Typhoon Soudelor (2015) Induced Offshore Movement of Sand Dunes and Geomorphological Change: Fujian Coast, China

Abstract

Typhoons play a significant role in the marine sedimentary dynamic process and thus could significantly change the submarine geomorphology in their influence area. In this study, a high-resolution sub-bottom profiler and a side-scan sonar were used to detect the submarine geomorphology of the southeast coastal area of Nanri Island in the Taiwan Strait before and after Typhoon Soudelor-three times in 2015. The results show that the typhoon induced seaward movement of the sand dunes up to several tens of meters, resulting in significant changes in both the shape of the sand dunes and the scale of the exposed bedrocks. The typhoon also changed the submarine geomorphology, including the smoothing of anchor traces of fishing boats and the formation of relatively small sand dunes (groups). A comparison of the results of different surveys shows that the submarine geomorphology that was changed by Typhoon Soudelor could not recover within a short period of time. The wind field simulations of the typhoon process showed that the storm wave caused by the strong wind stress of the typhoon was a key dynamic factor for changing the submarine geomorphology.

Geomorphologic evolution of the shallow-buried abandoned Yellow River delta during the last 2000 years

“…For example, storms can have major effects on estuarine deltaic intertidal landforms, in terms of both erosion and deposition (Yang et al, 2019), and storms and wave action can lead to coastal erosion and the coarsening of beach deposits (Spencer et al, 2015;Bacino et al, 2019). Waves have become the principal driving force for shaping the topography of beaches during storms (Janssen-Stelder, 2000), leading to the landward movement of coastal dunes and significant erosion and deposition of underwater slopes (Li et al, 2019). The erosion of beaches and dunes during storms provides an important sediment source for lagoons and salt marshes (Brooks et al, 2017;Swindles et al, 2018).…”

“…Besides erosion, storm surges can also affect sediment accumulation. For example, in the case of sandbar-lagoon systems, storm surges can cause severe erosion of sandbars (Sallenger, 2000;Houser et al, 2008;Eisemann et al, 2018;Li et al, 2019), and frequent storm surges can even lead to their disintegration, sinking and disappearance (FitzGerald et al, 2008). However, storm surge waves can also transport sediment eroded from sand bars, leading to sediment accumulation by other landforms, thus forming a new sand bar-lagoon system (Koiwa et al, 2018).…”