Morphological and sedimentological response of a mixed-energy barrier island tidal inlet to storm and fair-weather conditions
Morphological and sedimentological response of a mixed-energy barrier island tidal inlet to storm and fair-weather conditions
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DOI：
10.5194/esurf-2-363-2014
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发表时间：
2013-11
期刊：
影响因子：
3.9
通讯作者：
G. Herrling;C. Winter
中科院分区：
文献类型：
--
作者：
G. Herrling;C. Winter
抽象的。障壁岛系统之间的落潮三角洲环境的特点是由一个复杂的形态与落潮和洪水为主的通道，浅滩和冲砂坝连接落潮三角洲平台到相邻的岛屿。这些形态特征揭示了特有的表层沉积物粒度分布，并不断适应主要的水动力。混合能源潮汐入口Otzumer Balje之间的东弗里斯兰屏障岛的朗格奥格和Spiekeroog在北海南部已被选为模型研究区的形态学和沉积学的相关水动力驱动程序的识别。我们比较了高能量，波浪为主的风暴条件，中期，潮汐为主的天气条件下潮汐入口形态和沉积学与过程为基础的数值模型的效果。一个多部分的方法，在150和450 μm之间的五个粒度级允许模拟相应的表面沉积物粒度分布。确定不同条件下的净沉积物通量：在风暴条件下，推移质泥沙输运一般是岸上的浅落潮三角洲浅滩，而细粒悬浮泥沙绕过潮汐入口波驱动电流。晴天时，泥沙输移主要集中在进口喉道和边缘泄洪道。我们如何观察到的沉积物粒度分布和形态的反应，在混合能源潮汐入口的结果是波为主的不太频繁的风暴条件和中期，潮汐占主导地位的好天气条件。
Abstract. The environment of ebb-tidal deltas between barrier island systems is characterized by a complex morphology with ebb- and flood-dominated channels, shoals and swash bars connecting the ebb-tidal delta platform to the adjacent island. These morphological features reveal characteristic surface sediment grain-size distributions and are subject to a continuous adaptation to the prevailing hydrodynamic forces. The mixed-energy tidal inlet Otzumer Balje between the East Frisian barrier islands of Langeoog and Spiekeroog in the southern North Sea has been chosen here as a model study area for the identification of relevant hydrodynamic drivers of morphology and sedimentology. We compare the effect of high-energy, wave-dominated storm conditions to mid-term, tide-dominated fair-weather conditions on tidal inlet morphology and sedimentology with a process-based numerical model. A multi-fractional approach with five grain-size fractions between 150 and 450 μm allows for the simulation of corresponding surface sediment grain-size distributions. Net sediment fluxes for distinct conditions are identified: during storm conditions, bed load sediment transport is generally onshore directed on the shallower ebb-tidal delta shoals, whereas fine-grained suspended sediment bypasses the tidal inlet by wave-driven currents. During fair weather the sediment transport mainly focuses on the inlet throat and the marginal flood channels. We show how the observed sediment grain-size distribution and the morphological response at mixed-energy tidal inlets are the result of both wave-dominated less frequent storm conditions and mid-term, tide-dominant fair-weather conditions.