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Tide‐induced bedload transport pathways in a multiple‐sand‐ridge system offshore of Hainan Island in the Beibu Gulf, northwest South China Sea
Author(s) -
Ma Xiaochuan,
Li Jinyuan,
Yan Jun
Publication year - 2018
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.4428
Subject(s) - bed load , geology , ridge , sediment transport , submarine pipeline , bedform , geomorphology , crest , oceanography , sediment , paleontology , physics , quantum mechanics
Modern sand transport pathways in a multiple‐sand‐ridge system are elusive and have rarely been studied in recent years. We report herein a field with four en echelon linear sand ridges offshore of Hainan Island in the Beibu Gulf and describe the distribution and morphology of these sand ridges in detail for the first time. Dune crest comparisons and seismic profiles are also interpreted to assess sand transport over the dunes. Based on a Delft 3D model, regional tidal currents and tide‐induced bedload transport in the multiple‐sand‐ridge system were simulated to provide insights into the related bedload transport paths. The results show that bedload transport and residual flows are mostly directed to the south on the east side of the sand ridges and to the north on the west side, and these differences coincide with dune asymmetries and migrations. Cross‐ridge transport is weak and mostly converges on the crests of sand ridges from the two flanks. The bedload transport is unbalanced on either flank of the sand ridges, thus leading to the asymmetry and crest kinks of the sand ridges. A distinct correlation is not observed between the net cross‐ridge sand transport and sand ridge asymmetry. In this system, cross‐swale transport is significant between the neighboring sand ridges and helps construct the bedload transport circulation in the swales. Sand accretion also occurs in the swales and benefits from the southwestward bedload transport from the north end of sand ridge 3. Distinct evidence has not been found for closed bedload transport circulation around sand ridges in this multiple‐sand‐ridge system, although limited clockwise current vortices develop on several sand ridges. Additional field observations and simulations are required to characterize the suspended load transport in a multiple‐sand‐ridge system, and the effects of local sand supply conditions on sand transport also need further evaluation. Copyright © 2018 John Wiley & Sons, Ltd.