Sediment transport processes under tsunami waves – a case study of tsunami deposits in a coastal cave in Aceh, Sumatra
The final goal of the on-going three-year project is to develop a process-based, coupled hydrodynamic and morphological model for simulating sediment transport and deposit under tsunami waves. This validated model will then be used to investigate and interpret the characteristics of sediment deposits in the coastal cave near Aceh, Sumatra, which was discovered after the 2004 Sumatra Earthquake and Tsunamis. During the second year of the project, we have completed the design and installation of a novel tsunami generation system in the Hydraulics Engineering Laboratory at NUS. The new system combines two types of wave generation mechanisms: a piston-type wavemaker and a dam-break device. This set-up can generate larger and longer bore-like leading tsunami waves in the laboratory scale. Preliminary experiments have been conducted to test two components separately. Wave gages were used to record the free surface elevations at different locations. An advanced imaging system (Bubble Image Velocimetry, BIV) was also employed to capture the wave profile and velocity of bubbly flows. To facilitate the physical experimental design, advanced CFD models are developed to optimize the efficiency of wave generation.
During 2018 we have conducted a field survey to obtain the high-resolution (5cm) geometry inside the coastal cave in Banda Aceh. The cave model was then meshed and a numerical model was used to simulate the inundation process that the cave underwent during the 2004 Indian Ocean Tsunami. Finally, the laboratory set up at the hydraulics lab in NUS continued to be upgraded, and the new Particle Image Velocimetry (PIV) system was applied to measure velocities under undulating bores. The field survey on the cave was conducted in collaboration with the team from Syiah Kuala University led by Professor Nazli Ismail.
- Earth Observatory of Singapore
Ignacio Barranco, Dong Wang, Yun-Ta Wu, Pablo Higuera, Civil and Environmental Engineering, National University of Singapore
Nazli Ismail, Syiah Kuala University