...
  • 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 >Chute channel dynamics in large, sand-bed meandering rivers
【24h】

Chute channel dynamics in large, sand-bed meandering rivers

机译：大型河床蜿蜒河道的溜槽动力学

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

Meander bends of many large, sand-bed meandering rivers are partitioned by chute channels that convey permanent flow, and co-exist with the mainstem for decades. As a first step toward understanding the dynamics and morphodynamic implications of these 'bifurcate meander bends', this study applied binary logistic regression analysis to determine whether it is possible to predict chute initiation based on attributes of meander bend character and dynamics. Regression models developed for the Strickland River, Papua New Guinea, the lower Paraguay River, Paraguay/Argentina, and the Beni River, Bolivia, revealed that the probability of chute initiation at a meander bend is a function of the bend extension rate (the rate at which a bend elongates in a direction perpendicular to the valley axis trend). Image analyses of all rivers and field observations from the Strickland suggest that the majority of chute channels form during scroll-slough development. Rapid extension is shown to favour chute initiation by breaking the continuity of point bar deposition and vegetation encroachment at the inner bank, resulting in widely-spaced scrolls with intervening sloughs that are positively aligned with primary over-bar flow. The rivers plot in order of increasing chute activity on an empirical meandering-braided pattern continuum defined by potential specific stream power (ω _(pv)) and bedload calibre (D _(50)). Increasing stream power is considered to result in higher bend extension rates, with implications for chute initiation. In addition, chute stability is shown to depend on river sediment load relative to flow discharge (Qs/Q), such that while the Beni may plot in the region of highly braided rivers by virtue of a high potential specific stream power, the formation of stable chute channels is suppressed by the high sediment load. This tendency is consistent with previous experimental studies, and results in a planform that is transitional between single-thread meandering and braided.
机译：许多大型沙床曲折河的曲折弯被滑槽分隔，这些滑槽输送了永久的水流，并与干流共存了数十年。作为了解这些“分叉弯道”的动力学和形态动力学影响的第一步，本研究应用了二进制逻辑回归分析来确定是否有可能基于弯道特征和动力学特性来预测滑道的启动。针对斯特里克兰河，巴布亚新几内亚，巴拉圭下游，巴拉圭/阿根廷和玻利维亚的贝尼河建立的回归模型显示，弯道弯道滑道启动的可能性是弯道延伸率的函数（弯曲沿垂直于谷轴趋势的方向延伸的位置）。对所有河流的图像分析和斯特里克兰地区的野外观测表明，大部分涡流槽形成于涡旋-泥沼发育过程中。快速延伸显示出通过破坏点状杆沉积和内岸植被侵蚀的连续性而有利于滑道的形成，从而导致涡旋间隙宽且中间带有与主要的超杆流动正向对齐的泥浆。河流按照由潜在比流功率（ω_（pv））和床载口径（D _（50））定义的经验曲折编织图案连续体上的滑道活动增加顺序绘制。流功率的增加被认为会导致更高的弯曲延伸率，从而影响滑道的启动。此外，滑道的稳定性还取决于相对于流量排放（Qs / Q）的河流泥沙负荷，因此，尽管贝尼河可能会凭借高的潜在比流功率而在辫状河流的区域作图，高的泥沙量抑制了稳定的溜槽通道。这种趋势与以前的实验研究相一致，并导致在单线曲折和编织之间过渡的平面形式。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
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