Landslide rockfall risk assessment
Landslide rockfall risk assessment
 
 
 

In assessing landslide and rockfall risk, we characterise hazard, exposure and vulnerability through field mapping and remote sensing, analysis of past events, modelling of current and future scenarios, and through detection and monitoring the behaviour of any ongoing instabilities. The outputs of those activities lead to hazard and risk maps, and design for mitigation and prevention measures, such as early warning systems.

 
 

In mountainous terrain, landslides can lead to the damming of mountain rivers, creating a range of high risk scenarios impacting downstream villages and infrastructure. This occurred in the early hours of August 2 2014, when the Jure Landslide in Sindhupalchowk Nepal failed, with an estimated volume of 1’000’000 m3. Approximately 2 km of the major transit route between Nepal and China was buried, along with two villages, taking the lives of 156, injuring 27 and displacing 436 people.

 
 

As a result of the landslide, the Sunkosi river was dammed forming a lake, which extending 3 km upstream. The lake inundated sections of a main highway and a number of houses.

 

 
 

The lake dam, was artificially breached by the Nepalese army, providing a freeboard of 20 metres. Later, the dam breached naturally, reaching a depth of 47 metres.

 

 

 
 

Breaching of the landslide dam, lead to an increase in sediment deposition, thereby damaging and rendering a downstream hydro power facility inoperable. The landslide dam breach resulted in a river base-level elevation increase of 20 metres.

The Jure landslide is the focus of study for sustainable mitigation and prevention measures.