scholarly journals A Prototype System for Time-Lapse Electrical Resistivity Tomographies

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Raffaele Luongo ◽  
Angela Perrone ◽  
Sabatino Piscitelli ◽  
Vincenzo Lapenna
Keyword(s):  
Electrical Resistivity ◽  
Time Lapse ◽  
Test Site ◽  
Rain Gauge ◽  
Time Domain Reflectometry ◽  
Acquisition Time ◽  
Time Interval ◽  
Prototype System ◽  
Resistivity Tomography ◽  
Rainwater Infiltration

A prototype system for time-lapse acquisition of 2D electrical resistivity tomography (ERT) and time domain reflectometry (TDR) measurements was installed in a test site affected by a landslide in Basilicata region (southern Italy). The aim of the system is to monitor in real-time the rainwater infiltration into the soil and obtain information about the variation of the water content in the first layers of the subsoil and the possible influence of this variation on landslide activity. A rain gauge placed in the test site gives information on the rainfall intensity and frequency and suggests the acquisition time interval. The installed system and the preliminary results are presented in this paper.

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.

Permafrost Mapping with Electrical Resistivity Tomography: A Case Study in Two Wetland Systems in Interior Alaska

2020 ◽  
Vol 25 (2) ◽  
pp. 199-209
Author(s):  
Christopher H. Conaway ◽  
Cordell D. Johnson ◽  
Thomas D. Lorenson ◽  
Merritt Turetsky ◽  
Eugénie Euskirchen ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Water Content ◽  
Electrical Resistivity Tomography ◽  
Time Lapse ◽  
Research Area ◽  
Acquisition Time ◽  
Unfrozen Water ◽  
Resistivity Tomography ◽  
Interior Alaska ◽  
Unfrozen Water Content

Surface-based 2D electrical resistivity tomography (ERT) surveys were used to characterize permafrost distribution at wetland sites on the alluvial plain north of the Tanana River, 20 km southwest of Fairbanks, Alaska, in June and September 2014. The sites were part of an ecologically-sensitive research area characterizing biogeochemical response of this region to warming and permafrost thaw, and the site contained landscape features characteristic of interior Alaska, including thermokarst bog, forested permafrost plateau, and a rich fen. The results show how vegetation reflects shallow (0–10 m depth) permafrost distribution. Additionally, we saw shallow (0–3 m depth) low resistivity areas in forested permafrost plateau potentially indicating the presence of increased unfrozen water content as a precursor to ground instability and thaw. Time-lapse study from June to September suggested a depth of seasonal influence extending several meters below the active layer, potentially as a result of changes in unfrozen water content. A comparison of several electrode geometries (dipole-dipole, extended dipole-dipole, Wenner-Schlumberger) showed that for depths of interest to our study (0–10 m) results were similar, but data acquisition time with dipole-dipole was the shortest, making it our preferred geometry. The results show the utility of ERT surveys to characterize permafrost distribution at these sites, and how vegetation reflects shallow permafrost distribution. These results are valuable information for ecologically sensitive areas where ground-truthing can cause excessive disturbance. ERT data can be used to characterize the exact subsurface geometry of permafrost such that over time an understanding of changing permafrost conditions can be made in great detail. Characterizing the depth of thaw and thermal influence from the surface in these areas also provides important information as an indication of the depth to which carbon storage and microbially-mediated carbon processing may be affected.

Monitoring the hydrologic behaviour of a mountain slope via time‐lapse electrical resistivity tomography

2009 ◽  
Vol 7 (5-6) ◽  
pp. 475-486 ◽  
Author(s):  
G. Cassiani ◽  
A. Godio ◽  
S. Stocco ◽  
A. Villa ◽  
R. Deiana ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Time Lapse ◽  
Mountain Slope ◽  
Resistivity Tomography

scholarly journals Time-lapse cross-hole electrical resistivity tomography (CHERT) for monitoring seawater intrusion dynamics in a Mediterranean aquifer

2019 ◽  
Author(s):  
Andrea Palacios ◽  
Juan José Ledo ◽  
Niklas Linde ◽  
Linda Luquot ◽  
Fabian Bellmunt ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Seawater Intrusion ◽  
Electrical Resistivity Tomography ◽  
Low Cost ◽  
Heavy Rain ◽  
Time Lapse ◽  
Resistivity Tomography ◽  
Bulk Electrical Conductivity ◽  
Spatial Coverage

Abstract. Surface electrical resistivity tomography (ERT) is a widely used tool to study seawater intrusion (SWI). It is noninvasive and offers a high spatial coverage at a low cost, but it is strongly affected by decreasing resolution with depth. We conjecture that the use of CHERT (cross-hole ERT) can partly overcome these resolution limitations since the electrodes are placed at depth, which implies that the model resolution does not decrease in the zone of interest. The objective of this study is to evaluate the CHERT for imaging the SWI and monitoring its dynamics at the Argentona site, a well-instrumented field site of a coastal alluvial aquifer located 40 km NE of Barcelona. To do so, we installed permanent electrodes around boreholes attached to the PVC pipes to perform time-lapse monitoring of the SWI on a transect perpendicular to the coastline. After two years of monitoring, we observe variability of SWI at different time scales: (1) natural seasonal variations and aquifer salinization that we attribute to long-term drought and (2) short-term fluctuations due to sea storms or flooding in the nearby stream during heavy rain events. The spatial imaging of bulk electrical conductivity allows us to explain non-trivial salinity profiles in open boreholes (step-wise profiles really reflect the presence of fresh water at depth). By comparing CHERT results with traditional in situ measurements such as electrical conductivity of water samples and bulk electrical conductivity from induction logs, we conclude that CHERT is a reliable and cost-effective imaging tool for monitoring SWI dynamics.

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