Processes and rates of sediment and wood accumulation in headwater streams of the Oregon Coast Range, USA
Processes and rates of sediment and wood accumulation in headwater streams of the Oregon Coast Range, USA
复制标题
美国俄勒冈海岸山脉源头河流中沉积物和木材积累的过程和速率
DOI：
10.1002/esp.450
复制
发表时间：
2001
影响因子：
3.3
通讯作者：
R. Gresswell
中科院分区：
文献类型：
--
作者：
C. May;R. Gresswell
被泥石流冲刷至基岩的河道提供了独特的机会来计算低阶河流中沉积物和木材积累的速率，了解扰动后河道形态的时间序列，并对与沉积物输入和运输相关的过程进行推断。树木年代学用于估计俄勒冈州中部海岸山脉未测井盆地自上次泥石流以来的时间以及自上次林地更替火灾以来的时间。上次野火发生后的几十年里，泥石流活动比背景速度增加了 42%。对 13 条溪流的木材和沉积物储存变化进行了量化，这些溪流自上次泥石流发生以来 4 至 144 年不等。河道中木材和沉积物的体积以及基岩裸露的河道长度与上次泥石流发生的时间密切相关。木材增加了河道的存储能力，并截留了这些陡峭的源头溪流中的大部分沉积物。在没有木材的情况下，被泥石流冲刷到基岩的河道可能缺乏储存沉积物的能力，并且可能会在很长一段时间内保持基岩状态。在木材供应充足的情况下，低阶河道有可能在泥石流之间储存大量沉积物，可以作为山区沉积物的主要储存库之一。版权所有 © 2003 约翰·威利父子有限公司
Channels that have been scoured to bedrock by debris flows provide unique opportunities to calculate the rate of sediment and wood accumulation in low‐order streams, to understand the temporal succession of channel morphology following disturbance, and to make inferences about processes associated with input and transport of sediment. Dendrochronology was used to estimate the time since the previous debris flow and the time since the last stand‐replacement fire in unlogged basins in the central Coast Range of Oregon. Debris flow activity increased 42 per cent above the background rate in the decades immediately following the last wildfire. Changes in wood and sediment storage were quantified for 13 streams that ranged from 4 to 144 years since the previous debris flow. The volume of wood and sediment in the channel, and the length of channel with exposed bedrock, were strongly correlated with the time since the previous debris flow. Wood increased the storage capacity of the channel and trapped the majority of the sediment in these steep headwater streams. In the absence of wood, channels that have been scoured to bedrock by a debris flow may lack the capacity to store sediment and could persist in a bedrock state for an extended period of time. With an adequate supply of wood, low‐order channels have the potential of storing large volumes of sediment in the interval between debris flows and can function as one of the dominant storage reservoirs for sediment in mountainous terrain. Copyright © 2003 John Wiley & Sons, Ltd.