Articles | Volume 17, issue 5
https://doi.org/10.5194/nhess-17-641-2017
https://doi.org/10.5194/nhess-17-641-2017
Research article
 | 
10 May 2017
Research article |  | 10 May 2017

A numerical study of tsunami wave impact and run-up on coastal cliffs using a CIP-based model

Xizeng Zhao, Yong Chen, Zhenhua Huang, Zijun Hu, and Yangyang Gao

Abstract. There is a general lack of understanding of tsunami wave interaction with complex geographies, especially the process of inundation. Numerical simulations are performed to understand the effects of several factors on tsunami wave impact and run-up in the presence of gentle submarine slopes and coastal cliffs, using an in-house code, a constrained interpolation profile (CIP)-based model. The model employs a high-order finite difference method, the CIP method, as the flow solver; utilizes a VOF-type method, the tangent of hyperbola for interface capturing/slope weighting (THINC/SW) scheme, to capture the free surface; and treats the solid boundary by an immersed boundary method. A series of incident waves are arranged to interact with varying coastal geographies. Numerical results are compared with experimental data and good agreement is obtained. The influences of gentle submarine slope, coastal cliff and incident wave height are discussed. It is found that the tsunami amplification factor varying with incident wave is affected by gradient of cliff slope, and the critical value is about 45°. The run-up on a toe-erosion cliff is smaller than that on a normal cliff. The run-up is also related to the length of a gentle submarine slope with a critical value of about 2.292 m in the present model for most cases. The impact pressure on the cliff is extremely large and concentrated, and the backflow effect is non-negligible. Results of our work are highly precise and helpful in inverting tsunami source and forecasting disaster.

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Short summary
Numerical simulations are performed to understand the effects of several factors on tsunami wave impact and run-up in the presence of submarine gentle slopes and coastal cliffs using an in-house code. The run-up on a toe-erosion cliff is smaller than that on a normal cliff. Two impact pressure peaks exist during the tsunami wave run-up and impact. One is the direct impact pressure when tsunami waves first hit the coastal cliff, and the other is caused by the backflow from the cliff run-up.
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