35. A STUDY FOR THE SEDIMENT TRANSPORT BY THE 2004 INDIAN OCEAN TSUNAMI ALONG THE NATURAL COAST OF HAMBANTOTA, SRI-LANKA

Abstract

In this study, we investigated the sediment transport due to the 2004 Indian Ocean tsunami along the natural coast at Hambantota, Sri-lanka. Bathymetry and topography surveys before and after the tsunami were conducted and results showed significant erosion by the tsunami, especially around the places where shoreline discontinuations were observed. We conducted a numerical simulation of tsunami propagation as well as the bathymetry change induced by the tsunami. Furthermore, we also estimated the bathymetry change due to the usual sea waves at the coast. Our numerical results suggested that the tsunami has strong bottom shear stress at specific landform such as a river mouth and a cape. We also found that the sediment erosion and accretion due to the tsunami had been mitigated by usual waves after the tsunami. th /Dec/2004 Indian Ocean tsunami, we conducted the bathymetry survey and compared the depth before and after the tsunami to grasp the geological change induced by the tsunami. Moreover, we executed the additional survey about 3 years after the tsunami in order to comprehend the influence of the coastal process by the usual ocean waves. In this study, we also apply numerical simulation to the event and use the survey data as the evidence by inspection. In the numerical analysis, we reproduce not only the propagation of the tsunami and topography change by the tsunami but also the bathymetry change caused by the usual ocean waves after the tsunami. The purpose of the study is to consider sediment transport mechanism along the natural coast by the tsunami and the influence of the sea waves after the tsunami.