ABSTRACT A major problem for the freshwater supply of coastal regions is the intrusion of saltwater into aquifers. Due to extensive extraction of freshwater to suffice increasing drinking water demands and/or in periods of reduced groundwater recharge, the equilibrium state may be disturbed. The result is an upconing or movement of the fresh–saline groundwater interface, which reduces the local drinking water resources at coastal regions or islands. The saltwater monitoring system (SAMOS) is a vertical electrode chain installed in a backfilled borehole. It provides a solution to observe the transition zone in detail, both temporally and spatially. We present monitoring data of the first year from three locations ‐ with different geological conditions that show disturbances in the resistivity distribution that result from the drilling processes. A clayey backfilling, for example, can lead to beam‐like artefacts, and a mixed fluid within the backfilling changes its bulk resistivity, both leading to misinterpretations. We performed data inversion under cylindrically symmetrical conditions in full‐space in order to separate these resistivity artefacts from the undisturbed background. Data inversion reveals that it is possible to separate drilling effects on the resistivity distribution from the undisturbed background. Thus, an interpretation of the natural transition zones can be made immediately after the installation.

中文翻译：

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使用 SAMOS 监测淡水-咸水界面——安装对数据和反演的影响

摘要 沿海地区淡水供应的一个主要问题是海水侵入含水层。由于大量抽取淡水以满足不断增加的饮用水需求和/或在地下水补给减少的时期，平衡状态可能会受到干扰。结果是淡水-咸水地下水界面的上升或移动，这减少了沿海地区或岛屿的当地饮用水资源。盐水监测系统 (SAMOS) 是安装在回填钻孔中的垂直电极链。它提供了一种在时间和空间上详细观察过渡区的解决方案。我们提供了三个地点第一年的监测数据 - 具有不同的地质条件，显示出钻井过程导致电阻率分布的扰动。例如，粘土回填可能导致梁状伪影，回填中的混合流体会改变其体电阻率，两者都会导致误解。我们在全空间的圆柱对称条件下进行了数据反演，以便将这些电阻率伪影与未受干扰的背景分开。数据反演表明，可以将钻孔对电阻率分布的影响与未受干扰的背景区分开来。因此，可以在安装后立即对自然过渡区进行解释。我们在全空间的圆柱对称条件下进行了数据反演，以便将这些电阻率伪影与未受干扰的背景分开。数据反演表明，可以将钻孔对电阻率分布的影响与未受干扰的背景区分开来。因此，可以在安装后立即对自然过渡区进行解释。我们在全空间的圆柱对称条件下进行了数据反演，以便将这些电阻率伪影与未受干扰的背景分开。数据反演表明，可以将钻孔对电阻率分布的影响与未受干扰的背景区分开来。因此，可以在安装后立即对自然过渡区进行解释。