Abstract
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.
Highlights
The 2004 Indian Ocean tsunami and the 2011 Tohoku earthquake and tsunami caused large-scale geomorphologic changes in coastal areas during the erosional phases of inflow and outflow (Pari et al, 2008; Goto et al, 2011a; Tanaka et al, 2011; Haraguchi et al, 2012; Hirao et al, 2012; Udo et al, 2013; Imai et al, 2015)
Masaya et al.: Investigating beach erosion related with tsunami sediment transport vironment and coastal environments are primed for natural processes to resume and redistribute sediments onshore to restore the coastal environment to similar pre-tsunami configurations
Because of insufficient knowledge about the topographic recovery process after a tsunami, this study used sediment transport modeling to identify the erosional and depositional processes affecting the coastal zone at Phra Thong Island, Thailand, during the 2004 Indian Ocean tsunami
Summary
The 2004 Indian Ocean tsunami and the 2011 Tohoku earthquake and tsunami caused large-scale geomorphologic changes in coastal areas during the erosional phases of inflow and outflow (Pari et al, 2008; Goto et al, 2011a; Tanaka et al, 2011; Haraguchi et al, 2012; Hirao et al, 2012; Udo et al, 2013; Imai et al, 2015). The erosional phases translocated sediments onshore and offshore and primed the coastal zone for rapid (months to decades) recovery (Choowong et al, 2009; Ali and Narayama, 2015; Udo et al, 2016; Saegusa et al, 2017; Koiwa et al, 2018). Masaya et al.: Investigating beach erosion related with tsunami sediment transport vironment and coastal environments are primed for natural processes to resume and redistribute sediments onshore to restore the coastal environment to similar pre-tsunami configurations
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