Geomorphic effects of wood in rivers
Geomorphic effects of wood in rivers
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河流中木材的地貌效应
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
T. Abbe
中科院分区：
文献类型：
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作者：
D. Montgomery;B. Collins;J. Buffington;T. Abbe
——数百万年来，木材一直落入河流，对河道过程产生局部影响，并在广泛的时空尺度上对河道形态和动态产生综合影响。稳定的木块对当地河道水力和沉积物输送的影响可能会影响河岸侵蚀的速度，形成水池，或引发沉积物沉积和沙坝形成。在更大的空间尺度上，大木材供应的变化会引发河流河段形态以及河流与其漫滩之间相互作用的变化。在很长一段时间内，与木材贫乏的河道相比，木材丰富的河流可能会保留更多的沉积物，并且具有较低的沉积物输送速率和更陡的坡度。河流中木材的大部分地貌效应都来自于大型、稳定的原木，这些原木催化了较小木材和沉积物的路线和储存的变化。原木相对于河道的尺寸可以合理衡量河道内木材的潜在稳定性。具有大量潜在稳定木材供应的河道可能会经历独立于外部强迫（例如气候变化、沉积物供应的时间变化或构造活动）的床高程的显着垂直变化。在一些河流系统中，木材状况的变化（通过供应到河流的木材的大小和数量来描述）可能产生与沉积物供应或排放状况变化所产生的影响一样大的影响。因此，了解木材的地貌效应对于评估森林河道的状况和潜在反应至关重要。
—Wood has been falling into rivers for millions of years, resulting in both local effects on channel processes and integrated influences on channel form and dynamics over a wide range of spatial and temporal scales. Effects of stable pieces of wood on local channel hydraulics and sediment transport can influence rates of bank erosion, create pools, or initiate sediment deposition and bar formation. At larger spatial scales, changes in the supply of large wood can trigger changes in both river-reach morphology and the interaction between a river and its floodplain. Over long time scales, wood-rich rivers may retain more sediment and have lower sediment transport rates and steeper slopes than comparable wood-poor channels. Most geomorphic effects of wood in rivers arise from large, stable logs that catalyze changes in the routing and storage of both smaller wood and sediment. The size of a log relative to the channel provides a reasonable gauge of the potential stability of in-channel wood. Channels with a high supply of large, potentially stable wood may experience substantial vertical variability in bed elevation independent from external forcing (e.g., climate variability, temporal variations in sediment supply, or tectonic activity). In some river systems, changes in the wood regime, as described by the size and amount of wood supplied to a river, can result in effects as great as those arising from changes in the sediment supply or the discharge regimes. Consequently, an understanding of the geomorphic effects of wood is crucial for assessing the condition and potential response of forest channels.