Beaver dam analogues drive heterogeneous groundwater–surface water interactions
Beaver dam analogues drive heterogeneous groundwater–surface water interactions
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海狸坝类似物驱动异质地下水与地表水相互作用
DOI：
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发表时间：
2020
影响因子：
3.2
通讯作者：
Casey Pearce
中科院分区：
文献类型：
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作者：
J. Wade;L. Lautz;C. Kelleher;P. Vidon;Julianne Davis;J. Beltran;Casey Pearce
比弗坝类似物（BDA）是一种具有成本效益的河流恢复方法，利用天然比弗坝对河道稳定性和当地水文的公认环境效益。虽然天然河狸坝是已知的发挥相当大的影响，通过调解地貌过程，营养循环和地下水-地表水的相互作用的河流系统的水文条件，河狸衍生的恢复方法对地下水-地表水交换的影响很差的特点。为了解决这一问题，我们在2019年夏天监测了沿怀俄明州中部河流沿着安装的一系列BDA的潜流交换通量和河床孔隙水地球化学。通过热示踪法和垂直水力梯度对河床通量进行了量化。生物地球化学活动进行了评价，主要离子孔隙水化学和主成分分析。垂直通量约1.0米/天，观察周围的BDA，是硝酸盐生产，地下水上升，厌氧还原的空间异质区的发展。在不同大小的BDA中观察到了潜流区过程的强烈对比。这表明，结构可能具有尺寸依赖性行为，仅在超过阈值水力台阶高度后改变地下水-地表水相互作用。所研究的BDA周围的潜流交换和生物地球化学循环模式类似于天然海狸坝周围的模式，这表明BDA可能在1年的时间内为通道复杂性和近流功能提供相当的益处。
Beaver dam analogues (BDAs) are a cost‐effective stream restoration approach that leverages the recognized environmental benefits of natural beaver dams on channel stability and local hydrology. Although natural beaver dams are known to exert considerable influence on the hydrologic conditions of a stream system by mediating geomorphic processes, nutrient cycling, and groundwater–surface water interactions, the impacts of beaver‐derived restoration methods on groundwater–surface water exchange are poorly characterized. To address this deficit, we monitored hyporheic exchange fluxes and streambed porewater biogeochemistry across a sequence of BDAs installed along a central Wyoming stream during the summer of 2019. Streambed fluxes were quantified by heat tracing methods and vertical hydraulic gradients. Biogeochemical activity was evaluated using major ion porewater chemistry and principal component analysis. Vertical fluxes of approximately 1.0 m/day were observed around the BDAs, as was the development of spatially heterogeneous zones of nitrate production, groundwater upwelling, and anaerobic reduction. Strong contrasts in hyporheic zone processes were observed across BDAs of differing sizes. This suggests that structures may function with size‐dependent behaviour, only altering groundwater–surface water interactions after a threshold hydraulic step height is exceeded. Patterns of hyporheic exchange and biogeochemical cycling around the studied BDAs resemble those around natural beaver dams, suggesting that BDAs may provide comparable benefits to channel complexity and near‐stream function over a 1‐year period.