Observing lingering hyporheic storage using electrical resistivity: variations around stream restoration structures, Crabby Creek, PA
Observing lingering hyporheic storage using electrical resistivity: variations around stream restoration structures, Crabby Creek, PA
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使用电阻率观察挥之不去的潜流储存：河流恢复结构周围的变化，宾夕法尼亚州克拉比溪
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发表时间：
2013
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通讯作者：
D. Rosenberry
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作者：
L. Toran;J. Nyquist;Allison C. Fang;R. Ryan;D. Rosenberry
延时地球物理测量可以通过检测对盐水示踪剂的反应变化来绘制挥之不去的地下蓄积物地图。示踪剂测试在费城郊外的城市溪流Crabby Creek进行，以检查溪流恢复结构和不同沉积物厚度的影响。我们比较了两个13.5米长的地区的电阻率测量和大范围的井采样(57口井)，每一口井都有一个由J型钩产生的阶跃下降。根据测井数据和地球物理数据，这两个台阶滴在示踪剂行为上有所不同。测井资料表明，到达时间变化较大的地方，河床泥沙较厚，而较均匀的地方，泥沙较薄。薄沉积河段的电阻率在J型钩上下游的潜流带中显示出挥之不去的示踪剂。在沉积物较厚的第二个河段，低渗带中挥之不去的示踪剂在J形钩下游更广泛。两种方法对两个河段的对比结果表明，沉积物对潮汐交换的影响比该位置的阶跃更大。在这两个段中，电阻率反演与井数据的不同之处在于，它显示了井样本返回背景后的示踪剂证据，绘制了台阶上游或下游的挥之不去的示踪剂。我们的结论是，电阻率测量可能成为描述潜流带特征的重要工具，因为它们提供了有关潜流带中缓慢运动的流体程度的信息，这些流体具有增强化学反应的潜力。版权所有©2012 John Wiley&Sons，Ltd.
Time‐lapse geophysical surveys can map lingering hyporheic storage by detecting changes in response to saline tracer. Tracer tests were conducted in Crabby Creek, an urban stream outside Philadelphia, to examine the influence of stream restoration structures and variable sediment thickness. We compared electrical resistivity surveys with extensive well sampling (57 wells) in two 13.5‐m‐long reaches, each with a step drop created by a J‐hook. The two step drops varied in tracer behaviour, based on both the well data and the geophysical data. The well data showed more variation in arrival time where the streambed sediment was thick and was more uniform where sediment was thin. The resistivity in the reach with thin sediment showed lingering tracer in the hyporheic zone both upstream and downstream from the J‐hook. In the second reach where the sediment was thicker, the lingering tracer in the hyporheic zone was more extensive downstream from the J‐hook. The contrasting results between the two reaches from both methods suggested that sediments influenced hyporheic exchange more than the step at this location. Resistivity inversion differed from well data in both reaches in that it showed evidence for tracer after well samples had returned to background, mapping lingering tracer either upstream or downstream of a step. We conclude that resistivity surveys may become an important tool for hyporheic zone characterization because they provide information on the extent of slow moving fluids in the hyporheic zone, which have the potential to enhance chemical reactions. Copyright © 2012 John Wiley & Sons, Ltd.