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How LDOF occurs

Short answer

A landslide dam outburst flood occurs when a landslide blocks a river, forming a loose debris dam. Water impounds upstream and eventually the dam fails by overtopping, piping, or slope collapse, releasing a destructive flood wave that can erode its bed and grow downstream.

How does a landslide dam outburst flood (LDOF) occur?

A landslide dam outburst flood (LDOF) is the sudden flood produced by the failure of a natural dam formed when a landslide blocks a river.

How it occurs

  1. A large landslide, rock avalanche or debris flow (triggered by heavy rain or an earthquake) falls into a narrow river valley and blocks the river, forming a dam.
  2. Water accumulates upstream and forms a lake.
  3. The dam is made of loose, unsorted, poorly compacted material and has no spillway.
  4. The dam fails by overtopping and erosion, piping/seepage, or sudden slope collapse. Failure may occur within minutes to months, sometimes years.
  5. A large volume of water and debris is released as a destructive flood wave that travels downstream and may grow by eroding its bed and banks.
   landslide
      \\  
  =====\\|dam|------> breach
  river  [lake]         flood wave

Examples: the 2014 Jure (Sunkoshi) landslide dam and the landslide dams formed after the 2015 Gorkha earthquake.

✓ Answer checked by Claude Opus 5.5 (high effort)

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