Kathmandu, 12 Oct: A preliminary analysis has suggested that a landslide blocked a stream in Chumnubri Rural Municipality-6 of Gorkha District, triggering a sudden flood in the Budhi Gandaki River after the blockage was released.
Shanti Mahat, spokesperson for the National Disaster Risk Reduction and Management Authority (NDRRMA), said a massive landslide occurred between Lokpa and Chumling in Chumnubri Rural Municipality-6. The landslide blocked the Budhi Gandaki River, and when the blockage gave way, a large debris-laden flood swept downstream, causing physical damage.
The Flood Forecasting Division of the Department of Hydrology and Meteorology said an examination of satellite images showed that a landslide had occurred in the area on Saturday evening. Experts have preliminarily suggested that the flood may have been triggered by a temporary natural dam formed when the landslide blocked the river’s flow.
However, the division said a detailed technical investigation is underway to identify the exact landslide location, determine which stream was blocked, and establish how the flood occurred.
According to Binod Parajuli, a senior hydrologist at the Flood Forecasting Division, satellite images indicate that a landslide occurred in Tumje, Chumnubri-6, on Saturday evening.
The issue of geological hazards in Dharche and Chumnubri, areas near the epicentre of the 2015 Gorkha earthquake, has once again come under scrutiny.
Geologist Shiv Kumar Baskota said weak geological formations, steep terrain and narrow gorges increase the risk of landslides blocking rivers and triggering sudden floods.
“It is difficult to predict when a landslide will occur on land fractured by an earthquake,” he said.
“The nature of the flood in Gorkha resembles the landslide that occurred in Jure, Sindhupalchok, several years ago.”
He added that the flood in the Budhi Gandaki River differed from the situation in the Bhotekoshi River.
“In the Budhi Gandaki, a large section of the mountain appears to have collapsed at once, forming a dam. The river was blocked and subsequently reopened, which appears to have limited the damage,” he said.
Tremors Felt Before the Flood
Nima Lama, chairperson of Chumnubri Rural Municipality, said tremors similar to those of an earthquake were felt before the flood struck the Budhi Gandaki River.
“A landslide falling from above the river blocked the Budhi Gandaki. The flood that followed caused damage downstream,” he said.
He added that a major flood had occurred in the same river 25 to 30 years ago, although it was not similar to the recent event.
No seismic measurements were recorded in the area. It is suspected that the ground may have shaken when the landslide occurred.
Technical Teams Deployed
The National Disaster Risk Reduction and Management Authority said a three-member team of geologists, equipped with drones, has been deployed to investigate the cause of the flood in the Budhi Gandaki River.
A separate team, including the director generals of the Department of Roads and the Department of Local Infrastructure Development, has also been deployed to assess road access and the feasibility of constructing a Bailey bridge.
