Nearshore shore-oblique bars, gravel outcrops, and their correlation to shoreline change
Nearshore shore-oblique bars, gravel outcrops, and their correlation to shoreline change
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DOI：
10.1016/j.margeo.2006.08.007
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发表时间：
2006-11
期刊：
影响因子：
2.9
通讯作者：
C. Schupp;J. McNinch;J. List
中科院分区：
文献类型：
--
作者：
C. Schupp;J. McNinch;J. List
这项研究表明，在北卡罗来纳州州的北方外滩沿着的碎波带的海岸斜砂坝和砾石露头的物理并发。这些水下特征在空间上与海岸线的变化在一系列的时间和空间尺度。以前的研究已经注意到海滩冲浪区的相互作用的存在，但在一般情况下，近岸地质特征和海岸变化之间的关系知之甚少。这些新的发现应考虑在探索海岸带动态和开发预测工程模型。外滩的碎波带和近岸区域主要是平面和桑迪，但也有几个离散区域，其中有海岸斜坝和散布的砾石露头。这些酒吧领域有救济高达3米，是几公里宽，并在1.5年的调查期间相对静止，但是，在这段时间内，酒吧领域的shoreward组件确实表现出变化。在研究区域，40公里的沿岸长度，观察到的所有砾石露头，位于附近的海岸斜酒吧，在槽的宽度和长度类似的相关酒吧。地震勘测表明，这些露头是活动地表砂层下面的砾石层的一部分。互相关分析表明，每月和几十年的海岸线变化率与邻近的冲浪区水深和沉积物分布的高度相关性。在区域上，海岸斜砂坝和砾石露头的地区与短期海岸线变化率高和长期海岸线变化率高的岸上地区相关。在长期的海岸线侵蚀的主要高峰是岸边的斜向沙坝，但并不是所有的地区与长期的海岸线变化率高的斜向沙坝和槽。
This study demonstrates the physical concurrence of shore-oblique bars and gravel outcrops in the surf zone along the northern Outer Banks of North Carolina. These subaqueous features are spatially correlated with shoreline change at a range of temporal and spatial scales. Previous studies have noted the existence of beach-surf zone interactions, but in general, relationships between nearshore geological features and coastal change are poorly understood. These new findings should be considered when exploring coastal zone dynamics and developing predictive engineering models. The surf zone and nearshore region of the Outer Banks is predominantly planar and sandy, but there are several discrete regions with shore-oblique bars and interspersed gravel outcrops. These bar fields have relief up to 3 m, are several kilometers wide, and were relatively stationary over a 1.5 year survey period; however, the shoreward component of the bar field does exhibit change during this time frame. All gravel outcrops observed in the study region, a 40 km longshore length, were located adjacent to a shore-oblique bar, in a trough that had width and length similar to that of the associated bar. Seismic surveys show that the outcrops are part of a gravel stratum underlying the active surface sand layer. Cross-correlation analyses demonstrate high correlation of monthly and multi-decadal shoreline change rates with the adjacent surf-zone bathymetry and sediment distribution. Regionally, areas with shore-oblique bars and gravel outcrops are correlated with on-shore areas of high short-term shoreline variability and high long-term shoreline change rates. The major peaks in long-term shoreline erosion are onshore of shore-oblique bars, but not all areas with high rates of long-term shoreline change are associated with shore-oblique bars and troughs.