Glacial break or natural dam collapse likely cause of Tibet-Nepal floods, expert says
The devastating flash floods and massive landslides that recently swept through regions of Tibet and Nepal were likely caused by the catastrophic failure of a glacial lake natural dam, triggered by a sudden ice-rock avalanche, according to a leading Thai geotechnical expert.
Assoc. Prof. Dr. Suttisak Soralump, head of the Geotechnical Engineering Research and Development Center (GERD) at Kasetsart University, posted an analysis of the disaster on his Facebook page today, disaster, stating that the initial surge of water was exceptionally high, rapid and powerful, exhibiting characteristics consistent with a sudden structural breach rather than typical wild forest runoff.
"The pattern of the water flow strongly resembles a dam breach," Dr. Suttisak explained. In the absence of the failure of a manmade dam in the region, he indicated the likely culprit was the collapse of a natural dam, a glacial lake breach or a compounded combination of both events.
A landslide dam forms when heavy rainfall, earthquakes or collapsing steep icy slopes force a mixture of soil, rock, water and ice down into V-shaped mountain valleys, blocking natural streams.
As meltwater from upper glaciers accumulates behind this natural obstruction, it forms a high-altitude reservoir known as a glacial or landslide lake.
Unlike engineered dams, these natural barriers lack compaction, filtration systems and spillways, making them inherently unstable and prone to sudden collapse without prior warning.
Dr. Suttisak added that the collapse may have been triggered by a sudden ice-rock avalanche plunging into the accumulated lake. The resulting displacement wave would have overtopped and destroyed the barrier, releasing a massive volume of water in a phenomenon known as a Glacial Lake Outburst Flood (GLOF).
In some terrains, a primary breach can trigger a domino effect, destroying multiple natural dams further downstream in a devastating cascade failure.
Because these natural dams often form at extreme altitudes, the rushing water gains tremendous momentum and destructive energy as it hurtles down into lower-lying valleys.
Crucially, Dr. Suttisak highlighted that such breaches do not require active rainfall to occur.
"The failure of a landslide dam or lake can happen at any time, even on a bright day without rain," Dr. Suttisak stated, describing the phenomenon as a "sunny day failure."