The government has formed a seven-member expert committee to determine the actual origin, causes, and sequence of events behind the devastating flood in the Bhotekoshi-Trishuli river system.
The Ministry of Energy, Water Resources, and Irrigation formed the committee on Wednesday under the coordination of Devesh Belbase, an expert on water policy and governance.
The committee members are hydrologist Narendra Man Shakya, glaciologist Rijan Bhakta Kayastha, remote-sensing expert Uttam Babu Shrestha, geologist Meghraj Dhital, hydropower infrastructure expert Hari Pandit, and disaster-risk reduction expert Anil Pokharel.
According to ministry spokesperson Mohan Kumar Shakya, the committee will conduct field studies from the potential origin of the flood through the Bhotekoshi/Lhende river system to the downstream areas.
Drones, satellite imagery, and other technologies will be used as necessary during the study.
The ministry said that it will study the event not simply as a case of extreme rainfall or flooding, but as a “cascading disaster” in which Himalayan, geological, and hydrological hazards may have been activated sequentially.
A preliminary study by Center for Hydrology and Water Resources Research earlier pointed out that there was still insufficient scientific evidence to establish where the flood originated, what physical processes triggered it, and how those processes spread downstream through the Bhotekoshi-Lhende river system.
The center recommended a comprehensive scientific investigation of the entire sequence of events before attributing the disaster conclusively to climate change.
Report due in two months
The ministry has given the expert committee two months to complete its study.
According to spokesperson Shakya, the investigation will cover not only the flood’s scientific origin and sequence of events but also how hydropower and other energy infrastructure can be protected from similar disasters in the future.
Drawing lessons from the damage to energy infrastructure, the committee will recommend measures for risk preparedness and ways to maintain electricity generation and system operations even during natural disasters.
Following the study, the ministry plans to determine the nature and origin of the event based on available scientific evidence and assign the flood an appropriate scientific name.
Investigation in three phases
According to the ministry, the study will be conducted in three phases.
In the first phase, the committee will examine the chronology of events and physical damage in areas from the high Himalayan region through the Bhotekoshi/Lhende river system and downstream areas.
It will examine the interrelationship between glaciers, rock and soil-slope instability, landslides, debris, river flow, and flooding.
In the second phase, the committee will identify the immediate and underlying physical causes of the flood.
In potential source areas, the team of experts will study rock conditions, cracks, weak geological formations, slope stability, the possibility of landslides, and the amount and characteristics of sediment that entered the river.
In the third phase, the committee will scientifically assess the extent to which human-induced climate change contributed to the likelihood or intensity of these hazards or helped create the conditions preceding the event.
This will involve analyzing rainfall, temperature, snowfall, melting of snow, river flow, and long-term weather and climate trends before the event.
Search for a full chain of events
The ministry said that the committee will investigate whether the disaster was caused by a single factor or whether a process that began in the high Himalayan region triggered a chain of interconnected processes that ultimately developed into a major flood.
The investigation will examine, in an integrated manner, possible processes including changes in the high Himalayan region, instability of rocks or ice-rock masses, mass movements, sediment entering the river, and mixed flows of water and sediment.
In particular, the committee will study the size, area, volume, and weight of rocks that may have fallen in the potential source area, how much material fell, and the possible reasons for the collapse.
Data from China to be sought
The ministry also plans to incorporate scientific and hydrological information available from the Chinese side into the investigation. Where necessary, mechanisms for scientific cooperation and data sharing will be developed.
A World Weather Attribution study of the extreme rainfall, floods, and landslides that occurred in Nepal from September 26-28, 2024, had previously pointed to effects associated with human-induced climate change.
However, the current event may have been different in nature, so it will not be directly compared with the 2024 disaster, the ministry said. Instead, the investigation will be based on evidence specific to the new event.
