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首页> 外文期刊>River Research and Applications >FINE SEDIMENT INFILTRATION DYNAMICS IN A GRAVEL-BED RIVER FOLLOWING A SEDIMENT PULSE
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FINE SEDIMENT INFILTRATION DYNAMICS IN A GRAVEL-BED RIVER FOLLOWING A SEDIMENT PULSE

机译：泥沙脉动后碎石河流域细沙的渗透动力学

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Pulses of fine sediment in gravel-bedded rivers can cause extensive fine sediment infiltration (FSI) into void spaces in coarse bed material, potentially altering river morphodynamics and aquatic ecosystems. Previous work suggests a conceptual model of FSI whereby FSI occurs to a limited depth as a function of the relative grain size of bed sediment compared with infiltrating sediment and is influenced by fine sediment supply and local flow dynamics. Our study applies this conceptual model to a complex reach of a wandering, medium-sized, gravel-bed river to investigate the spatial and temporal controls on FSI. To constrain the timing of FSI, we use the release of contaminated sediment from an upstream dam removal and complementary field methods (bulk sampling, freeze cores and infiltration bags) to capture sediment across varied depositional settings. Our results indicate that, even in a morphologically complex reach, fine-sediment content in the bed does not vary significantly among deposition settings or vertically below the bed surface. We also found that the most contaminated fine sediments released into our study river by a dam removal are not present within the bed material and that substrate has likely been reworked over the period between the release of contaminated sediment and sampling. Our observations also suggest that seals of fine sediment causing void pore space at depth, which have previously been associated with FSI, are not evident in our field area. This suggests that in natural systems, high sediment supply and mobile beds may limit seal formation and persistence.
机译：砾石床河流中的细沙脉动会导致大量的细沙入渗（FSI）进入粗层物质中的空隙，潜在地改变河流的形态动力学和水生生态系统。先前的工作提出了FSI的概念模型，其中FSI发生的深度有限，是与渗透性沉积物相比床状沉积物相对粒径的函数，并且受到精细沉积物供应和局部流动动力学的影响。我们的研究将这一概念模型应用于一条游荡的中型砾石河床的复杂河段，以研究FSI的时空控制。为了限制FSI的时间，我们使用上游大坝拆除和补充田间方法（散装采样，冻结岩心和渗透袋）释放受污染的沉积物来捕获各种沉积环境中的沉积物。我们的结果表明，即使在形态复杂的范围内，床中的细沉积物含量在沉积设置之间或床表面垂直下方也不会发生显着变化。我们还发现，通过大坝拆除而释放到研究河流中的污染最严重的细沉积物并不存在于床层材料中，在释放污染的沉积物和取样之间的这段时间内，底物可能已被重新加工。我们的观察结果还表明，以前与FSI相关联的导致深空孔隙空间的细小沉积物封闭在我们的田间地区并不明显。这表明在自然系统中，大量的泥沙供应和流动床可能会限制海豹的形成和持久性。

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