Geologic and physiographic controls on bed-material yield, transport, and channel morphology for alluvial and bedrock rivers, western Oregon
Geologic and physiographic controls on bed-material yield, transport, and channel morphology for alluvial and bedrock rivers, western Oregon
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俄勒冈州西部冲积河和基岩河流的底质产量、输送和河道形态的地质和地貌控制
DOI：
10.1130/b30831.1
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发表时间：
2012
影响因子：
4.9
通讯作者：
M. Keith
中科院分区：
文献类型：
--
作者：
J. O’Connor;J. Mangano;J. Mangano;S. Anderson;S. Anderson;J. R. Wallick;K. Jones;M. Keith
俄勒冈州西部的河流具有多种形式和特征，河道基底从连续的冲积砾石到裸露的基岩。分析了17条河流24个河谷河段的几个可测量的形态属性，为比较非冲积和冲积河道提供了依据。主要的区别是，冲积河段有更大的酒吧面积，更大的迁移率，并显示系统的相关性变量粒度床物质的运输能力。我们与这些通道类型之间的差异，床料输运率来自耦合区域分析的经验产沙量测量和物理实验的碎屑磨损在运输过程中。该沉积物供给分析表明，俄勒冈州西部的整体床料输运率主要受（1）岩性和盆地坡度控制，这是床料向水系供给的关键因素，以及（2）来自输运磨蚀和崩解的床料磨损的岩性控制。这种床料粉碎强烈影响床料运输在研究区，减少运输率的50%-90%沿着研究区的较大河流的长度。河床物质运输估计与形态分析的比较表明，冲积砾石河床通道的河床物质运输率和属性，如酒吧面积和当地的运输能力之间有系统的和绑定的关系。相比之下，很少有这样的关系是明显的非冲积河流基岩或混合床基板，这显然是更多的影响，由当地的控制渠道的几何形状和沉积物供应。在俄勒冈州西部的规模，河床物质供应和运输能力之间的平衡的自然地理和岩性的控制产生深远的影响，冲积和非冲积渠道的分布，因此，其独特的形态和行为的差异密切相关的理解河流响应构造和环境扰动，以及实施有效的恢复和监测策略。
The rivers of western Oregon have diverse forms and characteristics, with channel substrates ranging from continuous alluvial gravel to bare bedrock. Analysis of several measurable morphologic attributes of 24 valley reaches on 17 rivers provides a basis for comparing nonalluvial and alluvial channels. Key differences are that alluvial reaches have greater bar area, greater migration rates, and show systematic correlation among variables relating grain size to bed-material transport capacity. We relate these differences between channel types to bed-material transport rates as derived from a coupled regional analysis of empirical sediment yield measurements and physical experiments of clast attrition during transport. This sediment supply analysis shows that overall bed-material transport rates for western Oregon are chiefly controlled by (1) lithology and basin slope, which are the key factors for bed-material supply into the stream network, and (2) lithologic control of bed-material attrition from in-transport abrasion and disintegration. This bed-material comminution strongly affects bed-material transport in the study area, reducing transport rates by 50%–90% along the length of the larger rivers in the study area. A comparison of the bed-material transport estimates with the morphologic analyses shows that alluvial gravel-bed channels have systematic and bounding relations between bed-material transport rate and attributes such as bar area and local transport capacity. By contrast, few such relations are evident for nonalluvial rivers with bedrock or mixed-bed substrates, which are apparently more influenced by local controls on channel geometry and sediment supply. At the scale of western Oregon, the physiographic and lithologic controls on the balance between bed-material supply and transport capacity exert far-reaching influence on the distribution of alluvial and nonalluvial channels and their consequently distinctive morphologies and behaviors—differences germane for understanding river response to tectonics and environmental perturbations, as well as for implementing effective restoration and monitoring strategies.