The La Nina climate pattern has begun affecting local weather, according to the Thai Meteorological Department. Although there is heavy rainfall in some areas, officials say water volume in the reservoirs of major dams may not be sufficient to meet requirements during the dry season that runs from November to April.
Thailand began experiencing La Nina in July and the pattern is likely to continue until early next year, the department’s weather forecasters say. It will lead to heavy rainfall across the country, alongside tropical storms in August and September.
Cumulative rainfall from May 20 to Aug 1 was up by 15% compared to the same period last year and caused flooding in 37 provinces. Some parts of 12 provinces are under water, with the hardest-hit being Chachoengsao, Chiang Rai, Chiang Mai, Kalasin, Roi Et, Ubon Ratchathani and Yasothon.
This year’s La Nina will not be as severe as expected earlier, thanks to factors such as air pressure patches and monsoon troughs, said Paitoon Kengkarnchang, deputy secretary-general of the Office of the National Water Resources (ONWR), citing information from the National Hydroinformatics Data Center.
Despite expected heavy rain from August to October in some areas of the Lower North, Central Plains and the West, there are concerns that water supplies will not be enough for the dry season.
Rainfall often misses the reservoirs of some major dams, including Bhumibol and Sirikit, which currently have low water levels.
However, he said two other major dams, Srinakarin and Vajiralongkorn, are expected to benefit from La Nina, as they will receive a large volume of water from recent rainfall that replenished the Mae Klong River.
The water from these dams will be used locally as well as to supply the Tha Chin River basin and Bangkok, he said.
Mr Paitoon said authorities have discharged water from the Chi and Mun rivers in the Northeast to prepare for more rainfall.
He added that the Office would assess the situation to ensure dams have sufficient water for the upcoming dry season.
In a related development, water from the Mekong River was reported to have submerged Sawan Chai Khong Road in Muang district of Nakhon Phanom province on Thursday.
Water overflowed into fishing shelters and agricultural fields over a one-kilometre distance, to a depth of 40-50 centimetres, making travel along the route difficult.
The Department of Disaster Prevention and Mitigation has warned local residents about continuous heavy rainfall in the northern region and Laos, suggesting that water levels in the Mekong River be closely monitored.