Lateral inflows, stream‐groundwater exchange, and network geometry influence stream water composition
Lateral inflows, stream‐groundwater exchange, and network geometry influence stream water composition
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侧向流入、河流-地下水交换和网络几何形状影响河流水成分
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
T. Covino
中科院分区：
文献类型：
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作者：
J. Mallard;B. McGlynn;T. Covino
河流网络及其与山坡和浅层地下水的水文相互作用在修改和传输流域信号中的作用是一个活跃的研究领域。河流网络可以修改流域信号的主要方式之一是通过空间可变的河流增益和损失，在此描述为水文周转。我们测量水文增益和损失的范围内使用示踪剂实验在整个公牛鳟鱼流域的锯齿山脉的爱达荷州。我们使用（1）流域面积与河流流量之间的经验关系和（2）河流流量与地下水系统的河流水损失百分比之间的经验关系，将河段规模实验的结果扩展到河流网络。因此，我们将（1）山坡和河流网络之间的联系，通过横向流入和（2）河流网络和浅层地下水通过水文交换。我们实现了这些关系在一个简洁的分析框架，以模拟水文周转跨流网络和估计变量的影响上游河段和径流源位置上跨流网络的流水组成。应用到六个自然锯齿流域和七个合成流域不同的地形结构和流网络的几何形状表明，从任何上游来源的贡献取决于初始输入的大小，但也对水文周转发生沿着流网络的分布。由于流域结构和水系几何形态的共同作用，各流域水系沿着水系的水源组成演化具有独特性。我们的研究结果表明，分布式表示的水文周转在流网络规模可以提高理解如何流网络可以修改源水成分沿着流。
The role of stream networks and their hydrologic interaction with hillslopes and shallow groundwater in modifying and transporting watershed signals is an area of active research. One of the primary ways that stream networks can modify watershed signals is through spatially variable stream gains and losses, described herein as hydrologic turnover. We measured hydrologic gain and loss at the reach scale using tracer experiments throughout the Bull Trout watershed in the Sawtooth Mountains of Idaho. We extended the results of reach scale experiments to the stream network using empirical relationships between (1) watershed area and stream discharge and (2) stream discharge and percent stream water loss to the groundwater system. We thus incorporate linkages between (1) hillslopes and stream networks via lateral inflows and (2) stream networks and shallow groundwater via hydrologic exchange. We implemented these relationships within a concise analytical framework to simulate hydrologic turnover across stream networks and estimate the variable influence exerted by upstream reaches and streamflow source locations on stream water composition across stream networks. Application to six natural Sawtooth watersheds and seven synthetic watersheds with varying topographic structure and stream network geometry indicated that contributions to discharge from any upstream source depend on the magnitude of the initial input, but also on the distribution of hydrologic turnover occurring along the stream network. The evolution of stream water source compositions along stream networks was unique in each watershed due to the combination of watershed structure and stream network geometry. Our results suggest that a distributed representation of hydrologic turnover at the stream network scale can improve understanding of how the stream network can modify source water compositions along the stream.