Transient storage and downstream solute transport in nested stream reaches affected by beaver dams
Transient storage and downstream solute transport in nested stream reaches affected by beaver dams
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受河狸坝影响的嵌套溪流中的瞬时储存和下游溶质运输
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
M. Otz
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文献类型：
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作者：
Li Jin;D. Siegel;L. Lautz;M. Otz
临时蓄水是流域水文循环的一个关键因素。通道内缓慢移动的水（死区）和潜流区都可能有助于瞬时储存，从而保留水和溶质，增加停留时间并影响流中的溶质传输。海狸坝和其他流中障碍物在整个低阶流衰减径流，并提供死区存储池。在这篇文章中，我们报告了在Cherry Creek（怀俄明州，美国）的嵌套流段中进行的四个示踪剂试验的结果，覆盖了12.5 km的流长，以探索比弗坝的障碍程度及其蓄水如何影响美国西部落基山脉地区低阶流中的水瞬时储存和下游溶质运移。示踪剂试验的旅行时间参数随比弗坝数量（N）和池塘大小（V）线性增加。峰值浓度的传播时间（Tp）、染料云的前缘（Tl）和后缘（Tt）以及染料云的持续时间（Td）与N和V的线性回归都是显著的（R2 = 0.99）。Tt与N和V的线性回归的斜率比T1的斜率大三倍，这表明可能部分由流系统中的瞬时储存引起较长的停留时间。一维入流和储存输运（奥蒂斯）模拟了瞬时储存区的横截面积（As）和弥散系数（D）随N和V以及河段长度线性增加。两个瞬态存储度量，F平均值和$F_{
m {med}}^{200}$也显示出随N和V的普遍增加，尽管这种关系没有那么强。这表明与海狸坝相关的河道死区为产生瞬时蓄水提供了机会。扩散系数与河段长度呈线性关系，表明扩散过程可能类似于地下水环境中的水动力扩散。版权所有© 2009约翰威利父子有限公司。
Transient storage constitutes a key element in the hydrologic cycle of watersheds. Both in‐channel slow moving water (dead zones) and hyporheic zones can contribute to transient storage, which retains water and solutes, increases residence time and influences solute transport in streams. Beaver dams and other in‐stream obstructions throughout low‐order streams attenuate streamflow and provide dead zone storage in pools. In this article, we report the results of four tracer tests in nested stream reaches in Cherry Creek (Wyoming, USA) covering ∼2·5 km of stream length to explore how the degree of beaver dam obstructions and their impoundments influence water transient storage and downstream solute transport in low‐order streams in the Rocky Mountain region of the American West. Travel‐time parameters for the tracer tests increased linearly with beaver dam number (N) and pond size (V). Linear regression of the travel time to the peak concentration (Tp), the leading (Tl) and tailing edge (Tt) of the dye cloud and the duration of the dye cloud (Td) versus N and V were all significant (R2 = 0·99). Slopes of the linear regressions of Tt versus N and V, were three times larger than those for Tl, suggesting that longer residence times may be caused, in part, by transient storage in the stream system. One‐dimensional transport with inflow and storage (OTIS) modelled cross‐sectional area of transient storage zone (As) and dispersion coefficients (D) increased linearly with N and V and reach length. Two transient storage metrics, Fmean and $F_{
m {med}}^{200}$, also showed a general increase with N and V, although the relationship was not as strong. This suggests that in‐channel dead zones associated with beaver dams provide opportunities for generating transient water storage. The linear relationship between dispersion coefficient and reach length suggests the dispersion process might be analogous to the hydrodynamic dispersion in groundwater settings. Copyright © 2009 John Wiley & Sons, Ltd.