Flow chutes in Fowlers Creek, arid western New South Wales, Australia : Evidence for diversity in the influence of trees on ephemeral channel form and process
Flow chutes in Fowlers Creek, arid western New South Wales, Australia : Evidence for diversity in the influence of trees on ephemeral channel form and process
复制标题
澳大利亚新南威尔士州西部干旱地区福勒斯溪的流槽：树木对短暂河道形式和过程影响多样性的证据
DOI：
10.1016/j.geomorph.2008.05.004
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发表时间：
2008
期刊：
影响因子：
3.9
通讯作者：
D. Dunkerley
中科院分区：
文献类型：
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作者：
D. Dunkerley
本文确定了一个河流地貌，流槽，从福勒溪，在澳大利亚新南威尔士州西部的一个短暂的流。在这条河流上，有对比鲜明的配置通道边缘和通道床植被（通道相关植被）。在最常见的河道类型中，大型赤桉树生长在河床和河岸上，导致河道糙率较高。然而，在一些约0.5公里长的河段中，没有树木生长在中岸高度以下。河床保持完全无植物生长，河道变窄至紧靠上游和下游的相邻河段宽度的三分之一或更少。粗端的推移质颗粒大小的人口是不代表在这些狭窄的河段，表明粗颗粒有效地通过他们，超越较细的沉积物。这些河段明显地经历比通道的其余部分更高的流速，在此被称为流动斜槽。它们内部的河床物质经常像沙丘一样移动，这些沙丘在洪水消退后仍然存在。每个泄流槽的末端都有一个反向的河床坡度，在终点下游，河道变宽，导致粗推移质以砾石和卵石坝的形式沉积。反向河床斜坡将水滞留在流槽中，流槽在洪水事件发生后的几个月内仍然是主要的水池或水坑。大而明显古老的树木衬流槽意味着这些通道功能是稳定的，超过102- 103年的时期，与行为的河段与植被床，银行侵蚀和局部横向通道迁移和/或扩大是活跃的。因此，流槽似乎是稳定、平衡的河流地貌。
This paper identifies a fluvial landform, the flow chute, from Fowlers Creek, an ephemeral stream in western New South Wales, Australia. On this stream there are contrasting configurations of channel-margin and channel-bed vegetation (channel-associated vegetation). In the most common type of channel reach, large Eucalyptus camaldulensis trees grow on the bed and banks, and contribute to high channel roughness. In some reaches of about 0.5 km length, however, no trees grow below mid-bank height. The bed remains completely unvegetated, and the channel narrows to one third or less of the width of adjoining reaches immediately upstream and downstream. The coarse end of the bedload grain size population is not represented in these narrow reaches, indicating that the coarsest grains are efficiently moved through them, overpassing finer sediments. These reaches evidently experience higher flow speeds than the remainder of the channel, are here termed flow chutes. The bed material within them is often moved as dunes that remain upon flood recession. Each flow chute ends with a reverse bed slope and just downstream of the terminus the channel widens, resulting in the deposition of coarse bed load in the form of gravel and cobble bars. The reverse bed slope detains water in the flow chutes, which remain as major pools or waterholes for months following flood events. The large and apparently old trees lining the flow chutes imply that these channel features are stable over periods of 102–103years, in contrast with the behaviour of reaches with vegetated beds, where bank erosion and local lateral channel migration and/or widening are active. Flow chutes thus appear to be stable, equilibrium fluvial landforms.