Abstract
Devastating tsunami waves can mobilize substantial amount of coastal sediment. Scouring is the primary damage caused by tsunamis. Offshore submerged or emerged breakwaters are coastal structures that are commonly employed to provide protection to valuable coastal beaches from energetic ocean waves. However, the protection capabilities of tsunami scour by submerged or emerged breakwater are less understood compared to tsunami runup and tsunami inundation. A set of laboratory experiments are reported in this study on protection of tsunami-induced scour by submerged or emerged breakwaters on a sandy beach. FLOW-3D is used in this paper to calculate flow field of tsunami wave propagation over the breakwater in order to help us to understand the sediment transport and tsunami scour process. Our experiments show that the submerged breakwater could not effectively reduce the tsunami scouring and only could affect the height and position of deposition sand bar. The emerged breakwater could significantly effectively reduce the tsunami scouring on the sandy beach; meanwhile, local scouring caused by plunging jet occurs mainly on the both sides of the structure. It is also found that for typical tsunamis, the scour depth at shoreward is unlikely to reach its equilibrium stage. Local scouring damage is one of the main factors leading to the destruction of coastal structures during a tsunami event. The most important governing parameters on local scouring around breakwater were defined. The final empirical relations that define the magnitude and position of local scouring around the breakwater were presented. The information reported in this study is useful for local authorities to assess potential tsunami damage of structure and to have a better plan for tsunami preventing and reducing.
Similar content being viewed by others
References
Alsina JM, Falchetti S, Baldock TE (2009) Measurements and modelling of the advection of suspended sediment in the swash zone by solitary waves. Coast Eng 56(5–6):621–631
Ca V, Yamamoto Y, Charusrojthanadech N (2000) Improvement of prediction methods of coastal scour and erosion due to Tsunami back-flow. In: Proceedings of the twentieth international offshore and polar engineering conference, Beijing, PR China, pp 1053–1062
Chen J, Huang ZH, Jiang CB, Deng B, Long YN (2012) An experimental study of changes of beach profile and mean grain size caused by tsunami-like waves. J Coast Res 28(5):1303–1312
Chen J, Huang ZH, Jiang CB, Deng B, Long YN (2013) Tsunami-induced scour at coastal roadways: a laboratory study. Nat Hazards 69:655–674
Dean RG, Dalrymple RA (2001) Coastal Processes with Engineering Applications. Cambridge University Press, Cambridge
Flow Science Inc (2009) FLOW-3D user manual version 9.4. Flow Science Inc, Santa Fe, New Mexico, USA
Goring DG (1979) Tsunamis-the propagation of long waves on to a shelf. California Institute of Technology, Pasadena
Jiang CB, Chen J, Yao Y, Liu J, Deng Y (2015) Study on threshold motion of sediment and bedload transport by tsunami waves. Ocean Eng 100:97–106
Kato F, Sato S, Yeh H (2000) Large-scale experiment on dynamic response of sand bed around a cylinder due to tsunami. In: Proceedings of 27th international conference on coastal engineering, ASCE, Sydney, Australia, pp. 1848–1859
Kobayashi N, Lawrence A (2004) Cross-shore sediment transport under breaking solitary waves. J Geophys Res 109:C030047
Li L, Huang Z, Qui Q, Natawidjaja DH, Sieh K (2012) Tsunami-induced coastal change: scenario studies for Painan, West Sumatra, Indonesia. Earth Planets Space 64:799–816
Madsen PA, Fuhrman DR, Schaeffer HA (2008) On the solitary wave paradigm for tsunamis. J Geophys Res. doi:10.1029/2008jc004932
Nakamura T, Kuramitsu Y, Mizutani N (2008) Tsunami scour around a square structure. Coast Eng J 50(2):209–246
Nakamura T, Mizutani N, Yim SC (2009) A three-dimensional coupled fluid-sediment interaction model with bed-load/suspended-load transport for scour analysis around a fixed structure. J Offshore Mech Arctic Eng ASME 131(3):031104-1–031104-9
Seiji WN, Uda T, Tanaka S (1987) Statistical study on the effect and stability of detached breakwaters. Coast Eng Jpn 30(1):121–131
Sumer BM, Sen MB, Karagali I, Ceren B, Fredse J, Sottile M, Zilioli L, Fuhrman DR (2011) Flow and sediment transport induced by a plunging solitary wave. J Geophys Res 116:C01008
Synolakis CE, Bernard EN (2006) Tsunami science before and beyond Boxing Day 2004. Philos Trans A Math Phys Eng Sci 364(1845):2231–2265
Tonkin S, Yeh H, Kato F, Sato S (2003) Tsunami scour around a cylinder. J Fluid Mech 496:165–192
Tsujimoto G, Yamada F, Kakinoki T (2008) Time-space variation and spectral evolution of sandy beach profiles under tsunami and regular waves. In: Proceedings of the International Offshore and Polar Engineering Conference, Vancouver, BC, Canada, ISOPE, July 6–11, pp. 523–527
Young YL, Xiao H, Maddux TB (2010) Hyro- and morpho-dynamic modeling of breaking solitary waves over sand beach. Part I: experimental study. Mar Geol 269:107–118
Acknowledgments
The study is financially supported by the National Natural Science Foundation of China (Nos. 51239001 and 51409022) and the Scientific Research Fund of Hunan Provincial Education Department (Nos. 13B130 and YB2015B034). Partial support also comes from the Program for Ministry of Communications Key Laboratory of Port, Waterway and Sedimentation Engineering and the Graduate Student Research Innovation Project of Hunan Province (No. CX2015B360).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Chen, J., Jiang, C., Yang, W. et al. Laboratory study on protection of tsunami-induced scour by offshore breakwaters. Nat Hazards 81, 1229–1247 (2016). https://doi.org/10.1007/s11069-015-2131-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11069-015-2131-x