...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Tidal channel meander formation by depositional rather than erosional processes: examples from the prograding Skagit River Delta (Washington, USA)
【24h】

Tidal channel meander formation by depositional rather than erosional processes: examples from the prograding Skagit River Delta (Washington, USA)

机译：通过沉积而非侵蚀过程形成潮汐河道曲折：来自不断发展的Skagit河三角洲的实例（美国华盛顿）

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Channel meander dynamics in fluvial systems and many tidal systems result from erosion of concave banks coupled with sediment deposition on convex bars. However, geographic information system (GIS) analysis of historical aerial photographs of the Skagit Delta marshes provides examples of an alternative meander forming process in a rapidly prograding river delta: deposition-dominated tidal channel meander formation through a developmental sequence beginning with sandbar formation at the confluence of a blind tidal channel and delta distributary, proceeding to sandbar colonization and stabilization by marsh vegetation to form a marsh island opposite the blind tidal channel outlet, followed by narrowing of the gap between the island and mainland marsh, closure of one half of the gap to join the marsh island to the mainland, and formation of an approximately right-angle blind tidal channel meander bend in the remaining half of the gap. Topographic signatures analogous to fluvial meander scroll bars accompany these planform changes. Parallel sequences of marsh ridges and swales indicate locations of historical distributary shoreline levees adjacent to filled former island/mainland gaps. Additionally, the location of marsh islands within delta distributaries is not random; islands are disproportionately associated with blind tidal channel/distributary confluences. Furthermore, blind tidal channel outlet width is positively correlated with the size of the marsh island that forms at the outlet, and the time until island fusion with mainland marsh. These observations suggest confluence hydrodynamics favor sandbar/marsh island development. The transition from confluence sandbar to tidal channel meander can take as little as 10 years, but more typically occurs over several decades. This depositional blind tidal channel meander formation process is part of a larger scale systemic depositional process of delta progradation that includes distributary elongation, gradient reduction, flow-switching, shoaling, and narrowing.
机译：河流系统和许多潮汐系统中的河道曲折动力学是由凹岸的侵蚀加上凸条上的沉积物造成的。然而，对Skagit三角洲沼泽历史航拍照片的地理信息系统（GIS）分析提供了在快速发展的三角洲中另一种曲折形成过程的示例：以发育为主的沉积序列为主的潮汐河道曲折形成，始于沙洲的形成。封闭潮汐河道和三角洲分布区，然后通过沼泽植被进行沙洲定居和稳定化，以形成一个与潮汐河道出口相对的沼泽岛，然后缩小该岛与大陆沼泽之间的缝隙，关闭一半的缝隙连接到沼泽岛到大陆，并在缝隙的其余一半处形成一个大约直角的盲潮道弯曲。这些平面变化伴随着类似于河流曲折滚动条的地形特征。沼泽山脊和沼泽的平行序列指示了历史性的分布海岸线堤防的位置，该堤防堤与已填充的前岛/大陆间隙之间相邻。另外，三角洲分流区内的沼泽岛的位置也不是随机的。岛屿与潮汐通道/分布汇合处的不成比例地相关。此外，潮汐通道出口的盲区宽度与在出口处形成的沼泽岛的大小以及与海岛与大陆沼泽融合的时间呈正相关。这些观察结果表明，汇流流体动力学有利于沙洲/沼泽岛的发展。从汇流沙洲到潮汐河道的过渡可能仅需10年，但更常见的是需要数十年的时间。该沉积式潮汐河道蜿蜒曲折形成过程是三角洲较大规模系统性沉积过程的一部分，该过程包括分布伸长，梯度减少，流量转换，浅滩和变窄。

著录项

相似文献

  • 外文文献
  • 中文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号