Storm deposition layer on the Fujian coast generated by Typhoon Saola (2012)

Abstract

Typhoons have a significant effect on the marine depositional environment and depositional process. In this paper, we used the high-resolution Chirp sonar sub-bottom profiler and radioisotope detection techniques to examine the storm-deposited layer formed in the seawater near the path of Typhoon Saola along the coast of Fujian, China. The thickness of the typhoon-deposited layer acquired using these two methods was 10–25 cm. The thickness, sediment grain size, and δ13C values of the deposited sedimentary layer indicated that it was mainly matter from the re-suspension and redistribution of seafloor sediments. The particle sizes of the sediments in the storm-deposited layer became coarser, indicating that the fine-grade compositions spread over a wider range out of the coastal zone.

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

“…This strong dynamic process changes the water body (dynamic) structure and affects the suspension, transport, and distribution of sediments, thus resulting in changes in the marine sedimentation process and submarine geomorphology (i.e., movement of sand dunes and geomorphological changes). In sea areas with sufficient substance supplies (i.e., river mouths and bays), the strong dynamic process can form deposit strata caused by a typhoon event [2,4,17].…”

“…Thus, it is of great importance to investigate the effects of typhoons on submarine geomorphology, to facilitate the study of the marine sediment dynamic process under the influence of extreme events and the associated mechanisms. High-resolution modern marine geophysical detection techniques provide a new effective method to study the effect of typhoons on the modern marine sediment dynamic process [2,4]. In summary, this study used the high-resolution Chirp sonar sub-bottom profiler and side-scan sonar to determine the Typhoon Soudelor-induced offshore movement of sand dunes and submarine geomorphological changes.…”

“…Typhoons are one of the strongest air-sea interaction processes on the synoptic scale and can greatly change physical, chemical, biological, ecological, and sedimentary dynamic environments within a short period of time [1][2][3][4][5][6][7]. In an offshore area, the strong cyclonic wind stress of a typhoon can directly stir up submarine sediments, which induces transport and redistribution of the sediments, thus affecting the marine sedimentary dynamic process [2,[8][9][10][11].…”

“…Although typhoons strongly affect the marine sedimentary dynamic process and submarine geomorphology, there have been very few studies on these fields based on in situ observations so far, due to limitations in predicting typhoon paths, lack of in situ observations because of adverse weather conditions during typhoons, and also human activities (such as fishery and aquaculture) in coastal areas that strongly restrict fixed-point mooring observations [4]. In addition, the typhoon process factors, including seasonality, path, intensity, and moving speed, vary significantly from one typhoon to another, affecting the sedimentary dynamic process and submarine geomorphology.…”

“…All these limitations result in the current incomplete and imperfect system used to study the effects of typhoons on the sedimentary dynamic process and the associated submarine geomorphologic evolution. The current method mainly entails comparing the differences in the sediment properties (including sediment grain size, geochemistry, and paleomicrobes) and the submarine geomorphology before and after typhoons, to reflect the effects of typhoons on the sediment dynamic process and geomorphology, to assess their degrees of influence, and to discuss associated mechanisms by taking into account the marine dynamic environment [2,4,16,17].…”