This document summarizes research on modeling landslide-triggered tsunamis in alpine lakes. The researchers tested several numerical schemes on benchmark problems and additional tests simulating landslides. The LF scheme was best, being non-oscillatory. A case study applying the LF scheme to a hypothetical landslide in a confidential alpine lake was presented. 1D and 2D modeling showed wave heights comparable to other methods. While results were promising, wet-dry transition and coupling with landslide modeling need further work. The researchers aim to calibrate the model on known cases and develop a two-phase model for a comprehensive landslide-tsunami simulation system.

1. Vajont 1963-2013 International Conference
Dams, landslides and their natural environment
Landslide-Triggered Tsunami
Modelling in Alpine Lakes
M. Franz, Y. Podladchikov, M. Jaboyedoff, M.-H. Derron
Université de Lausanne CRET - ISTE
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2. Outline
• Introduction
• Methodology
–
–
–
–
Toro tests
Additional tests
Resolution test in 2D
Synthesis
• Case study
–
–
–
–
Context
Slide characteristics
Wave modelling
Comparison
• Conclusion - Perspectives
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3. INTRODUCTION
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4. Environmental context
Alpine region
o Population
o Lake
o Slope
Necessity to
assess this Risk
Predictive model
(Google earth, NASA, 2012)
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5. Modelling context
• Generally applicable equations from model tests
(Slingerland & Voight, 1979; Wieczorek et al., 2003; Heller et al., 2009)
Useful for a first approach
Qualitative approach of the bathymetry
• Shallow water equations (SWE)
(Wieczorek, 2007; Gonzalez-Vida et al., 2011; Pudasaini & Miller, 2012)
Comprehensive method (bathymetry)
Numerical artefacts (on real bathymetry)
Problems with wet to dry bed transition
• 3D
(Lynett & Liu, 2004; Zijlema & Stelling, 2008; Ward & Day, 2011)
Most accurate method
Great computational power required (supercomputing)
We choose the models based on SWE
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6. METHODOLOGY
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7. The numerical schemes
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8. Tests
• 5 tests from Toro (2001)
– Build for dam break problems
• 3 additional tests
– For wave generated by landslide
– For application to real bathymetry
• 2D resolution test
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9. Toro tests
5 tests from Toro (2001)
– Left critical Rarefaction
and Right Shock
– Two rarefaction and nearly
dry bed
– Right dry bed Riemann
problem
– Left dry bed Riemann
problem
– Generation of a dry bed
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10. Toro tests
5 tests from Toro (2001)
– Left critical Rarefaction
and Right Shock
– Two rarefaction and nearly
dry bed
– Right dry bed Riemann
problem
– Left dry bed Riemann
problem
– Generation of a dry bed
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11. Toro tests
5 tests from Toro (2001)
– Left critical Rarefaction
and Right Shock
– Two rarefaction and nearly
dry bed
– Right dry bed Riemann
problem
– Left dry bed Riemann
problem
– Generation of a dry bed
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12. Toro tests
5 tests from Toro (2001)
– Left critical Rarefaction
and Right Shock
– Two rarefaction and nearly
dry bed
– Right dry bed Riemann
problem
– Left dry bed Riemann
problem
– Generation of a dry bed
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13. Toro tests
5 tests from Toro (2001)
– Left critical Rarefaction
and Right Shock (ZOOM)
– Two rarefaction and nearly
dry bed
– Right dry bed Riemann
problem
– Left dry bed Riemann
problem
– Generation of a dry bed
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14. Toro tests
5 tests from Toro (2001)
– Left critical Rarefaction
and Right Shock (ZOOM)
– Two rarefaction and nearly
dry bed
– Right dry bed Riemann
problem
– Left dry bed Riemann
problem
– Generation of a dry bed
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15. Toro tests
5 tests from Toro (2001)
– Left critical Rarefaction
and Right Shock (ZOOM)
– Two rarefaction and nearly
dry bed
– Right dry bed Riemann
problem
– Left dry bed Riemann
problem
– Generation of a dry bed
LF & Gup non oscillatory
Selected for further tests
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16. Additional tests
3 additional tests for
Landslide – generated
Tsunami
– Moderate test of landslide
penetration
– Extreme test of landslide
penetration
– Rough bed
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17. Additional tests
3 additional tests for
Landslide – generated
Tsunami
– Moderate test of landslide
penetration
– Extreme test of landslide
penetration
– Rough bed
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18. Additional tests
3 additional tests for
Landslide – generated
Tsunami
– Moderate test of landslide
penetration
– Extreme test of landslide
penetration
– Rough bed
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19. Resolution test in 2D
• LF scheme
• Circular dam break
Experiment
2D Wave prop.
2D Wave prop.
CPU time
[s]
200
2500
GPU time
[s]
4
500
Ratio
GPU-CPU
50
50
Resolution
1280x 1280
6400 x 6400
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20. Synthesis
• All the schemes successfully passed the tests
• LF and GUP are the best solutions because they are
not oscillatory
• The diffusive problem of LF decrease with the
increase of the resolution
• The run time rise with the resolution but is
compensated by the use of GPU computing
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21. CASE STUDY
(CONFIDENTIAL SITE)
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22. Context
(Swisstopo)
(Swisstopo)
(SIG, 2012)
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23. Slide characteristics
• Geometry :
–
–
–
–
–
Length: 100 m
Width: 250 m
Max. depth: 15 m
Volume: 200’000 m3
Velocity: 5 m/s
(CSD, 2012)
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24. Wave modelling
• 1D modelling with LF
– Dam
– Dike
• 2D modelling with LF
• Comparison of the wave height between different
methods
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25. Wave modelling
• 1D – Dam
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26. Wave modelling
• 1D – Dyke
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27. Wave modelling
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28. Wave modelling
(Swisstopo)
• 2d
(Swisstopo)
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29. Comparison
• Equations from model test
– H3 (ICOLD, 2000)
– Hmax (Kamphuis & Bowering, 1970)
– wh3d, wr3d (Heller et al., 2009)
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30. CONCLUSION PERSPECTIVES
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31. Conclusion
• Model
– LF scheme can be the method of choice because:
•
•
•
•
Non-oscillatory
Diffusivity disappear with high resolution
Withstands rough beds
Simple
• Case study
– No (major) numerical artefacts or instabilities detected
– Handle real topography
- Validated with other methods
But
- Do not manage the wet-dry transition yet
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32. Perspectives
• Calibration on well known cases
• Coupling LF with Gup to handle wet-dry transition
• Two-phases model development for a fully
comprehensive system
–
–
–
–
–
Landslide propagation modelling
Interaction between landslide and water
Propagation of the impulse wave through the water body
Erosion of the landslide dam (in case of overtopping)
Erosion of the river banks (in case of downstream flood or
outburst)
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33. Thank you for your attention
Grazie
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