IOCAS-IR  > 海洋地质与环境重点实验室
Morphology and maintenance of steep dunes near dune asymmetry transitional areas on the shallow shelf (Beibu Gulf, northwest South China Sea)
Ma, Xiaochuan1,2,3; Yan, Jun1,2,3; Song, Yongdong1; Liu, Xiansan1; Zhang, Jianxing1; Traykovski, Peter A.4
2019-06-01
Source PublicationMARINE GEOLOGY
ISSN0025-3227
Volume412Pages:37-52
Corresponding AuthorMa, Xiaochuan(mxch@qdio.ac.cn)
AbstractSymmetrical dunes can be found in areas where dune asymmetry changes sense, but in areas where dunes are not expected to be moving the development and maintenance of symmetrical dunes are poorly understood. In the southeastern Beibu Gulf, we have identified five typical dune asymmetry transitions at the depths of shallower than 50 m basing on the latest bathymetric data. Those regions are separated into two classes according to their different shapes and locations. Sand transport directions are deduced by dune migrations between surveys, simulated regional currents, and sand size trends. The two classes of the regions are found to experience opposing net sand transports from the north and south. Around the asymmetry transitions, the dunes have impressive steep sections, relatively symmetrical shapes, and almost straight crests. They have a general Height-Length (H-L) relation: H = 0.0575 L-1.0836 (R-2 = 0.834), which is steeper than dunes in other seas. Some of the dunes have extraordinary large heights exceeding a quarter of water depth, which is attributed to the preserved sand body, bidirectional sand accretion, erosion in troughs, and absence of significant erosion on crests. The steepness and straight crests of dunes adapt to the nearly symmetrical or weak asymmetrical reversing currents, which induce flow separations and reversals on both flanks of the dunes. It also suggests that dunes develop differently under sufficient and limited sand supply. Dunes will gradually grow in size when being continually supplied with sand. However, if sand supply is restricted, dunes may separate or turn into more isolated individuals to sustain the H-L relation. The H-L relation of dunes can be maintained during either growth or separation. Overall, the nearly symmetrical or weak asymmetrical reversing currents maintain the steep shapes of dunes while variations in sand supply affect their sizes. To work out the detailed transports of sediment, future observations of flow structures and related models of such two-sided steep dunes are still required.
KeywordSteep dunes Morphology Maintenance Flow separation Beibu Gulf
DOI10.1016/j.margeo.2019.03.006
Indexed BySCI
Language英语
Funding ProjectNational Natural Science Foundation of China[41876035] ; National Natural Science Foundation of China[41406061]
WOS Research AreaGeology ; Oceanography
WOS SubjectGeosciences, Multidisciplinary ; Oceanography
WOS IDWOS:000472687400004
PublisherELSEVIER SCIENCE BV
Citation statistics
Document Type期刊论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/161771
Collection海洋地质与环境重点实验室
Corresponding AuthorMa, Xiaochuan
Affiliation1.Chinese Acad Sci, CAS Key Lab Marine Geol & Environm, Inst Oceanol, Qingdao, Shandong, Peoples R China
2.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, Qingdao, Shandong, Peoples R China
3.Chinese Acad Sci, Ctr Ocean Mega Sci, Qingdao 266071, Shandong, Peoples R China
4.Woods Hole Oceanog Inst, Dept Appl Ocean Phys & Engn, Woods Hole, MA 02543 USA
First Author AffilicationInstitute of Oceanology, Chinese Academy of Sciences
Corresponding Author AffilicationInstitute of Oceanology, Chinese Academy of Sciences
Recommended Citation
GB/T 7714
Ma, Xiaochuan,Yan, Jun,Song, Yongdong,et al. Morphology and maintenance of steep dunes near dune asymmetry transitional areas on the shallow shelf (Beibu Gulf, northwest South China Sea)[J]. MARINE GEOLOGY,2019,412:37-52.
APA Ma, Xiaochuan,Yan, Jun,Song, Yongdong,Liu, Xiansan,Zhang, Jianxing,&Traykovski, Peter A..(2019).Morphology and maintenance of steep dunes near dune asymmetry transitional areas on the shallow shelf (Beibu Gulf, northwest South China Sea).MARINE GEOLOGY,412,37-52.
MLA Ma, Xiaochuan,et al."Morphology and maintenance of steep dunes near dune asymmetry transitional areas on the shallow shelf (Beibu Gulf, northwest South China Sea)".MARINE GEOLOGY 412(2019):37-52.
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