Abstract. The 2004 Indian Ocean tsunami and the 2011 Tōhoku earthquake and
tsunami caused large-scale topographic changes in coastal areas. Whereas
much research has focused on coastlines that have or had large human
populations, little focus has been paid to coastlines that have little or no
infrastructure. The importance of examining erosional and depositional
mechanisms of tsunami events lies in the rapid reorganization that
coastlines must undertake immediately after an event. A thorough
understanding of the pre-event conditions is paramount to understanding the
natural reconstruction of the coastal environment. This study examines the
location of sediment erosion and deposition during the 2004 Indian Ocean
tsunami event on the relatively pristine Phra Thong Island, Thailand.
Coupled with satellite imagery, we use numerical simulations and sediment
transportation models to determine the locations of significant erosion and
the areas where much of that sediment was redeposited during the tsunami
inundation and backwash processes. Our modeling approach suggests that
beaches located in two regions on Phra Thong Island were significantly
eroded by the 2004 tsunami, predominantly during the backwash phase of the
first and largest wave to strike the island. Although 2004 tsunami deposits
are found on the island, we demonstrate that most of the sediment was
deposited in the shallow coastal area, facilitating quick recovery of the
beach when normal coastal processes resumed.