Coarse sediment transport in mountain streams in Colorado and Wyoming, USA
Coarse sediment transport in mountain streams in Colorado and Wyoming, USA
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美国科罗拉多州和怀俄明州山溪中的粗沉积物输送
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发表时间：
2005
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通讯作者：
C. Troendle
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作者：
Sandra E. Ryan;L. Porth;C. Troendle
自20世纪90年代初以来，美国林业局的研究人员在美国科罗拉多州和怀俄明州的陡峭粗沙河道中进行了数千次泥沙测量。在本文中，我们使用19个站点的数据来描述各种渠道类型和大小的粗泥沙输移模式和输沙率，包括阶梯式、平底式、池式冲刷式和近辫式。这项工作建立在以前工作的基础上，我们应用分段回归模型来(1)将水流与推移质输沙率联系起来，(2)定义粗粒河道中的输沙阶段。早些时候，科罗拉多州弗雷泽附近的弗雷泽实验森林的八个地点的泥沙负荷数据对该模型进行了测试。分析表明，对这些数据以及应用了该程序的四个补充渠道的数据都有良好的适用性。然而，早期的结果是从大多数具有非常相似的地质和径流制度的地点收集的数据得出的。在本文中，我们进一步评估了分段回归在具有更大范围地貌条件的渠道数据中的应用。这一结果与以前工作的结果是一致的，因为在一个相对较窄的排放范围内，推移质输运的性质发生了实质性的变化。从最初的低输沙率(第一阶段)向较高的输沙率(第二阶段)过渡，平均发生在约80%的岸上(1.5年重现间隔)流量。对这两个阶段移动的颗粒大小的比较表明，在第一阶段运输期间，粗砾石很少被困在取样器中。此外，床面D16至D25颗粒的移动和捕获似乎与II相输送的开始相一致，特别是在具有基本静态通道表面的系统中。然而，虽然在19个研究地点观测到的推移质输送模式有许多相似之处，但每个地点都有自己的“推移质信号”，因为输送的泥沙的速度和大小在很大程度上反映了该系统特有的水流和泥沙的性质。2005年由约翰·威利父子有限公司出版。
Since the early 1990s, US Forest Service researchers have made thousands of bedload measurements in steep, coarse‐grained channels in Colorado and Wyoming, USA. In this paper we use data from 19 of those sites to characterize patterns and rates of coarse sediment transport for a range of channel types and sizes, including step–pool, plane‐bed, pool–riffle, and near‐braided channels. This effort builds upon previous work where we applied a piecewise regression model to (1) relate flow to rates of bedload transport and (2) define phases of transport in coarse‐grained channels. Earlier, the model was tested using bedload data from eight sites on the Fraser Experimental Forest near Fraser, Colorado. The analysis showed good application to those data and to data from four supplementary channels to which the procedure was applied. The earlier results were, however, derived from data collected at sites that, for the most part, have quite similar geology and runoff regimes. In this paper we evaluate further the application of piecewise regression to data from channels with a wider range of geomorphic conditions. The results corroborate with those from the earlier work in that there is a relatively narrow range of discharges at which a substantial change in the nature of bedload transport occurs. The transition from primarily low rates of sand transport (phase I) to higher rates of sand and coarse gravel transport (phase II) occurs, on average, at about 80 per cent of the bankfull (1·5‐year return interval) discharge. A comparison of grain sizes moved during the two phases showed that coarse gravel is rarely trapped in the samplers during phase I transport. Moreover, the movement and capture of the D16 to D25 grain size of the bed surface seems to correspond with the onset of phase II transport, particularly in systems with largely static channel surfaces. However, while there were many similarities in observed patterns of bedload transport at the 19 studied sites, each had its own ‘bedload signal’ in that the rate and size of materials transported largely reflected the nature of flow and sediment particular to that system. Published in 2005 by John Wiley & Sons, Ltd.