Devastating 2011 flooding could return this year - expert

The devastating flooding in Bangkok and several central provinces in 2011 may be repeated this year if four factors fall or fail to fall into place, Dr Sonthi Kochawat, an expert in the environment and health, wrote in his Facebook post today.

The first factor is the huge volume of water flowing into the Chao Phraya River from the northern region, forcing irrigation officials at the Chao Phraya Reservoir in Chainat to release an average of nearly 3,000 cubic metres of water per second (m3/s), causing flooding downstream in Sing Buri, Ang Thong and Ayutthaya.

If the water flowing through the pumping station at Bang Sai exceeds 2,500m3/s, the Chao Phraya River water level in Pathum Thani, through Nonthaburi to Bangkok, will rise by one metre.

Thailand is usually sees at least one tropical storm or depression in September through October. If there is continuous heavy rain, dubbed a “rain bomb”, there is an increased likelihood of flooding.

The third factor would be excessively high tides in October. If water in the swollen Chao Phraya River cannot drain into the Gulf, via the estuary and a network of canals, the period of flooding will be prolonged.

The last factor is water management, prior to the arrival of the mass of water from the north. This includes preparatory dredging of canals, reinforcing embankments and proper management of discharges through the Chao Phraya Dam in Chainat.

Meanwhile, Caretaker Prime Minister’s Office Minister Jakkapong Sangmanee said that initial assessments show that the volume of water anticipated this year will not reach that of 2011 adding, however, that the Meteorological Department will be asked to provide feedback to ensure more accurate and updated information about water volumes and rainfall.

Meanwhile, the Department of Public Disaster Prevention and Mitigation is coordinating with ten central provinces, from Uthai Thani to Bangkok, to monitor the water situation in the Chao Phraya River closely, especially in low-lying areas unprotected by flood walls.

Due to the anticipated increased water flow into the upstream reaches of the Chao Phraya River, estimated at about 1,200m3/s, the Royal Irrigation Department has decided to drain 700-900m3/s of water through the Chao Phraya Dam in Chainat province. This will cause the river’s water level downstream, in Ang Thong and Ayutthaya, to rise by 40-80cm from today onward. Riverside communities have not been affected yet, according to the department.