This study has hypothesized that for many rivers the trade‐off between flow accumulation and the decrease in slope along channel length means that stream power increases downstream and, moreover, that given the low slope angles in headwater and low‐order streams, they would have insufficient stream power to erode let alone transport sediment. The study considered the stream power profile, the particle travel distances and the application of the Hjulström curve based on the velocity profile of nine, large UK catchments. The study showed that:

1. Some rivers never showed a maximum in their longitudinal stream power profile, implying that some rivers never develop a deposition zone before they discharge at the tidal limit.
2. Particle travel distances during a bankfull discharge event showed that for some rivers 91% of the upper main channel would not be cleared of sediment. Furthermore, while some rivers could transport a 2 mm particle their entire length in one bankfull event, for another river it would take 89 such events.
3. The Hjulström curve shows that for three of the study rivers the upper 20 km of the river was not capable of eroding a 2 μm particle.
4. The study has shown that for all rivers studied, erosion is focused downstream and deposition upstream. Many UK rivers have a dead zone where, on time scales of the order of centuries, no erosion or transport occurs and erosion only occurs in the lower courses of the channel where discharge rather than slope dominates – we propose these as underpowered rivers.

© 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd

中文翻译：

---

河流动力不足的问题

这项研究假设，对于许多河流，流量积聚与沿河道长度的坡度减小之间的折衷意味着河流下游的水力增加，而且，考虑到源头水位和低阶水流的坡度较低，流力不足以侵蚀，更不用说运输泥沙了。这项研究基于英国9个大型流域的速度分布图，考虑了河流的功率分布图，粒子的行进距离以及Hjulström曲线的应用。研究表明：

1. 一些河流从未在其纵向河流功率剖面上显示出最大值，这意味着某些河流在达到潮汐极限之前从未开发出沉积带。
2. 一次满溢排放过程中的颗粒传播距离表明，对于某些河流，上游主干道的91％不会清除沉积物。此外，尽管某些河流可能在一次河堤满满事件中运输全长2毫米的颗粒，但对于另一条河流，则需要进行89次此类事件。
3. Hjulström曲线显示，对于其中三个研究河流，河流的上游20 km不能腐蚀2μm的颗粒。
4. 研究表明，对于所研究的所有河流，侵蚀集中在下游，而沉积则在上游。英国的许多河流都有一个死区，在几个世纪的时间尺度上，没有发生侵蚀或运输，并且侵蚀仅发生在河道的下游，那里的流量以坡度为主，而不是坡度。我们建议这些河流为动力不足的河流。

©2020作者。约翰·威利父子有限公司出版的《地球表面过程和地形》