A modelling study of hyporheic exchange pattern and the sequence, size, and spacing of stream bedforms in mountain stream networks, Oregon, USA
A modelling study of hyporheic exchange pattern and the sequence, size, and spacing of stream bedforms in mountain stream networks, Oregon, USA
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美国俄勒冈州山间溪流网络中的次流交换模式以及河床形态的序列、大小和间距的建模研究
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发表时间：
2006
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通讯作者：
R. Haggerty
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作者：
M. Gooseff;Justin K. Anderson;S. Wondzell;J. Lanier;R. Haggerty
潜流交换流的研究已经确定了控制交换流在通道单位尺度上的物理特征，即产生地下水头分布的河流纵剖面上的坡折。我们最近完成的一项实地研究表明，河流纵向剖面上的河道单位间距可以用来预测山溪床中上升流（潜流进入溪流的流量）和下升流（流入潜流区域的流量）区域之间的间距。在这里，我们使用二维地下水流动和粒子跟踪模型来模拟沿二、三、四阶山溪河道的纵轴垂直和纵向隐流交换。建模使我们能够(1)直观地表示纵剖面的形状对河床下水流网的影响；(2)将河道单元序列和河道间距作为控制潜流带渗透深度和上升流带和下升流带长度的单独因素；(3)评价河床大小和序列的规则模式被实际河流的不规则性所掩盖的程度。我们在两组理想河段和一组观测河段中模拟了潜交换。利用河道形态与流域面积的回归方程构建了理想剖面。通道单元的大小和长度（步长、池长等）随着流顺序的增加而增加。潜流交换流模拟结果表明，随着二级流阶的增加，上升流长度从2.7 m增加到7.6 m，下升流长度从2.9 m增加到6.0 m。随着河流规模从二级增大到四级，理想河段的台阶间距从5.3 m增大到13.7 m。在POOL-STEP-RIFFLE通道单元序列中，二阶流的模拟下水管长度从4.3 m增加到9.7 m，在POOL-STEP-RIFFLE通道单元序列中，从二到四阶流的模拟下水管长度从2.5 m增加到6.1 m。在这些理想通道中，上升流长度随流序的增加而增加。我们的研究结果表明，通道单元间距、大小和顺序对决定上升流和下升流的潜流交换模式都很重要。尽管河床大小和间距的不规则性导致调查河段的流网比理想河段复杂得多，但在调查河段和理想河段中，平均地貌波长与平均隐波波长之间的关系出现了类似的趋势。本文取代了先前发表的版本(水文过程，19(17),2915-2929 (2005))[DOI:10.1002/hyp.5790]。另见撤稿通知DOI:10.1002/hyp.6350版权所有©2006约翰威利父子有限公司
Studies of hyporheic exchange flows have identified physical features of channels that control exchange flow at the channel unit scale, namely slope breaks in the longitudinal profile of streams that generate subsurface head distributions. We recently completed a field study that suggested channel unit spacing in stream longitudinal profiles can be used to predict the spacing between zones of upwelling (flux of hyporheic water into the stream) and downwelling (flux of stream water into the hyporheic zone) in the beds of mountain streams. Here, we use two‐dimensional groundwater flow and particle tracking models to simulate vertical and longitudinal hyporheic exchange along the longitudinal axis of stream flow in second‐, third‐, and fourth‐order mountain stream reaches. Modelling allowed us to (1) represent visually the effect that the shape of the longitudinal profile has on the flow net beneath streambeds; (2) isolate channel unit sequence and spacing as individual factors controlling the depth that stream water penetrates the hyporheic zone and the length of upwelling and downwelling zones; (3) evaluate the degree to which the effects of regular patterns in bedform size and sequence are masked by irregularities in real streams. We simulated hyporheic exchange in two sets of idealized stream reaches and one set of observed stream reaches. Idealized profiles were constructed using regression equations relating channel form to basin area. The size and length of channel units (step size, pool length, etc.) increased with increasing stream order. Simulations of hyporheic exchange flows in these reaches suggested that upwelling lengths increased (from 2·7 m to 7·6 m), and downwelling lengths increased (from 2·9 m to 6·0 m) with increase in stream order from second to fourth order. Step spacing in the idealized reaches increased from 5·3 m to 13·7 m as stream size increased from second to fourth order. Simulated downwelling lengths increased from 4·3 m in second‐order streams to 9·7 m in fourth‐order streams with a POOL–RIFFLE–STEP channel unit sequence, and increased from 2·5 m to 6·1 m from second‐ to fourth‐order streams with a POOL–STEP–RIFFLE channel unit sequence. Upwelling lengths also increased with stream order in these idealized channels. Our results suggest that channel unit spacing, size, and sequence are all important in determining hyporheic exchange patterns of upwelling and downwelling. Though irregularities in the size and spacing of bedforms caused flow nets to be much more complex in surveyed stream reaches than in idealized stream reaches, similar trends emerged relating the average geomorphic wavelength to the average hyporheic wavelength in both surveyed and idealized reaches. This article replaces a previously published version (Hydrological Processes, 19(17), 2915–2929 (2005) [DOI:10.1002/hyp.5790]. See also retraction notice DOI:10.1002/hyp.6350 Copyright © 2006 John Wiley & Sons, Ltd.