In September and October, Bangkok is at risk of flooding which may be worse than that experienced this week, especially Wednesday night, warned Assoc. Prof. Dr. Seree Supratid, a water expert and director of the Climate Change and Disaster Centre at Rangsit University.

Dr. Seree said that the flooding in Bangkok on Wednesday and Thursday was caused by an unusual amount of rainfall, measured at 160mm in some areas, which is equivalent to the maximum amount in a 10-year cycle, compared to 60mm in a 2-year cycle.

He explained that the 160mm of rainfall for a 10-year cycle was the average rainfall calculated from the amount of rain which fell in the past 50 years and 260mm for a 100-year cycle, adding that this kind of excessive rain can occur any time, citing the downpours on Wednesday night.

Citing information obtained from the Bangkok Metropolitan Administration (BMA), he said that the water levels in Bangkok’s canals increased by about one metre after about two hours of rainfall on Wednesday night which, he admitted, was unusual, noting that the city administration had already drained water out of the canals to increase capacity to store rain water from road surfaces.

He then suggested that the city administration investigate where the problem lies, whether it was the water pumps or the discharge of water into the river, resulting in the heavy flooding.

Dr. Seree praised the BMA’s rain forecasting system, but he said the drainage system failed and needs to be fixed before the flooding anticipated in September and October, which may be more serious due to high tides and water runoffs from the northern region during that period.