In the past several decades, there has been considerable interest in groundwater-surface water interactions and their ability to regulate and cycle nutrients and pollutants. These interactions are spatially and temporally complex; however, electrical resistivity imaging can be a useful tool for their characterization. Here, an electrical resistivity imaging monitoring array was installed laterally across a groundwater-dominated Chalk river and into the adjacent riparian wetland; data were collected over a period of 1 year. Independent inversions of data from the entire transect were performed to account for the changing river stage and river water conductivity. Additionally, data from just the riparian zone were inverted using a temporally constrained inversion algorithm and the correlation between the riparian zone resistivity patterns and river stage was assessed using time-series analysis. The river stage and the Chalk groundwater level followed similar patterns throughout the year, and both exhibited a sharp drop following cutting of the in-stream vegetation. For the independent inversions, fixing the river resistivity led to artifacts, which prevented reliable interpretation of dynamics in the riverbed. However, the resistivity structure of the riparian zone coincided well with the intrusively derived boundary between the peat and the gravel present at the field site. Time-series analysis of the inverted riparian zone models permitted identification of seven units with distinct hydrological resistivity dynamics (five zones within the peat and two within the gravel). The resistivity patterns in the gravel were predominantly controlled by up-welling of resistive groundwater and the down-welling of more conductive peat waters following the river vegetation cutting event. In comparison, although the vegetation cutting influenced the resistivity dynamics in the peat zones, the resistivity dynamics were also influenced by precipitation events and increasing pore-water conductivity, likely arising from biological processes. It is anticipated that the distinct hydrological units are results of the complex fluvial history of the site. It is evident that such approaches combining electrical resistivity imaging and time-series analysis are useful for understanding the spatial extent and timing of hydrological processes to aid in the better characterization of groundwater-surface water interactions

中文翻译：

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白垩河和邻近河岸带河流-地下水相互作用的电阻率监测

在过去的几十年里，人们对地下水-地表水相互作用及其调节和循环养分和污染物的能力产生了相当大的兴趣。这些相互作用在空间和时间上都很复杂；然而，电阻率成像可以成为表征它们的有用工具。在这里，电阻率成像监测阵列横向安装在地下水占主导地位的乔克河并进入相邻的河岸湿地；数据收集时间为 1 年。对整个断面的数据进行了独立反演，以说明河流水位和河水电导率的变化。此外，使用时间约束反演算法反演仅来自河岸带的数据，并使用时间序列分析评估河岸带电阻率模式与河流水位之间的相关性。河流水位和白垩地下水位全年遵循相似的模式，并且在河流中的植被被切割后都表现出急剧下降。对于独立反演，固定河流电阻率会导致伪影，这阻碍了对河床动力学的可靠解释。然而，河岸带的电阻率结构与现场存在的泥炭和砾石之间侵入性导出的边界吻合。倒置河岸带模型的时间序列分析允许识别具有不同水文电阻率动态的七个单元（泥炭中的五个区域和砾石中的两个区域）。砾石中的电阻率模式主要受电阻性地下水的上升控制和河流植被切割事件后更具导电性的泥炭水的下降控制。相比之下，虽然植被切割影响了泥炭带的电阻率动态，但电阻率动态也受到降水事件和孔隙水电导率增加的影响，这可能是由生物过程引起的。预计不同的水文单位是该地点复杂河流历史的结果。