Upstream perturbation and floodplain formation effects on chute‐cutoff‐dominated meandering river pattern and dynamics
Upstream perturbation and floodplain formation effects on chute‐cutoff‐dominated meandering river pattern and dynamics
复制标题
上游扰动和漫滩形成对以滑槽截流为主的曲流河格局和动力学的影响
DOI：
10.1002/esp.4638
复制
发表时间：
2019
影响因子：
3.3
通讯作者：
Kleinhans Maarten G.
中科院分区：
文献类型：
--
作者：
Weisscher Steven A. H.;Shimizu Yasuyuki;Kleinhans Maarten G.
一个持续的动态入流扰动和酒吧漫滩转换被认为是至关重要的动态曲流。过去的实验、一维模型和线性理论已经证明，动态弯曲的开始和持续需要流入的周期性横向运动。然而，它仍然是未知的流入扰动的周期是否影响自我形成的曲折动力学。在这里，我们数值研究的流入扰动期的发展和蜿蜒动力学的斜槽截止为主的河流，这需要二维建模与植被形成河漫滩酒吧的影响。我们扩展了形态动力学模型Nays2D与植被的生长和死亡率的规则，允许蜿蜒。我们通过改变运行之间的扰动周期（在典型建模的曲折周期周围的一个数量级上）来测试横向迁移流入边界的影响。从一个直的通道初始曲流形成后的截止级联，所有运行有足够的植被显示出一系列的增长曲折终止溜槽截止。这产生了一个复杂的河道带地形，点坝复合体被斜槽、牛轭湖和与滚动条相关的植被年龄模式截断。从固有的生物形态反馈回路中产生的弯曲度、编织指数和曲流周期与流入扰动周期无关，尽管对于弱的和不存在的流入扰动，旋转到动态平衡需要更长的时间和距离。这就解释了为什么，在以前的实验研究中，动态蜿蜒只完成了持续的上游扰动水槽是短相对于蜿蜒的波长。我们对自生曲流模式的建模证明，以涡条为主的曲流和以斜槽截止为主的曲流是由下游对流不稳定性发展而来的。这一见解延伸到更多的河流，河口和海岸系统的形态模型和实验，这需要持续的动态扰动，形成复杂的模式和发展自然动态。版权所有2019作者。地球表面过程和地貌由约翰威利父子有限公司出版。
A sustained dynamic inflow perturbation and bar–floodplain conversion are considered crucial to dynamic meandering. Past experiments, one‐dimensional modelling and linear theory have demonstrated that the initiation and persistence of dynamic meandering require a periodic transverse motion of the inflow. However, it remains unknown whether the period of the inflow perturbation affects self‐formed meander dynamics. Here, we numerically study the effect of the inflow perturbation period on the development and meander dynamics of a chute‐cutoff‐dominated river, which requires two‐dimensional modelling with vegetation forming floodplain on bars. We extended the morphodynamic model Nays2D with growth and mortality rules of vegetation to allow for meandering. We tested the effect of a transversely migrating inflow boundary by varying the perturbation period between runs over an order of magnitude around typical modelled meander periods. Following the cutoff cascade after initial meander formation from a straight channel, all runs with sufficient vegetation show series of growing meanders terminated by chute cutoffs. This generates an intricate channel belt topography with point bar complexes truncated by chutes, oxbow lakes, and scroll‐bar‐related vegetation age patterns. The sinuosity, braiding index and meander period, which emerge from the inherent biomorphological feedback loops, are unrelated to the inflow perturbation period, although the spin‐up to dynamic equilibrium takes a longer time and distance for weak and absent inflow perturbations. This explains why, in previous experimental studies, dynamic meandering was only accomplished with a sustained upstream perturbation in flumes that were short relative to the meander wavelength. Our modelling of self‐formed meander patterns is evidence that scroll‐bar‐dominated and chute‐cutoff‐dominated meanders develop from downstream convecting instabilities. This insight extends to many more fluvial, estuarine and coastal systems in morphological models and experiments, which require sustained dynamic perturbations to form complex patterns and develop natural dynamics. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.
登录
查看更多内容
影响因子：
3.3
作者：
M. Kleinhans;B. de Vries;L. Braat;M. van Oorschot
通讯作者：
M. Kleinhans;B. de Vries;L. Braat;M. van Oorschot
影响因子：
3.3
作者：
Nicholas A
通讯作者：
Nicholas A
RIP 通道的建模形成和随后的非线性演化：时变波强迫与时不变波强迫
影响因子：
2
作者：
B. Castelle;B. Ruessink
通讯作者：
B. Ruessink
蜿蜒河流动态
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
S. Weiss
通讯作者：
S. Weiss
影响因子：
12.1
作者：
Kleinhans, Maarten G.;van Dijk, Wout M.;Cheshier, Nathan
通讯作者：
Cheshier, Nathan