MODELLING NEARSHORE WAVES AND OVERTOPPING USING A STOCHASTIC TYPHOON SET
ICCE 2014 Cover Image
PDF

Keywords

Overtopping
Waves
Typhoons
Inundation

How to Cite

Maskell, J. H., Grieser, J., Rodney, J., Zhao, Q., Bruneau, N., Mueller, K., & Astorquia, A. (2014). MODELLING NEARSHORE WAVES AND OVERTOPPING USING A STOCHASTIC TYPHOON SET. Coastal Engineering Proceedings, 1(34), posters.38. https://doi.org/10.9753/icce.v34.posters.38

Abstract

Typhoons and the storm surges and large waves generated by them have caused severe coastal damage in Japan such as during typhoon Vera in 1959. This event struck the Ise Bay region of Japan and caused wide spread devastation where coastal sea walls were destroyed and storm surges caused significant flooding destroying thousands of buildings and contaminating drinking water. This event caused approximately $1.9 billion worth of damage in today's money (RMS report). Whilst Japan is well defended against surge and waves caused by typhoons some areas of defence could be liable to overtopping by very large waves acting on increased sea level due to surge and wave-setup. Breaching by powerful wave action may also occur exacerbating the situation and leaving low lying land susceptible to flooding. For example, during typhoon Vera earthen levees were either overtopped or breached and only defences constructed since 1953 along one side of Ise Bay after a previous typhoon could withstand the increased water levels and force of the waves (JWF, 2005). In this respect defences are constructed to design levels based on previous experience including a small tolerance level and may not cope with a storm that occurs in the tail end of the severity distribution. Were the 1959 Vera event to occur today, damage due to waves and storm surge could add up to $6 billion to total value of loss to residential properties including the wind loss despite improved flood defences (RMS report). It is important to try and quantify the possibility of flooding by all probable typhoons now and in the future. To estimate the potential loss due to certain events stochastic sets of typhoons can be statistically generated to create thousands of scenarios to drive surge and wave models and predict the magnitude of the surge and wave height at the coast (e.g. Yasuda et al., 2011). Modelling waves is very computationally expensive. Therefore, to create an event set based on thousands of typhoons a simplification of the modeling approach for waves at the coastal defences is required before simulating any subsequent overtopping. In this work a modeling system is developed to propagate the most severe typhoons (in terms of wave generation) in a stochastic set through a wave model to calculate any subsequent overtopping that is computationally viable and has a high degree of flexibility to explore uncertainties and investigate a range of scenarios.
https://doi.org/10.9753/icce.v34.posters.38
PDF

References

EurOtop Wave Overtopping of Sea Defences and Related Structures: Assessment Manual (Overtopping Course Edition, November 2012). Retrieved from http://www.overtopping-manual.com/

Goda, Y., 2008. Wave setup and longshore currents induced by directional spectral waves:

Prediction formulas based on numerical computation results. Coastal Engineering Journal, 50(4),

pp. 397-440.

JWF (Japan Water Forum), 2005. Typhoon Isewan (Vera) and its Lessons. Tokyo: Japan Water Forum. Retrieved from http://www.waterforum.jp/jpn/katrina/Typhoon_Isewan.pdf

Komen, G.J., Cavaleri, L., Doneland, M., Hasselmann, K., Hasselmann S. and Janssen, P.A.E.M. (1994). Dynamics and modelling of ocean waves. Cambrigde University Press, UK, 560pp.

Konishi, T., 1997: A cause of storm surges generated at the ports facing open oceans - effect of

wave setup -, Umi to Sora (Sea and Sky), 73, 35-44.

RMS Special Report, 2009. 1959 Super Typhoon Vera: 50-Year Retrospective. Retrieved from https://support.rms.com/publications/1959_Typhoon_Vera.pdf

Yasuda, T., Mase, H., Kunitomi, S., Mori, N., & Hayashi, Y. (2011). STOCHASTIC TYPHOON MODEL AND ITS APPLICATION TO FUTURE TYPHOON PROJECTION. Coastal Engineering Proceedings, 1(32), management.16. doi:10.9753/icce.v32.management.16

Authors retain copyright and grant the Proceedings right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this Proceedings.