The Flood Forecasting Division has made a preliminary assessment that a sudden flood in the Budhi Gandaki River may have occurred after a landslide temporarily blocked the river before the accumulated water broke through.
Issuing a statement on Sunday, the division said that the flood may have occurred when the landslide-dammed river burst through the blockage.
The division noted that only scattered rainfall had been recorded in the area over the previous 24 hours, making rainfall an unlikely immediate cause of the sudden flood.
Based on preliminary information and an examination of satellite images, the division suspects that the landslide blocked the river before the obstruction gave way, triggering a sudden surge of floodwater.
The division said that a detailed technical analysis is underway to establish the actual cause of the incident.
According to the division, the water level at the Budhi Gandaki-Aarughat flood monitoring station was 2.28 meters at 6:30 a.m. on Sunday.
The level subsequently rose to 5.01 meters at 7:50 a.m. The warning level at the station is 4.50 meters, while the danger level is 5 meters.
Although the water level fell slightly afterward, it began rising rapidly again.
The division reported that the water level reached 6.22 meters at 8:30 a.m. and surged to 8.43 meters by 8:40 a.m.
Immediately afterward, the flood swept away the monitoring station along with a bridge, preventing officials from obtaining further water-level readings, the division noted in its statement.
The division said that it sent early-warning text messages to residents living along the Budhi Gandaki River corridor up to Benighat as soon as it received initial information about the flood at 6 a.m.
At around 8 a.m., it shared additional information through a Facebook Live broadcast, urging residents of vulnerable settlements along the river to evacuate. It also called for traffic on highways and river corridors to be suspended where necessary.
The division urged people to remain highly alert as far downstream as Mugling and also called for precautions in potentially affected areas of Tanahun, Chitwan, and Nawalparasi.
At 9:25 a.m., the division sent another round of SMS alerts, urging members of the public and relevant authorities to move to safe locations and remain there until further notice.
According to the division, approximately 200,000 SMS messages were sent in two rounds.
The division has urged residents in riverside and downstream areas of the Budhi Gandaki River to remain in safe locations, away from riverbanks and vulnerable settlements, until Sunday evening.
It warned that although the river's flow appears to have subsided, the risk remains. It advised the public to avoid crossing bridges or traveling on hazardous roads and to follow instructions issued by local administrations and security agencies.
The division said that it would publish further updates on the flood situation and the findings of its ongoing technical analysis.
