Resolving centimeter‐scale flows in aquifers and their hydrostratigraphic controls

The rate of groundwater flow has long been recognized as a critical control on solute transport in the subsurface. However, information about groundwater flux and its variability in space is rarely available, especially at the resolution required for investigations at sites of groundwater contamination. Recently, high‐resolution information about vertical variations in groundwater flux was obtained using fiber‐optic distributed temperature sensing technology to monitor the temperature response to active heating in a well. A series of vertical thermal profiles were acquired at a 1.4 cm resolution in a sand and gravel aquifer. These high‐resolution profiles, which display many of the same general features as hydraulic conductivity (K) profiles obtained using multiple techniques at the same well, provide new insights into site hydrostratigraphy. In particular, the near‐continuous profiles reveal the existence of thin zones of relatively high or low velocity that would be difficult to detect using other methods. These profiles also demonstrate that vertical variations in K may not be an accurate indicator of vertical variability in groundwater flux in highly heterogeneous aquifers.

Raw project data is available by contacting [e-mail]

地下水流动速率长期以来被视为控制地下水中溶质运输的关键因素。然而，关于地下水通量和其在空间上的变化的信息往往难以获取，尤其是在地下水污染调查所需的高分辨率水平。近期，利用光纤分布式温度传感技术获取了关于地下水通量垂直变化的高分辨率信息，以监测井中主动加热的温度响应。在沙砾含水层中，以1.4厘米的分辨率获得了一系列垂直热剖面。这些高分辨率剖面与在同一井中使用多种技术获得的水力传导率（K）剖面具有许多相同的一般特征，为该地点的水文地层学研究提供了新的见解。特别是，近乎连续的剖面揭示了相对高或低速度的薄层区域的存在，这些区域使用其他方法难以检测。此外，这些剖面还表明，在高度异质的含水层中，K的垂直变化可能不是垂直地下水通量变化的准确指标。

原始项目数据可通过联系 [e-mail] 获取。