| Response of bedload transport, submarine topography, and dune internal structures to typhoon processes off Dongfang coast in the Beibu Gulf |
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| 作者姓名： | MA Xiaochuan YAN Jun FAN Fengxin YAO Ping |
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| 作者单位： | Key Laboratory ofMarine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;University of Chinese Academy of Sciences, Beijing 100049, China;Key Laboratory ofMarine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;Key Laboratory ofMarine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;Zhanjiang Branch of China National Offshore Oil Corporation, Zhanjiang 524057, China |
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| 基金项目： | A CAS (Chinese Academy of Sciences) and CNOOC (China National Offshore Oil Corporation) collaborative research project. |
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| 摘 要： | 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. Bedforms 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.
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| 关 键 词： | typhoon bedload transport sand dune internal structure Beibu Gulf |
| 收稿时间： | 2011/11/24 0:00:00 |
| 修稿时间： | 6/4/2012 12:00:00 AM |
Response of bedload transport, submarine topography, and dune internal structures to typhoon processes off Dongfang coast in the Beibu Gulf |
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| MA Xiaochuan,YAN Jun,FAN Fengxin,YAO Ping.Response of bedload transport, submarine topography, and dune internal structures to typhoon processes off Dongfang coast in the Beibu Gulf[J].Acta Oceanologica Sinica,2013,32(4):27-40. |
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| Authors: | MA Xiaochuan YAN Jun FAN Fengxin and YAO Ping |
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| Institution: | 1.Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;University of Chinese Academy of Sciences, Beijing 100049, China2.Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China3.Zhanjiang Branch of China National Offshore Oil Corporation, Zhanjiang 524057, China |
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| Abstract: | 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. Bedforms on the sea floor off the Dongfang coast and internal structures of a typical dune were interpreted to evaluate storminfluences on individual dunes and the dune field. Results indicated that flow forcings and related bedload transportwere both strengthened significantly due to Typhoon Ketsana. Themeasurements 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 typhoonsmoving 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-termincrease in bedload transport induced by storms like Ketsana did not change the long-termevolution of dunemorphology. Evidence was given by the internal structures of a typical dune,which revealed renewedmodification under subsequentmoderate conditions after stormerosion. 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 stormpassage are also needed to document the level of positive contribution to forwardmigration. |
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| Keywords: | typhoon|bedload transport|sand dune|internal structure|Beibu Gulf |
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