Fine bed material in pools of natural gravel bed channels
Fine bed material in pools of natural gravel bed channels
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天然砾石床河道池中的细床材料
DOI：
10.1029/1998wr900088
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发表时间：
1999
影响因子：
5.4
通讯作者：
S. Hilton
中科院分区：
文献类型：
--
作者：
T. Lisle;S. Hilton
天然砾石河床通道通常含有细砂和细砾石，填充粗砾石河床框架的空隙。如果细床物质的供应超过了骨架空隙的储存能力，则多余的细床物质形成表层斑块，在低流量期间，这些斑块在池中可能是大量的。在北方加州和南俄勒冈州的34个天然河道中收集的数据表明：(1)床面上的细料可以很容易地以高的颗粒速度被扬筛和输送，其中大部分处于间歇悬浮状态。细料可以主导砾石河床河道中的床料负荷，但其在床面上的丰度受到其流动性增加的限制，因为隐藏在突出颗粒之间的地方被填充。(2)池中的精细材料通常每年更换多次。(3)在母质产生丰富的桑迪沉积物的河道中，细床物质填充的剩余池体积的比例V* 与年产沙量相关。(4)V* 的时空变化似乎与泥沙输入和水排放之间的平衡变化相对应。这些结果表明，V* 可用于监测和评价砾石河床通道中过量细粒物质的供应，并且池中细粒物质的样品可表征细的、移动的床物质负荷模式。
Natural gravel bed channels commonly contain a fine mode of sand and fine gravel that fills voids of the bed framework of coarser gravel. If the supply of fine bed material exceeds the storage capacity of framework voids, excess fine material forms surficial patches, which can be voluminous in pools during low flow. Data collected in 34 natural channels in northern California and southern Oregon indicate the following. (1) Fine material on the bed surface can be readily winnowed and transported at high particle velocities, much of it in intermittent suspension. Fine material can dominate the bed material load in gravel bed channels, but its abundance on the bed surface is limited by its increasing mobility as hiding places among prominent particles are filled. (2) Fine material in pools is typically replaced many times per year. (3) The proportion V* of residual pool volume filled with fine bed material correlates with annual sediment yield in channels whose parent material produces abundant sandy sediment. (4) Temporal and spatial changes in V* appear to correspond to variations in the balance between sediment inputs and water discharge. These results suggest that V* can be used to monitor and evaluate the supply of excess fine material in gravel bed channels and that samples of fine material in pools can characterize the fine, mobile mode of bed material load.