Response of bedload transport, submarine topography, and dune internal structures to typhoon processes off Dongfang coast in the Beibu Gulf

• Published in: Acta Oceanologica Sinica
• Main Authors: Ma Xiaochuan, Yan Jun, Fan Fengxin, Yao Ping, Ma, XC
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: Typhoon; Bedload Transport; Sand Dune; Internal Structure; Beibu Gulf; Oceanography; Science & Technology; Physical Sciences; CANADIAN-BEAUFORT SEA; SEDIMENT-TRANSPORT; ATLANTIC BIGHT; NORTH-CAROLINA; COMBINED FLOWS; BED ROUGHNESS; INNER SHELF; STORM; SHOREFACE; CURRENTS; Beaufort Sea
• Online Access: http://ir.qdio.ac.cn/handle/337002/16315; https://doi.org/10.1007/s13131-013-0296-2

Bedload sediment transport was estimated by the SEDTRANS96 model based on three-day hydrodynamics data obtained off the Dongfang coast in the Beibu Gulf during Typhoon Ketsana in September 2009. Bed-forms on the sea floor off the Dongfang coast and internal structures of a typical dune were interpreted to evaluate storm influences on individual dunes and the dune field. Results indicated that flow forcings and related bedload transport were both strengthened significantly due to Typhoon Ketsana. The measurements and modeling results, which mainly included three different stages, presented noticeable phasic variation. The three stages were dominated by tidal current (Period I), tidal current combined with wind-induced waves (Period II), and swells combined with tidal current and seaward flows (Period III). This phasic variation could be a common trait of hydrodynamics due to typhoons moving westwardly to the south of Hainan Island and Beibu Gulf in South China Sea. Results indicated that the maximum bedload transport rate for every burst in Period III was almost 100 times larger than that in Period I and was ten times larger than that in Period II. However, the short-term increase in bedload transport induced by storms like Ketsana did not change the long-term evolution of dune morphology. Evidence was given by the internal structures of a typical dune, which revealed renewed modification under subsequent moderate conditions after storm erosion. Instead, storms may influence at different scales and regional allocation of sand dunes in some large areas because changes of the sea floor in large scales can hardly be recovered. More surveys during and after storm passage are also needed to document the level of positive contribution to forward migration. Bedload sediment transport was estimated by the SEDTRANS96 model based on three-day hydrodynamics data obtained off the Dongfang coast in the Beibu Gulf during Typhoon Ketsana in September 2009. Bed-forms on the sea floor off the Dongfang coast and internal ...