further decreased to around 1,200m³ per second on Nov 20, and further to 700m³ per second about a week later, Mr Surasee said, noting the drop in water levels will allow flood waters affecting the rice fields in Chai Nat, Sing Buri, Ang Thong and Ayutthaya to drain to the Noi River and other waterways.
The government has set aside 6 billion baht to compensate two million households hit by this year’s floods. Each family stands to receive about 3,000 baht.