Characterization of water content dynamics and tracer breakthrough by 3-D electrical resistivity tomography (ERT) under transient unsaturated conditions

2015 ◽  
Vol 51 (1) ◽  
pp. 97-124 ◽  
Author(s):  
Markus Wehrer ◽  
Lee D. Slater
Keyword(s):  
Electrical Resistivity ◽  
Water Content ◽  
Electrical Resistivity Tomography ◽  
Resistivity Tomography

Characterization Of Complex Archaeological Sites Using 3D Electrical Resistivity Tomography

2004 ◽  
Author(s):  
Annalisa Morelli ◽  
Gianfranco Morelli ◽  
Paolo Chiara ◽  
Alessio Pacchini ◽  
Federico Fischanger
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Archaeological Sites ◽  
Resistivity Tomography

scholarly journals Study of Seasonal Rainfall Infiltration via Time-Lapse Surface Electrical Resistivity Tomography: Case Study of Gamboa Area, Panama Canal Watershed

2013 ◽  
Vol 6 ◽  
pp. ASWR.S12306 ◽  
Author(s):  
Alexis Mojica ◽  
Irving Díaz ◽  
Carlos A. Ho ◽  
Fred Ogden ◽  
Reinhardt Pinzón ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Water Content ◽  
Electrical Resistivity Tomography ◽  
Time Lapse ◽  
Panama Canal ◽  
Resistivity Tomography ◽  
Rainwater Infiltration ◽  
Strong Inversion ◽  
Percent Difference

The present investigation was focused on the variations in rainwater infiltration experienced by soils of Gamboa zone (Panama Canal Watershed) during various seasons of the year, employing a time-lapse analysis of electrical resistivity tomography (ERT). In 2009, a total of 3 geoelectrical tests were undertaken during the dry, transition and rainy seasons across a profile 47 m in length, strategically distributed on site. The results obtained in this study showed strong variations in calculated resistivity between these seasons, taking the dry season as a reference with decreases and increases of percent difference of resistivity between -20% and -100%, and between 50% and 100%, respectively. These decreases, when displayed through a sequence of time-lapse images, reveal a superficial extension of the water content variations along the entire profile, as well as strong inversion artifacts showing false increases of calculated electrical resistivity. Decreases are the product of the rainfall increase obtained in this type of tropical environment; permanent conductive anomalies in 3 tests are associated with the streams close to the study site. The results of this work were compared with a simulation resulting from a series of bidimensional models applied to the 3 studies evaluated: dry, transition and rainy seasons.

scholarly journals Exploring the regolith with electrical resistivity tomography in largescale surveys: electrode spacing related issues and possibility

2020 ◽  
Author(s):  
Laurent Gourdol ◽  
Rémi Clément ◽  
Jérôme Juilleret ◽  
Laurent Pfister ◽  
Christophe Hissler
Keyword(s):  
Electrical Resistivity ◽  
Apparent Resistivity ◽  
Large Scale ◽  
Electrical Resistivity Tomography ◽  
Subsurface Layer ◽  
Electrode Spacing ◽  
High Resistivity ◽  
Constant Thickness ◽  
Resistivity Tomography

Abstract. Within the Critical Zone, regolith plays a key role in the fundamental hydrological functions of water collection, storage, mixing and release. Electrical Resistivity Tomography (ERT) is recognized as a remarkable tool for characterizing the geometry and properties of the regolith, overcoming limitations inherent to conventional borehole-based investigations. For exploring shallow layers, a small electrode spacing (ES) will provide a denser set of apparent resistivity measurements of the subsurface. As this option is cumbersome and time-consuming, smaller ES – albeit offering poorer shallow apparent resistivity data – are often preferred for large horizontal ERT surveys. To investigate the negative trade-off between larger ES and reduced accuracy of the inverted ERT images for shallow layers, we use a set of synthetic conductive/resistive/conductive three-layered soil–saprock/saprolite–bedrock models in combination with a reference field dataset. Our results suggest that an increase in ES causes a deterioration of the accuracy of the inverted ERT images in terms of both resistivity distribution and interface delineation and, most importantly, that this degradation increases sharply when the ES exceeds the thickness of the top subsurface layer. This finding, which is obvious for the characterization of shallow layers, is also relevant even when solely aiming for the characterization of deeper layers. We show that an oversized ES leads to overestimations of depth to bedrock and that this overestimation is even more important for subsurface structures with high resistivity contrast. To overcome this limitation, we propose adding interpolated levels of surficial apparent resistivity relying on a limited number of ERT profiles with a smaller ES. We demonstrate that our protocol significantly improves the accuracy of ERT profiles when using large ES, provided that the top layer has a rather constant thickness and resistivity. For the specific case of large-scale ERT surveys the proposed upgrading procedure is cost-effective in comparison to protocols based on small ES.

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