Avalanche at 5,500 metres set off Gorkha's Budhi Gandaki flood, NDRRMA report finds

Nepal's disaster authority says a chain reaction high in the Himalaya, not a single landslide, triggered the flood of Sunday, October 11, on the Budhi Gandaki River in Gorkha district.

A technical report by the National Disaster Risk Reduction and Management Authority, Nepal's disaster agency, NDRRMA, found an avalanche struck at about 5,500 metres near the headwaters of the Ungilung Khola, between Chamar Himal and Syerangi Himal, in Chumnubri Rural Municipality-6, OnlineKhabar English reported. The avalanche happened around 4:20 am on October 11, triggering a massive landslide that carried snow, water and debris downstream, the report found.

For families in Gorkha, five people were missing in NDRRMA's October 11 count. Two women and three men were staying at a sheepfold in Ungiling, Chumchet, NDRRMA said on October 11, The Himalayan Times reported. The flood came about 45 days after the Bhotekoshi disaster, roughly 40 kilometres away, Nagarik News reported.

The Department of Mines and Geology estimated the landslide released energy equal to a magnitude 3.5 earthquake, the NDRRMA report said. Debris piled up where Ungilung Khola meets Syar Khola, briefly damming the river before it broke through. The flood first reached Salleri at about 4:30 am and peaked at about 6:30 am, at an estimated 20 to 25 metres, the NDRRMA report said. It swept away the main camp of the 341 megawatt Budhi Gandaki Hydropower Project, The Himalayan Times reported, citing NDRRMA. Buildings in Jagat and concrete bridges over Soti Khola and the Budhi Gandaki River were also damaged, the NDRRMA report said.

An independent reading by researcher Dr Santosh Nepal, reported by Nagarik News, broadly agrees. His preliminary reading suggests a glacier or ice mass breaking off the southern face of the 7,100 metre Chamar Himal and falling into the Syar River. But he said the exact trigger is not yet confirmed and needs sharper satellite images. He said it shares traits with the Bhotekoshi flood, both tied to ice and rock breaking loose high in the Himalaya.

The Nepali Army says it has rescued 186 people, including 31 foreign nationals, by helicopter and other means from Filim, Chumling, Aarughat, Dovan, Wihi, Lakpal, Salleri, Uhiya and Kerunga since the flood struck, The Rising Nepal reported.

In Dharche Rural Municipality, the road to Jagat village remains cut off. "The road from Phalambesi towards Jagat is closed. There is not even a path for people to walk, let alone vehicles," said Laxman Gurung, ward chair of Dharche-3, Republica reported. He said displaced families are staying with relatives or in nearby homes. Authorities have not yet set up holding centres, which need drinking water, toilets, electricity and cooking arrangements before they can open, he said.

The official counts

NDRRMA's October 11 press note listed five people missing and 47 rescued, The Himalayan Times reported. No deaths or injuries had been confirmed in preliminary reports, The Kathmandu Post reported on October 11. The Nepali Army's own count, reported separately by The Rising Nepal, puts the number rescued since the flood at 186, including 31 foreign nationals. The two figures come from different agencies counting at different times and are not directly comparable. Narayan Prasad Sapkota, the administrative chief of Chumnubri Rural Municipality, estimated that 35 to 40 houses were swept away in Jagat Bagar, Salleri and Ghattikhola, The Kathmandu Post reported.

What we still do not know

The government plans to amend the law so missing people can be declared dead after 45 days, OnlineKhabar English reported. Whether it covers Gorkha's missing is a question for the Home Ministry.

How many households remain displaced with no holding centres, and when water, power and toilets will reach them, is a question for the Gorkha District Administration Office.

What the flood cost the Budhi Gandaki Hydropower Project, and whether it delays construction, is a question for its developer and the Ministry of Energy.