Shallow geophysical techniques to investigate the groundwater table at the Great Pyramids of Giza, Egypt

Abstract. The near-surface groundwater aquifer that threatened the Great Pyramids of Giza, Egypt, was investigated using integrated geophysical surveys. A total of 10 electrical resistivity imaging, 26 shallow seismic refraction, and 19 ground-penetrating radar surveys were conducted in the Giza Plateau. Collected data for each method were evaluated by state-of-the art processing and modeling techniques. A three-layer model depicts the subsurface layers and better delineates the groundwater aquifer and water table elevation. The resistivity of the aquifer layer and seismic velocity vary between 40 and 80 Ωm and between 1500 and 2500 m s−1, respectively. The average water table elevation is about +15 m, which is safe for the Great Sphinx, but it is still subjected to potential hazards from the Nazlet El-Samman suburb where the water table elevation reaches 17 m. A shallower water table at the Valley Temple and the tomb of Queen Khentkawes, with a low topographic relief, represents severe hazards. It can be concluded that a perched groundwater table is detected in the elevated topography to the west and southwest that might be due to runoff and capillary seepage.

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Geostatistical simulation for geophysical applications—Part II: Geophysical modeling

Geophysics ◽

10.1190/1.1442791 ◽

1990 ◽

Vol 55 (11) ◽

pp. 1441-1446 ◽

Cited By ~ 2

Author(s):

P. N. Shive ◽

T. Lowry ◽

D. H. Easley ◽

L. E. Borgman

Keyword(s):

Physical Properties ◽

Seismic Velocity ◽

Seismic Refraction ◽

Three Dimensional ◽

Companion Paper ◽

Geostatistical Simulation ◽

Near Surface ◽

Geophysical Modeling ◽

Karst Environment ◽

Geophysical Surveys

A companion paper (this issue) describes a method for producing three‐dimensional simulations of physical properties for different geologic situations. Here we create a simulation for a particular case, which is a near‐surface (<80 ft deep) description of a karst environment. We simulate seismic velocity, density, resistivity, and the dielectric constant for this situation. We then conduct (in the computer) hypothetical geophysical surveys at the surface of the model. These surveys are seismic refraction, microgravity, dc resistivity, and ground‐probing radar. Physical properties appropriate for cavities are then entered in the model. Repeating the geophysical surveys over the model with cavities provides a convenient method of evaluating their potential for cavity detection. Anomalies produced by normal variations in physical properties may simulate or obscure anomalies from target features. More data about the correlation of physical properties, particularly in the horizontal directions, will be required to evaluate this problem properly.

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Shallow Geophysical Techniques to Investigate the Groundwater Table at the Giza Pyramids Area, Giza, Egypt

10.5194/gi-2017-48 ◽

2017 ◽

Author(s):

Sharafeldin M. Sharafeldin ◽

Khalid S. Essa ◽

Mohamed A. S. Youssef ◽

Zein E. Diab

Keyword(s):

Water Table ◽

Ground Penetrating Radar ◽

Seismic Refraction ◽

Groundwater Table ◽

High Resistivity ◽

Electrical Resistivity Imaging ◽

Shallow Seismic ◽

Geophysical Techniques ◽

Electrical Resistivities ◽

Ground Penetrating

Abstract. Geophysical studies were performed along selected locations across the Pyramids Plateau to investigate the groundwater table and the near aquifer, which harmfully affected the existed monuments of the Giza Pyramids and Sphinx. Electrical Resistivity Imaging (ERI), Shallow Seismic Refraction (SSR) and Ground Penetrating Radar (GPR) techniques were carried out along selected profiles in the plateau. Ten ERI, twenty six SSR and nineteen GPR profiles were performed at the sites. The ERI survey shows that, the groundwater table is at elevations varying from 13 to 18 m above the sea level (asl) and low resistivity values near the surface at the Great Sphinx. ERI profiles, which were applied southeast of the Middle Pyramid (Khafre), show high resistivity values near the surface, and water table is located at elevations ranging from 22 to 40 m asl, while the ERI profiles conducted south of Menkaure, show almost high resistivity near the surface. The groundwater table is located at elevations ranging between 45 and 58 m asl. The aquifer layer shows electrical resistivities ranging between 10 and 50 Ohm.m. The considerable high change in the groundwater table is due to the rapid increases of topography from the Great Sphinx towards the Small Pyramids (Menkaure), where this part looks-like a scarp. The SSR Survey is transmitted to know the different velocities and types of the layers, which can help in knowing the saturated layers in the area. The GPR Survey is performed to delineate the water table, which gives good matching with the ERI results.

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Integration of Multi-geophysical Approaches to Identify Potential Pathways of Heavy Metals Contamination - A Case Study in Zeida, Morocco

Journal of Environmental and Engineering Geophysics ◽

10.32389/jeeg9-067 ◽

2020 ◽

Vol 25 (3) ◽

pp. 415-423

Author(s):

Ahmed Lachhab ◽

El Mehdi Benyassine ◽

Mohamed Rouai ◽

Abdelilah Dekayir ◽

Jean C. Parisot ◽

...

Keyword(s):

Heavy Metals ◽

Seismic Velocity ◽

Seismic Refraction ◽

Geophysical Methods ◽

Low Frequency ◽

Electrical Current ◽

P Wave ◽

Low Resistivity ◽

Refraction Tomography ◽

Geophysical Surveys

The tailings of Zeida's abandoned mine are found near the city of Midelt, in the middle of the high Moulouya watershed between the Middle and the High Atlas of Morocco. The tailings occupy an area of about 100 ha and are stored either in large mining pit lakes with clay-marl substratum or directly on a heavily fractured granite bedrock. The high contents of lead and arsenic in these tailings have transformed them into sources of pollution that disperse by wind, runoff, and seepage to the aquifer through faults and fractures. In this work, the main goal is to identify the pathways of contaminated water with heavy metals and arsenic to the local aquifers, water ponds, and Moulouya River. For this reason, geophysical surveys including electrical resistivity tomography (ERT), seismic refraction tomography (SRT) and very low-frequency electromagnetic (VLF-EM) methods were carried out over the tailings, and directly on the substratum outside the tailings. The result obtained from combining these methods has shown that pollutants were funneled through fractures, faults, and subsurface paleochannels and contaminated the hydrological system connecting groundwater, ponds, and the river. The ERT profiles have successfully shown the location of fractures, some of which extend throughout the upper formation to depths reaching the granite. The ERT was not successful in identifying fractures directly beneath the tailings due to their low resistivity which inhibits electrical current from propagating deeper. The seismic refraction surveys have provided valuable details on the local geology, and clearly identified the thickness of the tailings and explicitly marked the boundary between the Triassic formation and the granite. It also aided in the identification of paleochannels. The tailings materials were easily identified by both their low resistivity and low P-wave velocity values. Also, both resistivity and seismic velocity values rapidly increased beneath the tailings due to the compaction of the material and lack of moisture and have proven to be effective in identifying the upper limit of the granite. Faults were found to lie along the bottom of paleochannels, which suggest that the locations of these channels were caused by these same faults. The VLF-EM surveys have shown tilt angle anomalies over fractured areas which were also evinced by low resistivity area in ERT profiles. Finally, this study showed that the three geophysical methods were complementary and in good agreement in revealing the pathways of contamination from the tailings to the local aquifer, nearby ponds and Moulouya River.

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Physics-Based Relationship for Pore Pressure and Vertical Stress Monitoring Using Seismic Velocity Variations

Remote Sensing ◽

10.3390/rs13142684 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2684

Author(s):

Eldert Fokker ◽

Elmer Ruigrok ◽

Rhys Hawkins ◽

Jeannot Trampert

Keyword(s):

Pore Pressure ◽

Seismic Velocity ◽

Pressure Head ◽

Groundwater Table ◽

Surface Velocity ◽

Seismic Velocities ◽

Stress Monitoring ◽

Near Surface ◽

Velocity Variations ◽

Velocity Changes

Previous studies examining the relationship between the groundwater table and seismic velocities have been guided by empirical relationships only. Here, we develop a physics-based model relating fluctuations in groundwater table and pore pressure with seismic velocity variations through changes in effective stress. This model justifies the use of seismic velocity variations for monitoring of the pore pressure. Using a subset of the Groningen seismic network, near-surface velocity changes are estimated over a four-year period, using passive image interferometry. The same velocity changes are predicted by applying the newly derived theory to pressure-head recordings. It is demonstrated that the theory provides a close match of the observed seismic velocity changes.

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Surveying Batavia’s Graveyard: Geophysical controlled experiments and subsurface imaging of archaeological sites on an Indian Ocean coral island

Geophysics ◽

10.1190/geo2016-0531.1 ◽

2017 ◽

Vol 82 (4) ◽

pp. B147-B163 ◽

Cited By ~ 3

Author(s):

Jeffrey Shragge ◽

David Lumley ◽

Nader Issa ◽

Tom Hoskin ◽

Alistair Paterson ◽

...

Keyword(s):

Sea Water ◽

Controlled Experiments ◽

Near Surface ◽

Survey Techniques ◽

Geophysical Surveys ◽

Archaeological Materials ◽

Coral Island ◽

Water Saturated ◽

Ground Penetrating ◽

Geophysical Anomalies

We conducted geophysical surveys on Beacon Island in the Houtman Abrolhos archipelago offshore Western Australia, to investigate areas of archaeological interest related to the 1629 Batavia shipwreck, mutiny, and massacre. We used three complementary near-surface geophysical survey techniques (total magnetic intensity, electromagnetic induction mapping, and ground-penetrating radar) to identify anomalous target zones for archaeological excavation. Interpreting near-surface geophysical anomalies is often complex and nonunique, although it can be significantly improved by achieving a better understanding of site-specific factors including background conditions, natural variability, detectability limits, and the geophysical response to, and spatial resolution of, buried targets. These factors were not well-understood for Beacon Island nor indeed for the Australian coastal environment. We have evaluated the results of controlled experiments in which we bury known targets at representative depths and analyze the geophysical responses in terms of an ability to detect and resolve targets from natural background variability. The maximum depth of detectability of calibration targets on Beacon Island is limited to approximately 0.5 m due to significant variations in background physical properties between a thin ([Formula: see text]) and highly unconsolidated dry sand, shell, and coral layer of variable thickness overlying a sea-water-saturated sandy half-space. Our controlled measurements have implications for calibrating and quantifying the interpretation of geophysical anomalies in areas of archaeological interest, particularly in coastal and sandy-coral island environments. Our geophysical analyzes contributed to the discovery of archaeological materials and five historical burials associated with the 1629 Batavia shipwreck.

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Geophysical characterization of inactive/active rock glaciers in the semi-arid Andes using seismic, geoelectrics and GPR

10.5194/egusphere-egu2020-11808 ◽

2020 ◽

Author(s):

remi valois ◽

Nicole Schafer ◽

Giulia De Pasquale ◽

Gonzalo Navarro ◽

Shelley MacDonell

Keyword(s):

Electrical Resistivity ◽

Seismic Velocity ◽

Seismic Refraction ◽

Geophysical Methods ◽

Late Summer ◽

Relevant Information ◽

Refraction Tomography ◽

Rock Glaciers ◽

Ice Content ◽

Ground Penetrating

Rock glaciers play an important hydrological role in the semiarid Andes (SA; 27&#186;-35&#186;S). They cover about three times the area of uncovered glaciers and they are an important contribution to streamflow when water is needed most, especially during dry years and in the late summer months. Their characteristics such as their extension in depth and their ice content is poorly known. Here, we present a case study of one active rock glacier and periglacial inactive geoform in Estero Derecho (~30&#730;S), in the upper Elqui River catchment, Chile. Three geophysical methods (ground-penetrating radar and electrical resistivity and seismic refraction tomography) were combined to detect the presence of ice and understand the internal structure of the landform. The results suggest that the combination of electrical resistivity and seismic velocity provide relevant information on ice presence and their geometry. Radargrams shows diffraction linked to boulders presence but some information regarding electromagnetic velocity could be extracted. These results strongly suggest that such landforms contain ice, are therefore important to include in future inventories and should be considered when evaluating the hydrological importance of a particular region.&#160;

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High resolution GPR investigations employing single and multichannel systems in the Necropolis of Monte Abatone, Cerveteri (Roma, Italy).

10.5194/egusphere-egu2020-1883 ◽

2020 ◽

Author(s):

Salvatore Piro ◽

Bruna Malandruccolo

Keyword(s):

Ground Penetrating Radar ◽

Landscape Archaeology ◽

Dual Frequency ◽

Near Surface ◽

Complete Mapping ◽

Geophysical Surveys ◽

Near Surface Geophysics ◽

Anomalous Bodies ◽

And Migration ◽

Ground Penetrating

The Monte Abatone Necorpolis is one of the main important necropolis of Cerveteri, located 60 km north of Rome (Latium, Italy). In this area, several tombs have been discovered and excavated from the 1800, though still many remain hidden underneath the subsurface.In the last two years, geophysical surveys have been carried out to investigate the unexplored portions of the ancient Etruscan Necropolis, to provide a complete mapping of the position of the tombs. Ground Penetrating Radar and the Magnetometric methods have been used during 2018 to investigate few parts of the Necropolis. During 2019 (July and September) GPR system SIR 3000 (GSSI), equipped with a 400 MHz antenna with constant offset, SIR4000 (GSSI) equipped with a dual frequency antenna with 300/800 MHz and the 3D Radar Geoscope multichannel stepped frequency system were employed to survey 5 hectares where the presence of tombs was hypothesized from previous archaeological studies.All the GPR profiles were processed with GPR-SLICE v7.0 Ground Penetrating Radar Imaging Software (Goodman 2017). The basic radargram signal processing steps included: post processing pulse regaining; DC drift removal; data resampling; band pass filtering; background filter and migration. With the aim of obtaining a planimetric vision of all possible anomalous bodies, the time-slice representation technique was applied using all processed profiles showing anomalous sources up to a depth of about 2.5 m.The preliminary obtained results clearly show the presence of a network of strong circular features, linked with the buried structural elements of the searched tombs.Together with archaeologists, these anomalies, have been interpreted to have a better understanding of the archaeological definition of these features and to enhance the knowledge of the necropolis layout and mapping; after the geophysical surveys, excavations have been conducted, which brought to light few of the investigated structures.&#160;ReferencesCampana S., Piro S., 2009. Seeing the Unseen. Geophysics and Landscape Archaeology. Campana & Piro Editors. CRC Press, Taylor & Francis Group. Oxon UK, ISBN 978-0-415-44721-8.Goodman, D., Piro, S., 2013. GPR Remote sensing in Archaeology, Springer: Berlin.Piro S., Papale E., Zamuner D., Kuculdemirci M., 2018. Multimethodological approach to investigate urban and suburban archaeological sites. In &#8220;Innovation in Near Surface Geophysics. Instrumentation, application and data processing methods.&#8221;, Persico R., Piro S., Linford N., Ed.s. pp. 461 &#8211; 504, ISBN: 978-0-12-812429-1, pp.1-505, Elsevier.

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Combining Resistivity and Aeromagnetic Geophysical Surveys for Groundwater Exploration in the Maghnia Plain of Algeria

Journal of Geological Research ◽

10.1155/2017/1309053 ◽

2017 ◽

Vol 2017 ◽

pp. 1-14 ◽

Cited By ~ 3

Author(s):

Djamel Boubaya

Keyword(s):

Groundwater Potential ◽

Groundwater Exploration ◽

Magnetic Data ◽

Geoelectric Section ◽

Resistive Layer ◽

Near Surface ◽

Groundwater Aquifer ◽

Geophysical Surveys ◽

Schlumberger Sounding ◽

Topsoil Layer

The Maghnia plain in western Algeria is filled by Plio-Quaternary and Miocene sediments that rest unconformably on a basement of Jurassic rocks. Electrical sounding (VES), magnetic data, well information, and hydrogeological data have been used to explore for groundwater potential in the Maghnia plain. The interpretation of Schlumberger sounding data was first calibrated with the lithology of available nearby wells. Four geoelectrical layers were identified within the study area. They are a thin near surface topsoil layer with variable resistivities, a moderate resistive aquifer (15–30 ohm-m), a resistive aquifer (40–70 ohm-m), and a conductive clay layer (1–10 ohm-m). Near Sidi Mbarek, the geoelectric section is reduced to three layers: a topsoil layer, a conductive layer corresponding to the Miocene marls, and a deep resistive layer that correlates with the Oxfordian sandstones. The interpretation of VES data and the enhancement techniques of magnetic data enabled the identification of a number of unmapped faults that occur near recharge zones close to adjacent mountains. This study enabled us to study the extension of the known Plio-Quaternary aquifer of the Maghnia plain and to explore the possible existence of a second deep groundwater aquifer in Oxfordian sandstones.

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Geophysical investigation to assess condition of grouted scour hole : Old River Control Complex—Low Sill Concordia Parish, Louisiana

10.21079/11681/41863 ◽

2021 ◽

Author(s):

Janet Simms ◽

Benjamin Breland ◽

William Doll

Keyword(s):

Seismic Refraction ◽

Low Frequency ◽

Borehole Data ◽

Geophysical Investigation ◽

Seismic Surveys ◽

Geophysical Surveys ◽

River Control ◽

Ground Penetrating ◽

Control Complex ◽

Water Borne

Geophysical surveys, both land-based and water-borne, were conducted at the Old River Control Complex‒Low Sill, Concordia Parish, LA. The purpose of the surveys was to assess the condition of the grout within the scour region resulting from the 1973 flood event, including identification of potential voids within the grout. Information from the ground studies will also be used for calibration of subsequent marine geophysical data and used in stability analysis studies. The water-borne survey consisted of towed low frequency (16-80 MHz) ground penetrating radar (GPR), whereas the land-based surveys used electrical resistivity and seismic refraction. The GPR survey was conducted in the Old River Channel on the upstream side of the Low Sill structure. The high electrical conductivity of the water (~50 mS/m) precluded penetration of the GPR signal; thus, no useful data were obtained. The land-based surveys were performed on both northeast and southeast sides of the Low Sill structure. Both resistivity and seismic surveys identify a layered subsurface stratigraphy that corresponds, in general, with available borehole data and constructed geologic profiles. In addition, an anomalous area on the southeast side was identified that warrants future investigation and monitoring.

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Localization of Deep Voids through Geophysical Signatures of Secondary Dewatering Features

Geophysics ◽

10.1190/geo2020-0491.1 ◽

2021 ◽

pp. 1-81

Author(s):

Dan R. Glaser ◽

Katrina Burch ◽

Dennis L. Brinkley ◽

Philip Reppert

Keyword(s):

Seismic Refraction ◽

Geophysical Methods ◽

Mixing Model ◽

Time Domain Reflectometry ◽

Groundwater Table ◽

Void Space ◽

Investigation Area ◽

Measurement Geometry ◽

Lateral Localization ◽

Ground Penetrating

Discrete deep targets are a significant challenge for most surface-based geophysical techniques, even when considering high property contrasts. Generally, surface-based geophysical methods lose lateral and vertical resolution with depth as a result of poor measurement geometry and increased signal attenuation. The poor measurement geometry can be overcome through use of cross-borehole methods, but lateral localization is still needed for optimal borehole placement. As such, a relatively small, deep void located near the maximum depth of investigation is very unlikely to be detected. Yet, secondary features associated with these voids can be exploited for enhanced detection performance. When voids are located below the groundwater table a significant amount of dewatering and pumping is required to make them a functional passageway. This dewatering not only removes water from the void space but also the surrounding formation, resulting in a much larger, if more diffuse, secondary target: an induced groundwater table gradient. Many geophysical sensing methods are sensitive to subsurface moisture content. Here we implement a two-dimensional (2D) joint-petrophysical mixing-model, using inverted electrical resistivity tomography and inverted seismic refraction models to sense changes in the groundwater table gradient. Results are validated using depth to bedrock, groundwater-surface water information, ground-penetrating radar, and time-domain reflectometry methods. Our initial proof of concept is applied to a shallow area with a significant soil moisture gradient, through different surface soil types and bedrock. The 2D joint-petrophysical mixing-model results were used to generate an estimate of air, moisture, and matrix percent fractions in the investigation area, providing a clear delineation of the groundwater surface.

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