Transient electromagnetic sounding for groundwater

Fitterman, David V.; Stewart, Mark T.

doi:10.1190/1.1442158

Cited by 375 publications

(172 citation statements)

References 13 publications

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“…Because the induced current is controlled by the resistivity structure of the material beneath the loop, the secondary magnetic field produced by this current system can be measured to determine the geoelectrical section [10] and [11].…”

Section: Tem Sounding Methodsmentioning

confidence: 99%

Relevance of AEM and TEM to Detect the Groundwater Aquifer at Faiyum Oasis Area, Faiyum, Egypt

Basheer¹,

Taha²,

El-Kotb³

et al. 2014

IJG

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This study investigates the groundwater aquifer located in Fayuim oasis. In this study, two of the electromagnetic measurement methods have been used in determining the hydrological situation in the Fayoum oasis. The first is airborne electromagnetic (AEM) which, sometimes is referred to as Helicopter electromagnetic (HEM) and the second is ground Time-domain Electromagnetic method (TEM). The subsurface consists of four geoelectrical layers with a rough slope towards the center. The third and the fourth layers in the succession are suggested to be the two-groundwater aquifers. The third layer saturates with fresh water overlying saline water which exists in the bottom of the second one. It is worth mentioning that the depth of the fresh water surface undulates between the surface level in two lakes in the study area and 57 meters below the ground, whereas the thickness of the fresh water aquifer varies from 13 to 36 meters. The depth of the saline water surface undulates between 59 and 81 meters below the ground. In general, airborne electromagnetic surveying has the advantage of fast resistivity mapping with high lateral resolution. Groundbased geophysical surveys are often more accurate, but they are definitely slower than airborne surveys. It depends on targets of interest, time, budget, and manpower available by the method or the combination of methods that will be chosen. A combination of different methods is useful to obtain a detailed understanding of the subsurface resistivity distribution.

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Section: Tem Sounding Methodsmentioning

confidence: 99%

Relevance of AEM and TEM to Detect the Groundwater Aquifer at Faiyum Oasis Area, Faiyum, Egypt

Basheer¹,

Taha²,

El-Kotb³

et al. 2014

IJG

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“…The TEM method was originally developed for use in mineral exploration (Kaufman and Keller, 1983;McNeill, 1990), but over the past 25 years its use has expanded to groundwater and environmental investigations (Fitterman and Stewart, 1986;Fitterman, 1989;Goldman and others, 1991;Fitterman and others, 1999;Fitterman and Labson, 2005).…”

Section: Description Of Transient Electromagnetic Soundingmentioning

confidence: 99%

Transient electromagnetic soundings in the San Luis Valley, Colorado, near the Great Sand Dunes National Park and Preserve and the Alamosa National Wildlife Refuge (field seasons 2007, 2009, and 2011)

Fitterman¹

2017

Data Series

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For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit https://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Electrical conductivity (σ) can be converted to electrical resistivity (ρ) in ohm-meters (ohm-m) as follows. Conversion Factors Electrical conductivity (σ) units Supplemental InformationSpecific conductance (SC) refers to fluid electrical conductivity corrected to a temperature of 25 °C. The units of specific conductance are usually in microsiemens per centimeter (μS/cm). The above conversions apply. DatumHorizontal coordinate information is referenced to the North American Datum of 1927 (NAD27).Elevation information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29). Abbreviations AbstractTransient electromagnetic (TEM) soundings were made in the San Luis Valley, Colorado, to map the location of a blue clay unit as well as to investigate the presence of suspected faults. A total of 147 soundings were made near and in Great Sand Dunes National Park and Preserve, and an additional 6 soundings were made near Hansen Bluff on the eastern edge of the Alamosa National Wildlife Refuge. The blue clay is a significant hydrologic feature in the area that separates an unconfined surface aquifer from a deeper confined aquifer. Knowledge of its location is important to regional hydrological models. Previous analysis of well logs has shown that the blue clay has a resistivity of 10 ohm-meters or less, which is in contrast to the higher resistivity of sand, gravel, and other clay units found in the area, making it a very good target for TEM soundings. The top of the blue clay was found to have considerable relief, suggesting the possibility of deformation of the clay during or after deposition. Because of rift activity, deformation is to be expected. Of the TEM profiles made across faults identified by aeromagnetic data, some showed resistivity variations and (or) subsurface elevation relief of resistivity units, suggestive of faulting. Such patterns were not associated with all suspected faults. The Hansen Bluff profile showed variations in resistivity and depth to conductor that coincide with a scarp between the highlands to the east and the floodplain of the Rio Grande to the west.

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“…The TEM method has the advantage as it can investigate hundreds of meters in depth with great capability of detecting conductive layers. According to the results of many researchers worldwide, the geoelectrical stratigraphy given by TEM models usually has a good correlation with geological information, which makes it a good method for mapping subsurface conductive zones [1] [2]. For this reason, the TEM method is being used for water table mapping at great depths, representing a reliable alternative to vertical electrical soundings (VES) that may require long aperture ranges depending on the investigation depth.…”

Section: Introductionmentioning

confidence: 99%

2D TEM Modeling for a Hydrogeological Study in the Paraná Sedimentary Basin, Brazil

Almeida¹,

Porsani²,

Santos³

et al. 2017

IJG

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This work uses 2D TEM (Transient Electromagnetic) modeling for a hydrogeological study in the Paraná sedimentary basin. The study area is located at the northern region of the state of São Paulo, Brazil, where groundwater is exploited from two aquifer systems: one sedimentary, shallow, and the other crystalline, deep. The interest in applying the TEM method in this area owes to the high exploitation rates of groundwater from the crystalline aquifer system for irrigation, which is triggering considerable seismic activity locally. This aquifer system is composed of fractured basalt within the Serra Geral Formation and is about 120 m deep. Eighty-six TEM soundings were acquired at this location, but in nine cases the data did not fit the modelled curve for 1D geoelectrical models due to the geological complexity of the area. This paper shows 2D geoelectrical modeling results based on the FDTD (Finite Differences in Time Domain) method to explain the lateral resistivity variation within the geological setting. A 2D model was generated for each sounding and compared with 1D inversion models as well as with direct information from wells. The results show some vertical variations of about 10 to 30 meters on the upper interface of the basalt layer from Serra Geral Formation. They are located at approximately 60 meters from the center of the soundings. The existence of these 2D structures in the subsurface can be related to the drainage system in the study area. The presence of these structures may indicate a connection between the shallow and deep aquifer systems, acting like a conduit that may contribute to the seismic activity reported.

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Transient electromagnetic sounding for groundwater

Cited by 375 publications

References 13 publications

Relevance of AEM and TEM to Detect the Groundwater Aquifer at Faiyum Oasis Area, Faiyum, Egypt

Relevance of AEM and TEM to Detect the Groundwater Aquifer at Faiyum Oasis Area, Faiyum, Egypt

Transient electromagnetic soundings in the San Luis Valley, Colorado, near the Great Sand Dunes National Park and Preserve and the Alamosa National Wildlife Refuge (field seasons 2007, 2009, and 2011)

2D TEM Modeling for a Hydrogeological Study in the Paraná Sedimentary Basin, Brazil

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Transient electromagnetic sounding for groundwater

Cited by 375 publications

References 13 publications

Relevance of AEM and TEM to Detect the Groundwater Aquifer at Faiyum Oasis Area, Faiyum, Egypt

Relevance of AEM and TEM to Detect the Groundwater Aquifer at Faiyum Oasis Area, Faiyum, Egypt

Transient electromagnetic soundings in the San Luis Valley, Colorado, near the Great Sand Dunes National Park and Preserve and the Alamosa National Wildlife Refuge (field seasons 2007, 2009, and 2011)

2D TEM Modeling for a Hydrogeological Study in the Paran&#225; Sedimentary Basin, Brazil

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Resources

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2D TEM Modeling for a Hydrogeological Study in the Paraná Sedimentary Basin, Brazil