Sediment Characteristics over Asymmetrical Tidal Sand Waves in the Dutch North Sea
Sediment Characteristics over Asymmetrical Tidal Sand Waves in the Dutch North Sea
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DOI：
10.3390/jmse8060409
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发表时间：
2020-06-01
影响因子：
2.9
通讯作者：
Borsje, Bas Wijnand
中科院分区：
文献类型：
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作者：
Cheng, Chiu Hwa;Soetaert, Karline;Borsje, Bas Wijnand
不对称底形的行为，其中包括许多潮汐沙波，是具有挑战性的理解。它们特别令人感兴趣，因为它们大多位于近海工程活动的地区。大多数关于不对称底形的实验研究考虑了河流环境，仅限于单个沙波或一些分散的沙波，并且仅关注波峰和波谷之间的差异。几乎没有任何资料是关于沉积物成分的变化沿着不对称的潮汐沙波，尽管他们丰富的近海。2017年6月和10月，研究了位于北海特克塞尔岛海岸外的非对称沙波场。共收集了102个沉积物样品，沿着一个单一的横断面，涵盖了5个完整的沙波，测量粒度组成，有机碳浓度，叶绿素a（chl-a）浓度，和沉积物渗透性。我们发现这些沉积物参数之间的沙波谷，波峰，平缓和陡峭的斜坡，包括渗透率的差异超过2倍，以及超过65 μ m的中值粒径的差异显着变化。根据这些特征，沙波可以分为两个离散的部分：缓坡+波峰和陡坡+波谷。我们的研究结果表明，一个独特的沉积物分选过程沿着特克塞尔沙波，每个沙波的两个半之间的显着差异。这些数据可作为设计近海工程项目所必需的沉积物分选过程与海底形态动力学之间联系的过程建模的输入。
The behavior of asymmetrical bedforms, which include many tidal sand waves, is challenging to understand. They are of particular interest since they are mostly located within areas prone to offshore engineering activities. Most experimental investigations regarding asymmetrical bedforms consider the riverine environment, are limited to a single sand wave or a few scattered ones, and focus only on differences between crest and trough. Hardly any information is available on sediment compositional changes along asymmetrical tidal sand waves, despite their abundance offshore. An asymmetrical sand wave field located off the coast of Texel Island in the North Sea was studied in June and October 2017. A total of 102 sediment samples were collected over two seasons along a single transect that covered five complete sand waves to measure the grain size composition, organic carbon concentration, chlorophyll-a (chl-a) concentration, and sediment permeability. We found significant variations in these sediment parameters between the sand wave trough, crest, and gentle and steep slopes, including a difference in permeability of more than 2-fold, as well as a difference in median grain size exceeding 65 mu m. Based on these characteristics, a sand wave can be divided into two discrete halves: gentle slope + crest and steep slope + trough. Our results indicate a distinct sediment-sorting process along the Texel sand waves, with a significant difference between the two halves of each sand wave. These data could serve as input for process-based modeling of the link between sediment-sorting processes and seabed morphodynamics, necessary to design offshore engineering projects.