Over 18,500 families have moved to high grounds from low-lying areas in five northern districts along the Teesta basin where a red alert was issued on Wednesday afternoon after a flash flood in the upstream across the border in India washed away parts of a dam. The breaching of the Chungthang dam, built at the confluence of the glacier-fed rivers – the Lachung and the Lachen, in the Mangan district of Sikkim, where the Teesta rises, caused the waters to suddenly rise by up to 20 feet leading to destruction of life and property downstream, Indian media reported citing the Central Water Commission and India Meteorological Department.
At least 23 Army personnel were washed away while the raging Teesta water swept away sections of the national highway and local roads and bridges as well, including a steel bridge, severely impacting connectivity in north Sikkim. The flash flood was triggered by a cloudburst, an extreme amount of precipitation over a short period of time, over Lhonak Lake, a lake located 5,200 m above the sea level in the Himalayas, in the early hours of Wednesday.
‘An estimated volume of 7,000 cusec water is rushing towards Bangladesh, enough to raise the Teesta by about 5 feet,’ said Udoy Raihan, executive engineer, Flood Forecasting and Warning Centre. The Teesta flowed 5 cm above the danger mark at 4:00pm at the Dalia station, following an 82 cm or 2.6 feet swelling in its water level since Wednesday noon, according to the WDB.
The Teesta will remain highly volatile, rapidly rising and falling through the early hours of Thursday, the WDB warned. The sudden rise in the Teesta water level brings to mind the massive amount of water passed through the river on October 20, 2021, setting an all-time record of water level in the river. In a special bulletin issued at 4:22pm on Wednesday, the FFWC said that the water level at the Gajaldoba barrage in India increased by 2.85 metre overnight and 1.12 metre at Domuhani because of the damage in the Chungthang dam. The water level at Dalia might rise 50 cm above the danger mark, the FFWC said, while the water level at Kaunia might cross the danger mark today.
The northern districts of Rangpur, Kurigram, Lalmonirhat, Nilphamari, and Gaibandha might witness flood persisting through the weekend because of potential heavy rain over Sikkim over the next 48 hours, the FFWC said quoting IMD. This was the ninth time the water level at Dalia crossed the danger limit since June, each time because of arbitrary release of water through the Gajaldoba barrage by India.
‘All 54 floodgates at the Gajaldoba have been opened,’ said superintendent engineer Ahsan Habib. ‘A record amount of water might pass through the river,’ he said. On Wednesday, authorities sent teams to inform people in chars and low-lying areas along the Teesta bank about the imminent danger. Authorities claimed to have covered 165 km areas with their announcement of the imminent disaster.
‘More than 18,500 people have moved to shelters on high grounds to flee the flooding,’ said Habibur Rahman, divisional commissioner, Rangpur. This is the second spell of flood to hit northern districts since September 25, when a cloudburst, particularly inside Bangladesh, led to sudden rise in rivers in the area. Some northwestern districts also experienced days of flooding in September due to heavy rain in the upstream. ‘I have run out of my options to flee from so frequent flooding,’ said Jahir Mia, 55, a resident of Isli at Gangachara in Rangpur, sitting in his temporary house on the embankment.
Jahir Mia has lost his place of living twice already this year. His family of seven people are literally displaced by flooding. Bangladesh Meteorological Department predicted heavy rain in places over the country over the 48 hours starting at 12:00pm on Wednesday. The heavy rainfall might cause landslide in Chattogram division, the BMD said in a warning. In the 24 hours until 6:00pm on Wednesday, Bangladesh’s highest maximum rainfall of 112mm was recorded in Patuakhali. ‘Heavy rain might continue in parts of Bangladesh through the weekend,’ said Monowar Hossain, meteorologist, BMD.
The maritime ports have been asked to hoist signal number three until further notice and fishing boats have been asked to stay close to the shore because of deep convection due to strong monsoon in the north Bay of Bengal. In the 24 hours until 8:30am on Wednesday, Bihar received 571 per cent excessive rainfall, followed by West Bengal receiving 466 per cent excessive rainfall, Sikkim 376 per cent excessive rainfall, Assam 200 per cent excessive rainfall and Arunachal Pradesh 50 per cent excessive rainfall, reported the IMD.
With regard to cumulative rainfall since October 1, Bihar witnessed 409 per cent excessive rainfall, followed by 334 per cent excessive rain recorded in the West Bengal, 129 per cent excessive rainfall recorded in Sikkim, 106 per cent excessive rain recorded in Assam and 38 per cent excessive rain recorded in Mizoram. There is a forecast of extremely heavy rainfall in places of Assam and Meghalaya today.