Volume 29 Issue 7 - September 4, 2015 PDF
Counter
Reflection of Typhoon Morakot – The Challenge of Compound Disaster Simulation
Yu-Shiu CHEN2, Yu-Shu KUO1, Wen-Chi LAI2, Yuan-Jung TSAI1, Shin-Ping LEE2, Kun-Ting  CHEN1Chjeng-Lun SHIEH1,2,*
1 Department of Hydraulic and Ocean Engineering, National Cheng-Kung University, Taiwan
2 Disaster Prevention Research Institute, National Cheng-Kung University, Tainan, Taiwan,
 
Font Enlarge
Climate change has altered how disasters occur. In Taiwan, because of increasing intensity and frequency of extreme rainfall events. The compound disasters can combine small-scale floods, debris flows, shallow landslides, deep-seated landslides, and landslide lakes into a large-scale single disaster event. This commonly occurs when the accumulative rainfall (R) is smaller than 1000 mm with corresponding rainfall intensity (I) greater than 100 mm/hr. On the contrary, if there is a large accumulation of rainfall during a low-intensity rainfall event, deep-seated landslides or landslide lakes tend result. This occurs when the accumulative rainfall is greater than 1000 mm with corresponding rainfall intensity less than 100 m/hr.(Fig.1)

Typhoon Morakot had the largest recorded rainfall duration, lasting a total of 107 hours. Moreover, the maximum hourly rainfall reached 123 mm/hr and the accumulative rainfall reach 3000 mm at Alishan station during the Typhoon(Fig.2). The rainfall with the characteristics of a high-intensity, long duration, and wide range. It caused a compound disaster including five types of disasters in a short time: 56.5 ha of shallow landslide, two debris flow, flooding, deep-seated landslide, and landslide lake(Fig.3).

In the case of Hsiaolin Village, the compound disaster includes landslide, debris flow, deep-seated landslide, landslide dam formation, landslide dam break, and inundation. All of these disasters occurred around Hsiaolin village. In the past, a number of numerical models are developed for single-type disasters. These models focus on the analysis of disaster characteristics. However, in a compound disaster, every single component of these disasters is connected and interrelated. Therefore, a structure of linking simulation models is needed to provide a systematic analysis of compound disasters (Fig.3).

Fig.1 The relationship of rainfall intensity, accumulative rainfall and disaster types


Fig.2 Rainfall intensity and accumulative rainfall of Typhoon Morakot (Alishan precipitation station)


Fig.3 The locations of the disasters at  Hsiaolin Village


Fig.4 The model structure of compound disasters in Hsiaolin Village


References

  1. Chang HH (1998) Generalized computer program: Users’ manual for FLUVIAL-12: Mathematical model for erodible channels, San Diego.
  2. Chang DS, Zhang LM (2010) Simulation of the erosion process of landslide dams due to overtopping considering variations in soil erodibility along depth. Natural Hazards and Earth System Sciences 10(4): 933-946.Costa JE, Schuster RL (1988) The formation and failure of natural dams. Geological society of America bulletin 100: 1054-1068.
  3. Crosta GB, Calvetti F, Imposimato S, et al. (2001) Granular flows and numerical modelling of landslides. Report of DAMOCLES project. pp 16-36.
  4. Crosta GB, Imposimato S, Roddeman DG et al. (2006) Continuum numerical modeling of flow-like landslides, Landslide From Massive Rock Slope Failure. NATO Science Series 49(4): 211-232.
  5. Cundall PA (1971) A computer model for simulating progressive large scale movement in blocky rock systems, Proceedings of the Symposium of the International society of rock mechanics 1: II–8.
  6. Danish Hydraulic Institute (1993) MIKE 21 short description, Danish Hydraulic Institute, Hørsholm, Denmark.
  7. Egashira S, Ashida K (1992) Unified view of the mechanics of debris flow and bed-load. In: Shen HH and Satake M (eds.), Advances in Micromechanics of Granular Materials. pp 391-400.
  8. Egashira S, Miyamoto K, Itoh T (1997) Constitutive equations of debris flow and their applicability, In: Chen CL (eds.), Debris-Flow Hazards Mitigation, Water Resources Engineering Division, American Society of Civil Engineers. pp 340-349.
  9. Itoh T, Egashira S, Miyamoto K (2000) Influence of interparticle friction angle on debris-flows. In: Wieczorek GF and Naeser ND (eds.), Proceedings of the 2nd international conference on debris-flow. pp 219-228.
  10. Iverson RM (1997) The Physics of Debris Flows. Reviews of Geophysics 35: 245–296.
  11. Jia Y, Wang SS (1999) Numerical model for channel flow and morphological change studies. Journal of Hydraulic Engineering 125(9): 924–933.
  12. Miyamoto K (2002) Two dimensional numerical simulation of landslide mass movement. Journal of Erosion Control Engineering 55(2): 5-13. (In Japanese)
  13. Mizuyama T, Satofuka Y, Ogawa K et al. (2006) Estimating the outflow discharge rate from landslide dam outbursts. Disaster Mitigation of Debris flows, Slope Failures and Landslides 1:365-377.
  14. Miyamoto K (2010) Numerical simulation of landslide movement and Unzen-Mayuyama disaster in 1792, Japan, Journal of Disaster Research 5 (3), 280-287.
  15. Nakatani K, Wada T, Satofuka Y, et al. (2008) Development of “Kanako 2D (Ver.2.00),” a user-friendly one- and two-dimensional debris flow simulator equipped with a graphical user interface. International Journal of Erosion Control Engineering 1(2):62-72.
  16. Satofuka Y, Mori T, Mizuyama T, et al. (2010) Prediction of floods caused by landslide dam collapse. Journal of Disaster Research 5(3):288-295.
  17. Schuster RL, Costa JE (1986) A perspective on landslide dams, In: Schuster RL (eds.), Landslide Dams, Processes, Risk and Mitigation. pp 1-20.
  18. Shi GH, Goodman RE (1984) Discontinuous deformation analysis. In: Dowding CH , Singh MM (eds.), Proceedings of the 25th U.S. Symposium on Rock Mechanics. pp 269-277
  19. Shi GH (1993) Block system modeling by discontinuous deformation analysis. Computational Mechanics Publications, London, England. pp  209.
  20. Shieh CL, Wang CM, Chen YS et al. (2010) An overview of disasters resulted from Typhoon Morakot in Taiwan. Journal of Disaster Research 5(3): 236-244.
  21. Pudasaini SP, Wang Y, Hutter K et al. (2005) Modeling debris flows down general channels. Natural Hazards and Earth System Sciences 5: 799–819.
  22. Takahashi T (1981a) Estimation of potential debris flows and their hazardous zones. Journal of Natural Disaster Science 3 (1): 57–89.
  23. Takahashi T (1981b) Debris Flow. Annual Review of Fluid Mechanics 13: 57-77.
  24. Takahashi T, Kuang SF (1988) Hydrograph prediction of debris flow due to failure of landslide dam. Annuals of Disaster Prevention Research Institute 31 B-2:601-615. (In Japanese)
< Previous
Next >
Copyright National Cheng Kung University