Shawn Sim is a PhD candidate at the Asian School of the Environment (ASE) – NTU. He received his Bachelor’s degree in Environmental Engineering from NTU. In August 2010, he enrolled in the PhD program at ASE under the supervision of Associate Professor Huang Zhenhua. During his PhD, he has focused on using physical and numerical models to study the onshore flow of tsunami that includes both hydrodynamic and sediment transport phenomenon.
Chair of the Oral defense
- Associate Professor Charles Martin Rubin (Chair), Asian School of the Environment, Singapore
Members of the Examination Committee:
- Assistant Professor Benoit Taisne (Internal Examiner), Earth Observatory of Singapore and Asian School of the Environment, Singapore
- Associate Professor Edmond Lo Yat-Man (External Examiner), School of Civil and Environmental Engineering, Nanyang Technological University, Singapore
- Professor Chiew Yee Meng , School of Civil and Environmental Engineering, Nanyang Technological University, Singapore
- Associate Professor Huang Zhenhua, Department of Ocean and Resources Engineering, University of Hawaii at Manoa, USA
The focus of the thesis is on onshore tsunami flows with special attention on tsunami run-up. In the aftermath of a tsunami, the most evident clue on the extent of a run-up is the water marks left behind. The trim-line recorded by surveyors is one of the most valuable pieces of information needed to determine the hydrodynamics parameters of the tsunami. However, it is also known that the most commonly used 2-D hydrodynamic models that attempt to reproduce the tsunami event do not produce good results during the onshore propagation phase. To bridge this gap, the use of an amplification factor proposed by Satake (1994) is investigated in this study. Experimentally, we used solitary waves to impinge on a model scaled coastal cliff to examine the flow depth at different onshore locations. The measured data are compared with the numerical results using the Delft3D-FLOW model. We also used dam break waves to evaluate the run-up both experimentally and numerically. The reason for doing so was two-fold. First, dam break waves can provide us with a comparison to the often used solitary waves. Second, due to the discovery of a cave that has well preserved tsunami deposits off the coast of Banda Aceh, Indonesia, we found that experimental dam break waves have the potential not only to bring the sediments in, but also allow ample time for deposition to occur. Numerically, the sedimentation time within the cave is not easy to obtain using 2-D numerical models. Hence, based on the trim-line time series recorded, we provided a hypothetical sedimentation time that can be obtained using non-sediment laden flow tests.