Quantifying streambed advection and conduction heat fluxes
Quantifying streambed advection and conduction heat fluxes
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DOI：
10.1002/2016wr019813
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发表时间：
2017-02-01
影响因子：
5.4
通讯作者：
Luce, Charles H.
中科院分区：
文献类型：
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作者：
Caissie, Daniel;Luce, Charles H.
地下水和伴随的热通量与水生生境特别相关，因为它们影响河流和河床内的生活条件。这项研究的重点是理论和发展新的方程，以估计传导和平流热通量进出床，纠正了一些早期的误解，并增加了参数，扩大了我们对热通量的时间的理解。利用加拿大新不伦瑞克双体船的流/床温度资料对新的热通量方程进行了说明。结果表明，当表层水温(1)服从正弦函数叠加在稳态条件(恒定的深层河床温度)上时，通量之间存在重要关系；(2)当两个频率(年和日)的水温正弦变化叠加时，通量之间存在着重要的关系。当流动温度作为规定的边界条件时，床面流体通量对流动温度的贡献是通过传导温度梯度的影响而发生的，而不是通过冷水/温水的直接贡献/混合。然而，可以修改边界条件，以考虑冷水/暖水的直接贡献(例如，局部上升流)和对传导热流的影响。所建立的方程可以预测夏季由河流水的Diel和年温度波动驱动的向床的传导通量，并且在解析解和现场数据之间观察到很好的一致性。这项研究的结果提供了对地下水和热通量的更好的了解，这最终将导致更好的溪流温度模型和更好的渔业资源管理。
Groundwater and accompanying heat fluxes are particularly relevant for aquatic habitats as they influence living conditions both within the river and streambed. This study focuses on the theory and the development of new equations to estimate conduction and advection heat fluxes into and out of the bed, correcting some earlier misunderstandings and adding parameterizations that extend our understanding of timing of heat fluxes. The new heat flux equations are illustrated using Catamaran Brook (New Brunswick, Canada) stream/streambed temperature data. We show important relationships between fluxes when the surface water temperature (1) follows a sinusoidal function superimposed on a steady state condition (constant deep streambed temperature) and (2) when sinusoidal variations in stream temperature at two frequencies (annual and diel) are superimposed. When the stream temperature is used as a prescribed boundary condition, the contribution of bed fluid fluxes to stream temperature occurs through the effects of conductive thermal gradients, not through direct contribution/mixing of cold/warm water. Boundary conditions can be modified, however, to account for direct contribution of cold/warm water (e.g., localized upwelling) and consequences for the conduction heat flux. Equations developed allow for prediction of conductive fluxes to the bed during summer driven by diel and annual temperature fluctuations of the stream water and good agreement was observed between analytic solutions and field data. Results from this study provide a better insight into groundwater and heat fluxes which will ultimately result in better stream temperature models and a better management of fisheries resources.