...
  • 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 >A decadal-scale numerical model for wandering, cobble-bedded rivers subject to disturbance
【24h】

A decadal-scale numerical model for wandering, cobble-bedded rivers subject to disturbance

机译：徘徊的二等规模数值模型，鹅卵石卧系受到干扰的影响

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

Alluvial rivers are composed of self-formed channels which are sensitive to disturbances in their flow and sediment-supply regimes. Regime changes commonly occur over decadal and longer timescales and can be caused by anthropogenic alterations such as dam construction and removal. Advances in numerical modeling have increased our ability to explore geomorphic adjustments over long timescales; however, many models designed to be run for decades or longer assume that banks are immovable or that channel width is constant. Since river channels often respond to disturbance by adjusting their geometry, this is a significant shortcoming. To investigate the impact of long-term sediment supply alterations on channel geometry and stability, we have adapted MAST-1D, a reach-scale bed evolution model, to incorporate functions for bank erosion, vegetation encroachment, and local avulsions. The model is designed for medium-large, coarse multithreaded rivers and can be run over long (decades-centuries) timescales. Bank erosion is a function of the mobility and transport capacity for structurally-important grains which protect the bank toe. Vegetation growth is proportional to point bar width and occurs during conditions of low shear stress. Local avulsions occur when aggradation causes channel depth to drop below a threshold. We apply the model to the Elwha River in Washington, USA with the goal of investigating if and when the river recovers from dam emplacement and removal. The Elwha was dammed for nearly 100 years, and then two dams were removed, releasing a large pulse of sediment. We have modeled the set of reaches between the two dams. Our simulations suggest that channel response to dam emplacement occurs gradually over several decades but that the channel recovers to near pre-dam conditions within about a decade following the removal. The dams leave a lasting legacy on the floodplain, which does not completely recover, even after two centuries. (c) 2020 John Wiley & Sons, Ltd.
机译：冲积河流由自成的通道组成，对流动和沉积物制度的干扰敏感。政权变化通常发生在Decadal和更长的时间尺度上，并且可以由诸如DAM构造和去除等人的人为改变引起的。数值模型的进步提高了我们探索长时间尺度的地貌调整的能力;然而，许多设计用于数十年或更长的型号假设银行是不可移动的或通道宽度是恒定的。由于河流渠道经常通过调整其几何形状来响应干扰，这是一个重要的缺点。为了调查长期沉积物供应改变对通道几何形状和稳定性的影响，我们已经改编了桅杆1D，达拉级床演变模型，融合了银行侵蚀，植被侵蚀和局部撕脱的函数。该模型专为中型粗糙的多线程河流设计，可以长（数百世纪）时间尺寸。银行侵蚀是在结构上重要谷物的移动和运输能力的函数，这些谷物保护银行脚趾。植被生长与点杆宽度成比例，并且在低剪切应力的条件下发生。当聚合导致通道深度降至低于阈值时，会发生局部撕脱。我们将该模型应用于美国华盛顿的Elwha河，其目标是在河流从坝进出和移除时调查。 ELWHA被占据了近100年的近100年，然后去除了两个水坝，释放了大量沉积物。我们已经建模了两个水坝之间的到达。我们的模拟表明，在几十年内逐渐发生渠道响应逐渐发生，但频道在移除后大约十年内恢复到坝前条件附近。大坝留下了洪泛平原的持久遗产，即使在两个世纪之后也不会完全恢复。 （c）2020 John Wiley＆Sons，Ltd。

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