Advertisement

Natural Hazards

, Volume 63, Issue 2, pp 939–963 | Cite as

Determination of mangrove forest performance in reducing tsunami run-up using physical models

  • H. Ismail
  • A. K. Abd Wahab
  • N. E. Alias
Original Paper

Abstract

Coastal ecosystems such as mangroves fringing tropical coastlines have been recognized as natural protectors of the coastal areas against destructive attack of a tsunami. In this paper, the authors aim to investigate the interaction of a tsunami wave on a typical mangrove forest and to determine its performance in reducing the run-up. A laboratory experiment using a hydraulic flume with a mangrove forest model was carried out in which tests were conducted by varying the vegetation widths of 0, 1, 2 and 3 m and average densities of 8, 6 and 4 trees per 100 cm2 using a scale ratio of 1:100. Two conditions of water levels were considered in the experiments at several tsunami wave heights between 2.4 and 14 cm. The dam break method used in the experiments produced two types of waves. At low water condition, a bore was developed and subsequently, a solitary wave was produced during high water. The results of the experiments showed that in general, vegetation widths and densities demonstrate a dampening effect on tsunami run-up. A larger vegetation width was found to be more effective in dissipating the wave energy. The first 1 m width of mangrove forest could reduce 23–32 % during high water and 31–36 % during low water. Increasing the mangrove forest width to 2 and 3 m could further increase the average percentage of run-up reduction by 39–50 % during high water and 34–41 % during low water condition. It was also observed that densities of the mangrove forest do not influence the run-up reduction as significantly as the forest widths. For mangrove forest densities to be significantly enough to reduce more tsunami run-up, an additional density of 4 trees/100 m2 needs to be provided. The experiments also showed that mangrove roots are more effective in reducing the run-up compared to the trunks and canopies. The experiments managed to compare and present the usefulness of mangrove forests in dissipating wave energy and results produced are beneficial for initiating design guidelines in determining setback limits or buffer zones for development projects in mangrove areas.

Keywords

Tsunamis Mangroves Vegetation cover Run-up Physical models Dam break 

Notes

Acknowledgments

The authors wish to extend their appreciation to the Ministry of Higher Education (MOHE) Malaysia for funding the research through the Fundamental Research Grant Scheme (FRGS), vote 78122. We are also indebted to the distinguished reviewers for their constructive comments and advice.

References

  1. Abd Wahab AK, Ismail H, Alias NE (2011) An investigation on tsunami wave energy dissipation over vegetated coasts. Final Report Project 78122. Universiti Teknologi MalaysiaGoogle Scholar
  2. Alias NE (2010) Tsunami run-up on vegetated coastal slopes. M.Eng Thesis, Universiti Teknologi MalaysiaGoogle Scholar
  3. Arnason H (2005) Interactions between an incident bore and a free-standing coastal structure. University of Washington, WashingtonGoogle Scholar
  4. Burger B (2005) Wave Attenuation in mangrove forests. M.Sc. Thesis, Delft University of TechnologyGoogle Scholar
  5. Chanson H (2005) Applications of the saint-venant equations and method of characteristics to the dam break wave problem (no. CH 55/05). The University of Queensland, Brisbane, AustraliaGoogle Scholar
  6. Chanson H, Aoki S, Maruyama M (2003) An experimental study of tsunami run-up on dry and wet horizontal coastlines. Sci Tsunami Hazards 20(5):278–293Google Scholar
  7. Cintron G, Novelli YS (1984) Methods for studying mangrove structure. In: Snedaker SC, Snedaker JG (eds) The mangrove ecosystem: research methods. UNESCO, Paris, pp 91–113Google Scholar
  8. Fogarty D (2005) Tsunami-hit nations look to save mangroves. Reuters, 17 January 2005 Google Scholar
  9. Gedik N, Irtem E, Kabdasli S (2005) Laboratory investigation on tsunami run-up. Ocean Eng 32:513–528CrossRefGoogle Scholar
  10. Harada K, Imamura F (2002). Experimental study on the effect in reducing tsunami by the coastal permeable structures. Paper presented at the Proceedings of the Twelfth (2002) International Offshore and Polar Engineering Conference, Kitakyushu, JapanGoogle Scholar
  11. Harada K, Kawata Y (2005) Study on tsunami reduction effect of coastal forest due to forest growth. Annu Disast Prevent Res Instit Kyoto Uni No. 48C:161–165Google Scholar
  12. Hiraishi T (2000) Characteristics of Aitape tsunami in 1998 Papua New Guinea (no. 4): Report of Port and Harbour Research Institute, JapanGoogle Scholar
  13. Hiraishi T, Harada K (2003) Greenbelt tsunami prevention in south-pacific region (no. vol. 42, no. 2): Report of Port and Airport Research InstituteGoogle Scholar
  14. Imai K, Matsutomi H (2005) Fluid force on vegetation due to tsunami flow on sand spit. In: Satake K (ed) Tsunamis: case studies and recent development. Springer, The Netherlands, pp 293–304Google Scholar
  15. IOC (2008) Tsunami glossary, Intergovernmental Oceanographic Commission. UNESCO IOC Technical Series, 85. Paris (English) Google Scholar
  16. Irtem E, Gedik N, Kabdasli MS, Yasa NE (2009) Coastal forest effects on tsunami run-up heights. Ocean Eng 36:313–320CrossRefGoogle Scholar
  17. Kathiresan K, Rajendran N (2005) Coastal mangrove forests mitigated tsunami. Estuar Coast Shelf Sci 65(3):601–606CrossRefGoogle Scholar
  18. Li Y (2000) Tsunamis: non-breaking and breaking solitary wave run-up. PhD Thesis, California Institute of Technology, Pasadena, CaliforniaGoogle Scholar
  19. Mascarenhas A, Jayakumar S (2008) An environmental perspective of the post-tsunami scenario along the coast of Tamil Nadu, India: Role of sand dunes and forests. J Environ Manag 89(1):24–34CrossRefGoogle Scholar
  20. Mazda Y, Wolanski E, Ridd PV (2007) The role of physical processes in mangrove environments. TERRAPUB, TokyoGoogle Scholar
  21. Moberg F, Ronnback P (2003) Ecosystem services of the tropical seascape: interactions, substitutions and restoration. Ocean and Coastal Management 46. Elsevier, Amsterdam, pp 27–46Google Scholar
  22. Onrizal KC, Mansor M (2009) The effect of tsunami in 2004 on mangrove forests, Nias Island, Indonesia. Wetl Sci 7(2):130–134Google Scholar
  23. Ramsden JD (1993) Tsunamis: forces on a vertical wall caused by long waves, bores, and surges on a dry bed. Report No KH-R-54, California Institute of Technology, Pasadena, California, USAGoogle Scholar
  24. Sorensen RM (2006) Basic coastal engineering (3rd edn). New York: Springer Science+Business Media, Inc.Google Scholar
  25. Synolakis CE (1986) The run-up of long waves. Doctor of Philosophy Thesis, California Institute of Technology, CaliforniaGoogle Scholar
  26. Thusyanthan NI, Madabhushi SPG (2008) Tsunami wave loading on coastal houses: a model approach. In: Proceedings of the Institution of Civil Engineers—Civil Engineering 161(2):77–86Google Scholar
  27. Valentin H, Jens U, Willi, H (2005) Tsunami run-up—a hydraulic perspective. J Hydraulic Eng 131(9):743–747 Google Scholar
  28. Wang ZY, Larsen P, Nestmann F, Dittrich A (1998) Resistance and drag reduction of flows of clay suspension. J Hydraul Eng 124(1):41–49Google Scholar
  29. Yanagisawa H, Koshimura S, Goto K, Miyagi T, Imamura F, Ruangrassamee A et al (2009) The reduction effects of mangrove forest on a tsunami based on field surveys at Pakarang Cape, Thailand and numerical analysis. Estuar Coast Shelf Sci 81(1):27–37CrossRefGoogle Scholar
  30. Yeh HH (1991) Tsunami bore run-up. In: Natural Hazards (vol 4). Kluwer Academic Publisher, Dordrecht, The NetherlandsGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  1. 1.Coastal and Offshore Engineering InstituteUniversiti Teknologi Malaysia International CampusKuala LumpurMalaysia
  2. 2.Faculty of Civil EngineeringUniversiti Teknologi MalaysiaSkudai, Johor BahruMalaysia

Personalised recommendations