Impact of Dynamically Changing Discharge on Hyporheic Exchange Processes Under Gaining and Losing Groundwater Conditions
Impact of Dynamically Changing Discharge on Hyporheic Exchange Processes Under Gaining and Losing Groundwater Conditions
复制标题
地下水获取和流失条件下动态变化流量对潜流交换过程的影响
DOI：
--
复制
发表时间：
2018
影响因子：
5.4
通讯作者：
J. Lewandowski
中科院分区：
文献类型：
--
作者：
Liwen Wu;Tanu Singh;J. Gomez‐Velez;G. Nützmann;A. Wörman;S. Krause;J. Lewandowski
河道流量、地貌环境和区域地下水流决定了底形引起的潜流交换的时空变化以及它所驱动的地球化学热点和热点时刻的出现。特别感兴趣的是，显着不足的研究，是动态变化的流量的作用，在潜流交换过程中，以及如何区域地下水流调制的瞬态效应。在这项研究中，我们使用一个简化的复杂性模型，系统地探讨了在不同床形几何形状的系统中，床形诱导的潜流对动态变化的排放事件的响应，这些系统暴露于不同程度的地下水流（在上升流和下降流条件下）。考虑到这一点，我们定义的指标，以量化的影响的瞬态：空间范围的潜流区，净潜流通量，平均停留时间，和反硝化效率。我们发现，区域地下水流和地貌环境极大地调节了由单峰排放事件驱动的底形诱导的潜流响应的时间演化。瞬变的影响减少增加地下水上升流或下降流通量，降低床形长宽比，降低通道坡度。此外，我们注意到，增加排放强度可以减少区域地下水流对瞬变效应的调制作用，但很难克服地貌控制。这些研究结果强调了在一个更全面的框架内评估潜流交换过程的必要性。
Channel discharge, geomorphological setting, and regional groundwater flow determine the spatiotemporal variability of bedform‐induced hyporheic exchange and the emergence of biogeochemical hot spots and hot moments that it drives. Of particular interest, and significantly understudied, is the role that dynamically changing discharge has on the hyporheic exchange process and how regional groundwater flow modulates the effects of transience. In this study, we use a reduced‐complexity model to systematically explore the bedform‐induced hyporheic responses to dynamically changing discharge events in systems with different bedform geometries exposed to varying degrees of groundwater flow (under both upwelling and downwelling conditions). With this in mind, we define metrics to quantify the effects of transience: spatial extent of the hyporheic zone, net hyporheic flux, mean residence time, and denitrification efficiency. We find that regional groundwater flow and geomorphological settings greatly modulate the temporal evolution of bedform‐induced hyporheic responses driven by a single‐peak discharge event. Effects of transience diminish with increasing groundwater upwelling or downwelling fluxes, decreasing bedform aspect ratios, and decreasing channel slopes. Additionally, we notice that increasing discharge intensities can reduce the modulating impacts of regional groundwater flow on the effects of transience but hardly overcomes the geomorphological controls. These findings highlight the necessities of evaluating hyporheic exchange processes in a more comprehensive framework.
影响因子：
3.7
作者：
Krause, Stefan;Tecklenburg, Christina;Naden, Emma
通讯作者：
Naden, Emma