Scroll bars are inner bank levees along meandering river bends
Scroll bars are inner bank levees along meandering river bends
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滚动条是沿着蜿蜒河湾的内岸堤坝
DOI：
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发表时间：
2019
影响因子：
3.3
通讯作者：
D. Mohrig
中科院分区：
文献类型：
--
作者：
J. Mason;D. Mohrig
使用LiDAR数据以及分布在整个调查区域的一系列11条沟渠研究了美国德克萨斯州Trinity河65公里长的滚动条。我们的结论是，滚动条是堤坝沉积沿着这些曲折的河流弯曲的内银行。滚动条波峰被发现有类似的海拔外银行堤坝波峰，这意味着他们的建设功能，创造积极的地形起伏以上的河漫滩的海拔。沟槽揭示了滚动条是由再加工的悬浮沉积物建造的，具有常见涟漪尺度交叉分层、平面纹层和泥质生物扰动层-这些特征通常与其他系统中的堤坝沉积有关。激光雷达对洪水期间河床物质输送对滚动条的侵蚀的观察表明，滚动条间距对于估计总体河道迁移率来说是一个不完美的代表。此外，具有沙丘尺度交叉分层的较粗沉积物的散布透镜体代表了这些侵蚀事件的地层记录，并表明滚动条的河道边缘的侵蚀并不罕见。滚动条不太可能被保存下来，因为它们平均只占内岸总地形的12%。我们认为，错误识别的点酒吧横向吸积表面作为滚动条是常见的，并可能导致重建通道属性的问题，由于点酒吧和滚动条平面形状的几何形状之间的系统差异。© 2019 John Wiley & Sons，Ltd.版权所有。
Scroll bars across a 65‐km stretch of the Trinity River in Texas, USA were studied using LiDAR data as well as with a series of 11 trenches spread out across the survey area. We conclude that scroll bars are levees that are deposited along the inner banks of these meandering river bends. Scroll bar crests were found to have similar elevations to those of outer bank levee crests, implying that they are constructional features that create positive topographic relief above the elevation of the floodplain. Trenches reveal that scroll bars are built from reworked suspended sediment, with common ripple‐scale cross stratification, planar laminations and muddy bioturbated layers – characteristics often associated with levee sedimentation in other systems. LiDAR observation of the erosion of scroll bars by bed material transport during flood implies that scroll bar spacing is an imperfect proxy for estimating overall channel migration rates. In addition, interspersed lenses of coarser sediment with dune‐scale cross stratification represent the stratigraphic record of these erosional events and suggest that erosion of the channel‐ward edge of the scroll bar is not uncommon. Preservation of scroll bars is unlikely, given that they are responsible for an average of only the uppermost 12% of the total inner bank relief. We suggest that misidentification of point bar lateral accretion surfaces as scroll bars is common and can lead to issues with reconstructing channel properties due to systematic differences between point bar and scroll bar planform geometries. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.
影响因子：
12.1
作者：
J. Lewin;P. Ashworth
通讯作者：
J. Lewin;P. Ashworth