Integrated UAS and LiDAR reveals the importance of land cover and flood magnitude on the formation of incipient chute holes and chute cutoff development
Integrated UAS and LiDAR reveals the importance of land cover and flood magnitude on the formation of incipient chute holes and chute cutoff development
复制标题
DOI：
10.1002/esp.4816
复制
发表时间：
2020-01
影响因子：
3.3
通讯作者：
Q. Lewis;D. Edmonds;B. Yanites
中科院分区：
文献类型：
--
作者：
Q. Lewis;D. Edmonds;B. Yanites
蜿蜒的河流弯曲度增加，直到河道侵蚀到自身(颈部截断)或在泛滥平原上形成一条新的河道(斜槽截断)，弯曲度减小。不同于可以在不考虑越岸过程的情况下进行测量或建模的颈部截流，斜槽截流必须至少部分地由滩地上的河道形成过程控制。尽管溜槽切断控制着蜿蜒的河流形态，但引起溜槽切断的过程还不是很清楚。这项研究利用基于高时间和空间分辨率的UAS激光雷达和航空摄影技术，分析了美国印第安纳州东福克怀特河沿岸两个早期降落伞的形态。1998年至2019年间获得的激光雷达和航空图像显示，在降落伞通道启动后的某个时间，两个降落伞的中心都形成了巨大的冲刷洞。研究分水岭内更大的分析表明，初期滑槽内的冲刷洞可能是稳定的，也可能是不稳定的，当滑槽被当地植被和森林殖民时，冲刷坑往往是稳定的。农田滩地冲刷坑形成后，冲刷坑在初始形成后迅速扩大，有助于完全截断溜槽。此外，这项研究表明，冲刷坑的形成可能是对常见的、相对较低等级的洪水的响应，而且初期冲刷槽的侵蚀量并不取决于洪峰等级。冲刷洞在扩大溜槽河道中的作用可能是曲折河流中溜槽河道演变的一个重要机制。这项研究还证实，通过集成的UAS和LiDAR等按需遥感技术，对流量、土地覆盖和截止形态之间的关系的理解得到了实质性的改善。©2020 John Wiley&Sons，Ltd.
Meandering river sinuosity increases until the channel erodes into itself (neck cutoff) or forms a new channel over the floodplain (chute cutoff) and sinuosity is reduced. Unlike neck cutoff, which can be measured or modelled without considering overbank processes, chute cutoff must be at least partially controlled by channel‐forming processes on the floodplain. Even though chute cutoff controls meandering river form, the processes that cause chute cutoff are not well understood. This study analyses the morphology of two incipient chute cutoffs along the East Fork White River, Indiana, USA, using high temporal and spatial resolution UAS‐based LiDAR and aerial photography. LiDAR and aerial imagery obtained between 1998 and 2019 reveals that large scour holes formed in the centre of both chutes sometime after chute channel initiation. A larger analysis within the study watershed reveals that scour holes within incipient chutes can be stable or unstable, and tend to stabilize when the chute is colonized by native vegetation and forest. When the scour holes form in farmed floodplain, they enlarge rapidly after initial formation and contribute to complete chute cutoff. In addition, this study shows that the formation of scour holes can occur in response to common, relatively low‐magnitude floods and that the amount of incipient chute erosion does not depend on peak flood magnitude. The role of scour holes in enlarging chute channels could be an important mechanism for chute channel evolution in meandering rivers. This study also confirms that understanding the relationships among flow, land cover, and cutoff morphology is substantially improved with on‐demand remote sensing techniques like integrated UAS and LiDAR. © 2020 John Wiley & Sons, Ltd.