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Mohamed Attwa

Zagazig University, Geology Department, Faculty Member

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Phone: 00201096176633
Address: Zagazig University, faculty of Science, Geology department, Zagazig, 44915, Egypt

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Mohamed A . Taha

National Research Institute Of Astronomy And Geophysics Nriag

Universidade de Brasília - UnB

University of Calabar

mohamed eleraki

Suez Canal University

Zagazig University

abdelaziz El Shinawi

Zagazig University

Zagazig University

Zagazig University

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Papers by Mohamed Attwa

$Research paper thumbnail of Geotechnical assessment of fractured limestone bedrock using DC resistivity method: a case study at New Minia City, Egypt$

Geotechnical assessment of fractured limestone bedrock using DC resistivity method: a case study at New Minia City, Egypt

NRIAG Journal of Astronomy and Geophysics, 2020

The new urban development is an important priority in Egypt to face a rapid increase in the popul... more The new urban development is an important priority in Egypt to face a rapid increase in the population during the last few decades. As a case study, the geotechnical assessment of the New Minia City is studied applying direct current (DC) resistivity technique. In the presented study, the DC resistivity data are interpreted to (i) characterize the subsurface layer distributions, (ii) deduce the subsurface structures considering the surface geological and structural setting and borehole information and (iii) predict geotechnical parameters of the bedrock based on empirical relationships. The inversion results of DC resistivity data indicate that a lens of clay is locally capping the fractured limestone in different parts of the area. The constructed geoelectrical cross-sections show that the limestone bedrock is highly fractured regarding many normal faults trending in the NW and NE directions. In an attempt to derive empirical relationships for predicting the geotechnical parameters, the inverted resistivity values of the fractured limestone were correlated with different geotechnical parameters, Rock Quality Designation (RQD) and Unconfined Compressive Strength (UCS). It is noticed that there are good correlations between the limestone resistivity values and geotechnical parameters obtained from borehole data applying linear relations. Accordingly, the results indicate that the DC resistivity method constitutes a valuable technique to introduce a preliminary geotechnical assessment for new urban areas.

Flash Flood Management and Harvesting Via Groundwater Recharging in Wadi Systems: An Integrative Approach of Remote Sensing and Direct Current Resistivity Techniques

Flash Floods in Egypt, 2020

Interactive comment on “Spectral induce polarization measurements for environmental purposes and predicting the hydraulic conductivity in sandy aquifers” by M. Attwa and T. Günther

Structural Geophysics Investigations using GIS and DC Resistivity Techniques: Hydrogeological Implications of Wadi Ramleiya, Eastern Desert, Egypt

Asian Journal of Applied Sciences, 2018

In this study, an integrated suite of geological and direct current resistivity (DCR) data is use... more In this study, an integrated suite of geological and direct current resistivity (DCR) data is used to evaluate the hydrogeophysical conditions at the downstream part of Wadi Ramleiya, Eastern Desert, Egypt. Geological and morphometric analysis of drainage basin and DCR measurements in the form of 1D and 2D surveys are carried out to reveal the subsurface layer distributions and demonstrate the groundwater potentialities. It is obviously that the shallow aquifers and groundwater flow direction are related to structural controls. Based on the inversion results of DCR data, the aquifer is under unconfined conditions where it rests on layers of argillaceous limestone and overlain by gravelly sand. Accordingly, the obtained results can serve as a basis for monitoring, planning and management of water resources in such desert area, and as a whole, they constitute an encouraging example using an integrated approach of geological, morphometric and DCR data in groundwater exploration and fla...

Application of Spectral Induced Polarization (SIP) Imaging for Characterizing the Near-Surface Geology: An Environmental Case Study at Schillerslage, Germany

Spectral induced polarization (SIP) imaging is a promising tool for environmental studies. Applic... more Spectral induced polarization (SIP) imaging is a promising tool for environmental studies. Application of this method for the near-surface investigations has previously been limited by incomplete understanding of the physicochemical controls on the IP response, with a lack of appropriate methods for data inversion. We aim to study the applicability of the 2D IP imaging for resolving the near-surface sediment heterogeneity, as well as the Quaternary aquifer at Schillerslage test-site in the north of Germany. An SIP survey was carried out along four profiles with dipole-dipole configuration using different electrode spacings. Multi-frequency data were recorded and inverted with a 2D smoothness constrained inversion to obtain the 2D images of conductivity magnitude, phase, real and imaginary parts of conductivity for each frequency. Displaying all these parameters is redundant, but reflects different subsurface characteristics. The 2D inversion results were correlated with the borehole...

Toward an Integrated and Sustainable Water Resources Management in Structurally-Controlled Watersheds in Desert Environments Using Geophysical and Remote Sensing Methods

Sustainability, 2021

Sustainable water resources management in desert environment has yet to be reached due to the lim... more Sustainable water resources management in desert environment has yet to be reached due to the limited hydrological datasets under such extreme arid conditions. In the Eastern Sahara, the tectonic activity associated with the opening of the Red Sea adds more complexity to developing sustainable water management by creating multiple aquifers within subsided half-grabens along the Red Sea extension. To overcome these difficulties, a two-fold approach is adopted including integrated remote sensing and geoelectrical methods using Wadi Al-Ambagi watershed in the Eastern Desert of Egypt as a test site. First, the total discharge is estimated as 15.7 × 106 m3 following the application of a uniform storm of 10 mm effective precipitation, which exceeds the storage capacity of existing mitigation measures (5.5 × 106 m3), and thus additional dams are required. Second, the subsurface geometry of alluvium and sedimentary aquifers, within subsided blocks in the Arabian–Nubian shield (ANS), is deli...

Detection and Prediction of Geo-environmental Hazards in Urban Areas and Desert Lands Using an Integrated Structural and Geophysical Approach: Cases from Egypt

Waste Management in MENA Regions, 2019

Nowadays, geo-environmental assessment becomes an immediate concern all over the world. In genera... more Nowadays, geo-environmental assessment becomes an immediate concern all over the world. In general, the flow paths of pollutants and radioactive source allocations are related to rock types, subsurface layer distributions and structural settings. Thus, this chapter aims to present a non-conventional integrative approach of remote sensing, structural data and geophysical methods for geo-environmental hazard assessment. Notably, such hazards commonly result from human activities where contaminants are accumulated and spread on or beneath the ground surface. Detection of organic contamination and hydrocarbon flow path is a difficult task for geophysical techniques at hazardous waste areas. Furthermore, radioactive-emission detection is of specific value in the vicinity of mineral resources for human health and environmental preservation. Accordingly, waste management as well as a subsurface contaminant and geological structure mapping are prerequisite for urbanization, mining and civil...

Soil Characterization Using Joint Interpretation of Remote Sensing, Resistivity and Induced Polarization Data along the Coast of the Nile Delta

Natural Resources Research, 2021

Soil characterization in coastal areas is essential for strategic coastal engineering implementat... more Soil characterization in coastal areas is essential for strategic coastal engineering implementation and for understanding the paleo-environmental conditions. However, the severe soil salinization in these regions limited the geophysical measurements to shallow depths and conventional drilling is time-consuming and cumbersome. Here, we integrate remote sensing (RS), direct current resistivity (DCR) and time-domain induced polarization (TDIP) to characterize the soil along the Nile Delta coast. To avoid the impact of the recent human-made topographic artifacts, a high-resolution digital elevation model is produced using old topographic sheets. Consequently, the defunct Holocene streams/buried channels can be extracted. Regarding multi-temporal multispectral and multispectral RS data, land use–land cover maps (LU–LC) indicate that the sabkha/waterlogged areas significantly increased while coastal sand and sand dunes dwindled with a rapid rate of expansion of new urban areas. Applying linear and nonlinear geophysical inversion schemes, the coastal soil heterogeneities are characterized using 1D/2D resistivity and 2D-TDIP measurements with the consideration of the geomorphologic and borehole data, as well as the cone penetration test (CPTu). The geophysical results indicate that the dominance of sandy sediments occurs along the channels and sand dunes sites. Obviously, the discrimination between saturated coastal sandy and clayey soils cannot be attained using individual 2D-DCR tomograms. On the other hand, clay and silt sediments can be well characterized, where the waterlogged areas are dominant, from the high-resolution TDIP inversion. Accordingly, the present protocol can be readily applied along the deltaic coasts subject to heavy anthropogenic activities for prioritized engineering interventions.

Resistivity Characterization of Aquifer in Coastal Semiarid Areas: An Approach for Hydrogeological Evaluation

The Handbook of Environmental Chemistry, 2018

In coastal and semiarid regions, the scientific interest lies in imaging the saltwater intrusion ... more In coastal and semiarid regions, the scientific interest lies in imaging the saltwater intrusion and delineating freshwater aquifer zones, respectively. Direct current resistivity (DCR) and induced polarization (IP) geophysical methods are commonly used to assess hydraulic characteristics of the aquifer. Particularly, the main reason for hydrogeophysical application of both DCR and IP is that the electrical characteristics of aquifers depend mainly on the geometry of the pore space and the porosity controlling the soil and rock effective transport properties. For preliminary hydrogeological investigations, these methods are applied at a wide range of field and laboratory scales. Accordingly, the vulnerable zone to the saltwater intrusion and/or contamination can be characterized by high accuracy. Furthermore, empirical and semiempirical relationships are widely used to predict the aquifer petrophysical characteristics, e.g., hydraulic conductivity, using the inversion results of such electrical methods. Equally, conventional and nonconventional DCR inversion algorithms are developed to reduce the nonuniqueness problem of actual resistivity interpretation and, consequently, to obtain more meaningful models than previously reported. As case histories, this chapter demonstrates the efficiency of DCR method for hydrogeological assessment in Nile Delta, Egypt, emphasizing on technical constraints to achieve sustainable development in coastal and semiarid areas.

Modeling Flash Floods and Induced Recharge into Alluvial Aquifers Using Multi-Temporal Remote Sensing and Electrical Resistivity Imaging

Sustainability, 2020

Flash flood hazard assessments, mitigation measures, and water harvesting efforts in desert envir... more Flash flood hazard assessments, mitigation measures, and water harvesting efforts in desert environments are often challenged by data scarcity on the basin scale. The present study, using the Wadi Atfeh catchment as a test site, integrates remote sensing datasets with field and geoelectrical measurements to assess flash flood hazards, suggest mitigation measures, and to examine the recharge to the alluvium aquifer. The estimated peak discharge of the 13 March 2020 flood event was 97 m3/h, which exceeded the capacity of the culverts beneath the Eastern Military Highway (64 m3/h), and a new dam was suggested, where 75% of the catchment could be controlled. The monitoring of water infiltration into the alluvium aquifer using time-lapse electrical resistivity measurements along a fixed profile showed a limited connection between the wetted surficial sediments and the water table. Throughflow is probably the main source of recharge to the aquifer rather than vertical infiltration at the ...

An integrated approach of GIS and geoelectrical techniques for wastewater leakage investigations: Active constraint balancing and genetic algorithms application

Journal of Applied Geophysics, 2020

Abstract Wastewater leakage problem associated with sewage treatment plants deterioration has bec... more Abstract Wastewater leakage problem associated with sewage treatment plants deterioration has become prominent. We develop and apply procedures of GIS and direct current resistivity (DCR) techniques to investigate the wastewater seepage appearance in a semiarid urban environment. In the first stage, all surface geological and structural information is manipulated using GIS to produce geomorphological and geological maps. Waterlogged sites resulting in land degradation are distinguished by monitoring land-use/land-cover (LU/LC) changes. In the second stage, the DCR method has been performed to characterize the subsurface layer distributions and structures considering the results of GIS and LU/LC mapping data. Because the geophysical inverse problem is usually ill-posed, the active constrain balancing (ACB) approach and genetic algorithms (GA) are applied to optimize the inversion results. In the presence of high conductive layers, the limitation of DCR imaging in detecting the subsurface structure is demonstrated from the synthetic data. Moreover, we demonstrate that the joint use of GA with structure-based model (SBM) is helpful in recognition of subsurface layer distributions with non-smooth interfaces. However, ACB approach is more practical for lateral heterogeneities determination within the same rock unit than SBM with GA approach. The results indicate that the waterlogged areas and wastewater migration pathways are mainly controlled by the drainage networks and subsurface structures. Notably, the integrated approach allows us to assess geotechnical problems and to propose a suitable location for wastewater discharge management. Finally, the study can be considered as a scientific basis for desert urbanization and rational urban development planning.

Tracing Holocene channels and landforms of the Nile Delta through integration of early elevation, geophysical, and sediment core data

The Holocene, 2020

Intensification of anthropogenic activities and related processes have altered the morphology of ... more Intensification of anthropogenic activities and related processes have altered the morphology of modern deltaic systems. As a result, mapping of geomorphic features, such as paleochannels, using recently acquired digital elevation data has become increasingly difficult. Using the Nile River and delta as a test site, we developed and applied procedures to map the distribution of paleochannels that existed throughout the Holocene. A high-resolution digital elevation model (DEM) derived from an early, detailed topographic sheet collection was used to minimize the impact of recent man-made topographic artifacts. The DEM-inferred paleochannel distribution was verified using direct and indirect subsurface data. Using our adopted methodology, we identified 76 main and subsidiary paleochannels with a total length exceeding (by >500 km) previously mapped paleochannels. The overwhelming majority (>80%) of the reported historical and archeological sites (29 sites) in the Nile Delta were ...

Imaging of wastewater percolation in heterogeneous soil using electrical resistivity tomography (ERT): a case study at east of Tenth of Ramadan City, Egypt

Environmental Earth Sciences, 2017

Abstract The objective of this study is to evaluate the effectiveness of DC resistivity surveys f... more Abstract The objective of this study is to evaluate the effectiveness of DC resistivity surveys for imaging the wastewater percolation around the stabilization ponds in the Tenth of Ramadan City, the desert fringes of East Nile Delta, Egypt. Detailed resistivity surveys, including DC soundings and electrical resistivity tomography (ERT), were carried out along several profiles. Furthermore, synthetic modeling of ERT was designed to optimize the survey configurations and interpretation of the results. A 2D modeling of smoothness-constrained least-squares inversion scheme was applied to delineate the possible wastewater infiltration zones from oxidation ponds. Because the geoelectrical interpretation has a degree of non-uniqueness, the resistivity inversion was constrained using borehole lithological information and soil sample laboratory measurements. The DC inversion results indicate decreasing resistivity down to a depth of 15 m around waste disposal sites. The inferred soil zone close to the oxidation ponds was a mixture of sand, silt and clay. Moreover, the clay minerals were characterized by moderate swelling that could have reduced the vertical infiltration speed, causing wastewater seepage, especially around unlined disposal sites and open surface drains. Accordingly, the medium-to-low resistivity values can be attributed to wastewater leakage in clayey sand soil. Because the area slopes generally toward the northeast, the surface seepage was dominant in the shallow impermeable sandy clay subsoil. Therefore, measuring soil parameters is a complementary method to optimize resistivity interpretation, with potential for mitigating environmental hazards from wastewater leakage around disposal ponds.

Internal structural architecture of a soft-linkage transfer zone using outcrop and DC resistivity data: Implications for preliminary engineering assessment

Engineering Geology, 2018

Abstract The current study presents a new integrative approach for detailed structural mapping of... more Abstract The current study presents a new integrative approach for detailed structural mapping of a soft-linkage transfer zone using outcrop, boreholes and DCR data in the form of soundings and 2D-electrical resistivity tomography (2D-ERT). As a case study, the present approach is implied for studying the geo-engineering conditions of a highly deformed desert-land entry to reclaim at Cairo-Suez district, Egypt. The approach has led to the spatial understanding of the subsurface heterogeneity and complex structures at a level of accuracy unattainable with traditional surface structural mapping alone. For preliminary geotechnical assessment, some physical and geotechnical properties are characterized by field and laboratory measurements for collected soil samples. Moreover, the inverted DCR data are used to predict the RQD values using a polynomial relationship between RQD and the intrinsic resistivity (ρ). Notably, the calculated and actual values of RQD are, in general, in the same order considering the error factor value, and hence, the derived equation for RQD prediction is satisfactory. Therefore, the proposed approach reduces the uncertainty of the constructed structural model for engineering design. In addition, merging outcrop with DCR data allows us with a limited frame of time to partially mitigate disasters to civilization by better (i) potential location understanding and (ii) remediation plans tuning for a complex structured site.

Flash floods and groundwater evaluation for the non-gauged dryland catchment using remote sensing, GIS and DC resistivity data: A case study from the Eastern Desert of Egypt

Journal of African Earth Sciences, 2019

Abstract The coastal and alluvial areas of the Red Sea Mountains are mainly being developed for r... more Abstract The coastal and alluvial areas of the Red Sea Mountains are mainly being developed for resorts and tourism activities. Given the development of occasional flash floods in the central part of the Red Sea area can be of destructive consequences to the various anthropogenic activities; thus the quantitative and qualitative assessments of the hydrological parameters and groundwater occurrence are presented. As a case study, Wadi Isl at the Red Sea coast has been hydrogeologically analyzed using an integrative approach of remote sensing, GIS and direct current resistivity (DCR) tools. The time area-zones have been estimated using and Manning's equation into the spatial analyses routines embedded within the ArcGIS. In this study, a synthetic effective rainfall of 10 mm has been applied to compute the spatially distributed runoff hydrograph. The estimated total runoff volume is approximately 8 million cubic meters, and the peak discharge rate is estimated to 163 cubic meters per second, which can be destructive to the main infrastructures in the flash flood pathways. Then, the 2D-electrical resistivity tomography (2D-ERT) surveys have been carried out at various localities along the main wadi course to explore the lateral and vertical variation of alluvium thickness and the saturated zones. Notably, the groundwater occurrence is contained in the structurally controlled graben. Therefore, the study has recommended the construction a main barrier at a natural deep gorge of the main outlet in order to fully control the flash floods and to enhance the potential recharge to the underlying alluvium aquifer. The present integrative approach of both surface and subsurface data is definitely needed to maximize the flash flood benefits.

An integrative approach for preliminary environmental engineering investigations amidst reclaiming desert-land: a case study at East Nile Delta, Egypt

Environmental Earth Sciences, 2017

Scientific interest within the desert-lands lies on mapping the near-surface clayey soils being m... more Scientific interest within the desert-lands lies on mapping the near-surface clayey soils being made environmental engineering problems, e.g., water logging and cracked pavements. As a starting point used for urban rational development, boreholes, direct current resistivity (DCR) soundings and electrical resistivity tomography surveys and preliminary geotechnical studies are employed in an integrative approach for mapping and characterizing the foundation soil. This study is carried out at one of the main urban reclamation projects amidst desert fringes of East Nile Delta, Egypt, as a case study, where the in situ soil properties are variable even within a short distance and, consequently, difficult to be predicted. Conventional and non-conventional inversion approaches are applied for solving the inverse problems of DCR data. The results are calibrated with the drilled borehole lithology. Two main geoelectrical resistivity layers are distinguished: the upper medium to high-resistivity soils corresponding to surface poorly graded sand with gravels underlain by low-resistivity layer attributing to clayey sand with calcareous materials. The inversion results show the sequential joint use efficiency of the two approaches in mapping the near-surface layer boundaries providing realistic soil heterogeneities tomography. In respect of such results and from an engineering point of view, the exaggerated clayey soils are highly saturated in some places representing (1) medium plasticity, moderate-to-high swelling and (2) low compressive strength. It is conceivable that such soils can exhibit geotechnical problems, especially under wetting conditions. Consequently, the integrative approach is cost-effective and opens the way for engineers on where prioritized interventions are required to the urban expansion.

Use of salinity and resistivity measurements to study the coastal aquifer salinization in a semi-arid region: a case study in northeast Nile Delta, Egypt

Environmental Earth Sciences, 2016

To understand the impact of sea level rise (SLR) and aquifer intensive use would cause to the gro... more To understand the impact of sea level rise (SLR) and aquifer intensive use would cause to the groundwater level and saltwater intrusion, an integrated relationship between salinity and electrical resistivity of a Quaternary aquifer is established in the northern part of East Nile Delta (El Sharkia area), Egypt. Historical data of groundwater salinity are mapped and compared with the current water samples to better understand the salinity spatial variability. The salinity maps show that salinization has increased sustainably. Additionally, the transition/dynamic zone related to SLR and/or excessive pumping can be addressed. In particular, the surface DC resistivity soundings were carried out to demonstrate the vertical and horizontal salinity distributions in the area. In the course of this study, the 1D model generation using a hybrid genetic algorithm (GA) was applied and tested using borehole information. The constructed geoeletrical cross-sections emphasize and delineate the extension of saltwater intrusion. Cleary, it is found that due to excessive pumping from shallow wells over the last decades, the subsurface resistivity and TDS vertical distributions can change rapidly within a short distance. Additionally, the results show that despite the dominance of brackish and saltwater at the northern part of the area, perched low conductive lenses are observed reflecting a low level of groundwater salinization. To obtain a link between water salinity and aquifer resistivity, an empirical relationship was derived to predict the salinity variations at different depths. In comparison with the measured total dissolved solids (TDS), the predicted salinity map appears realistic. These results demonstrate the important role of the integration between resistivity and salinity measurements for mapping the groundwater salinization with depth, and call for further research to plan and manage the area's water resources.

Assessment of oxidation ponds impact using DC resistivity method in Tenth of Ramadan city, Egypt

A large quantity of wastewater is collected in three oxidation ponds raising serious environmenta... more A large quantity of wastewater is collected in three oxidation ponds raising serious environmental concern in the east of Tenth of Ramadan city, Egypt. In the present work, the DC resistivity method in the form of 1D and 2D was applied for wastewater percolation monitoring in the area around the oxidation ponds. The resistivity measurements were integrated with laboratory studies of soil samples to estimate grain size, porosity, clay contents and degree of saturation. According to the former Schlumberge sounding survey, six 2D resistivity profiles were measured closed to the ponds. Wenner beta and Pole-dipole electrode arrays were selected for 2D resistivity imaging based on a prior synthetic modelling. The 1D model generation and verification by the use of genetic algorithms (GA) represent an accurate quick solution to the subsurface resistivity layer distributions. A conventional derivative-based inversion with cell-model provides valuable constraints to interpret the 2D resistivi...

Electrical Methods: Practical Guide for Resistivity Imaging and Hydrogeophysics

This book constitutes an encouraging example using electrical methods (DC, FDEM and SIP) in chara... more This book constitutes an encouraging example using electrical methods (DC, FDEM and SIP) in characterizing the coastal aquifer. The geophysical inversion results are represented in form of 1D, 2D and 3D imaging. Both DC sensitivity analysis and synthetic modeling are discussed in details. In addition, the joint inversion of different arrays is assessed to improve the model reliability especially under no or limited prior geological information. The intention here also is to establish an empirical relationship between the aquifer resistivity and the aquifer hydraulic parameters using the DC soundings. Published data from Nigeria and India is used to establish this equation. In Germany, DC soundings and 2D SIP data was used to investigate the hydrogeophysical conditions of tidal deposits. This book provides a ‘crash course’ in the new frontiers of environmental and hydrogeophysics.

Application of genetic algorithm (GA) for soil characterization using DC resistivity data: A case study in Tenth of Ramadan city, Egypt

Advances in Natural and Applied Sciences

$Research paper thumbnail of Geotechnical assessment of fractured limestone bedrock using DC resistivity method: a case study at New Minia City, Egypt$

Geotechnical assessment of fractured limestone bedrock using DC resistivity method: a case study at New Minia City, Egypt

NRIAG Journal of Astronomy and Geophysics, 2020

The new urban development is an important priority in Egypt to face a rapid increase in the popul... more The new urban development is an important priority in Egypt to face a rapid increase in the population during the last few decades. As a case study, the geotechnical assessment of the New Minia City is studied applying direct current (DC) resistivity technique. In the presented study, the DC resistivity data are interpreted to (i) characterize the subsurface layer distributions, (ii) deduce the subsurface structures considering the surface geological and structural setting and borehole information and (iii) predict geotechnical parameters of the bedrock based on empirical relationships. The inversion results of DC resistivity data indicate that a lens of clay is locally capping the fractured limestone in different parts of the area. The constructed geoelectrical cross-sections show that the limestone bedrock is highly fractured regarding many normal faults trending in the NW and NE directions. In an attempt to derive empirical relationships for predicting the geotechnical parameters, the inverted resistivity values of the fractured limestone were correlated with different geotechnical parameters, Rock Quality Designation (RQD) and Unconfined Compressive Strength (UCS). It is noticed that there are good correlations between the limestone resistivity values and geotechnical parameters obtained from borehole data applying linear relations. Accordingly, the results indicate that the DC resistivity method constitutes a valuable technique to introduce a preliminary geotechnical assessment for new urban areas.

Flash Flood Management and Harvesting Via Groundwater Recharging in Wadi Systems: An Integrative Approach of Remote Sensing and Direct Current Resistivity Techniques

Flash Floods in Egypt, 2020

Interactive comment on “Spectral induce polarization measurements for environmental purposes and predicting the hydraulic conductivity in sandy aquifers” by M. Attwa and T. Günther

Structural Geophysics Investigations using GIS and DC Resistivity Techniques: Hydrogeological Implications of Wadi Ramleiya, Eastern Desert, Egypt

Asian Journal of Applied Sciences, 2018

In this study, an integrated suite of geological and direct current resistivity (DCR) data is use... more In this study, an integrated suite of geological and direct current resistivity (DCR) data is used to evaluate the hydrogeophysical conditions at the downstream part of Wadi Ramleiya, Eastern Desert, Egypt. Geological and morphometric analysis of drainage basin and DCR measurements in the form of 1D and 2D surveys are carried out to reveal the subsurface layer distributions and demonstrate the groundwater potentialities. It is obviously that the shallow aquifers and groundwater flow direction are related to structural controls. Based on the inversion results of DCR data, the aquifer is under unconfined conditions where it rests on layers of argillaceous limestone and overlain by gravelly sand. Accordingly, the obtained results can serve as a basis for monitoring, planning and management of water resources in such desert area, and as a whole, they constitute an encouraging example using an integrated approach of geological, morphometric and DCR data in groundwater exploration and fla...

Application of Spectral Induced Polarization (SIP) Imaging for Characterizing the Near-Surface Geology: An Environmental Case Study at Schillerslage, Germany

Spectral induced polarization (SIP) imaging is a promising tool for environmental studies. Applic... more Spectral induced polarization (SIP) imaging is a promising tool for environmental studies. Application of this method for the near-surface investigations has previously been limited by incomplete understanding of the physicochemical controls on the IP response, with a lack of appropriate methods for data inversion. We aim to study the applicability of the 2D IP imaging for resolving the near-surface sediment heterogeneity, as well as the Quaternary aquifer at Schillerslage test-site in the north of Germany. An SIP survey was carried out along four profiles with dipole-dipole configuration using different electrode spacings. Multi-frequency data were recorded and inverted with a 2D smoothness constrained inversion to obtain the 2D images of conductivity magnitude, phase, real and imaginary parts of conductivity for each frequency. Displaying all these parameters is redundant, but reflects different subsurface characteristics. The 2D inversion results were correlated with the borehole...

Toward an Integrated and Sustainable Water Resources Management in Structurally-Controlled Watersheds in Desert Environments Using Geophysical and Remote Sensing Methods

Sustainability, 2021

Sustainable water resources management in desert environment has yet to be reached due to the lim... more Sustainable water resources management in desert environment has yet to be reached due to the limited hydrological datasets under such extreme arid conditions. In the Eastern Sahara, the tectonic activity associated with the opening of the Red Sea adds more complexity to developing sustainable water management by creating multiple aquifers within subsided half-grabens along the Red Sea extension. To overcome these difficulties, a two-fold approach is adopted including integrated remote sensing and geoelectrical methods using Wadi Al-Ambagi watershed in the Eastern Desert of Egypt as a test site. First, the total discharge is estimated as 15.7 × 106 m3 following the application of a uniform storm of 10 mm effective precipitation, which exceeds the storage capacity of existing mitigation measures (5.5 × 106 m3), and thus additional dams are required. Second, the subsurface geometry of alluvium and sedimentary aquifers, within subsided blocks in the Arabian–Nubian shield (ANS), is deli...

Detection and Prediction of Geo-environmental Hazards in Urban Areas and Desert Lands Using an Integrated Structural and Geophysical Approach: Cases from Egypt

Waste Management in MENA Regions, 2019

Nowadays, geo-environmental assessment becomes an immediate concern all over the world. In genera... more Nowadays, geo-environmental assessment becomes an immediate concern all over the world. In general, the flow paths of pollutants and radioactive source allocations are related to rock types, subsurface layer distributions and structural settings. Thus, this chapter aims to present a non-conventional integrative approach of remote sensing, structural data and geophysical methods for geo-environmental hazard assessment. Notably, such hazards commonly result from human activities where contaminants are accumulated and spread on or beneath the ground surface. Detection of organic contamination and hydrocarbon flow path is a difficult task for geophysical techniques at hazardous waste areas. Furthermore, radioactive-emission detection is of specific value in the vicinity of mineral resources for human health and environmental preservation. Accordingly, waste management as well as a subsurface contaminant and geological structure mapping are prerequisite for urbanization, mining and civil...

Soil Characterization Using Joint Interpretation of Remote Sensing, Resistivity and Induced Polarization Data along the Coast of the Nile Delta

Natural Resources Research, 2021

Soil characterization in coastal areas is essential for strategic coastal engineering implementat... more Soil characterization in coastal areas is essential for strategic coastal engineering implementation and for understanding the paleo-environmental conditions. However, the severe soil salinization in these regions limited the geophysical measurements to shallow depths and conventional drilling is time-consuming and cumbersome. Here, we integrate remote sensing (RS), direct current resistivity (DCR) and time-domain induced polarization (TDIP) to characterize the soil along the Nile Delta coast. To avoid the impact of the recent human-made topographic artifacts, a high-resolution digital elevation model is produced using old topographic sheets. Consequently, the defunct Holocene streams/buried channels can be extracted. Regarding multi-temporal multispectral and multispectral RS data, land use–land cover maps (LU–LC) indicate that the sabkha/waterlogged areas significantly increased while coastal sand and sand dunes dwindled with a rapid rate of expansion of new urban areas. Applying linear and nonlinear geophysical inversion schemes, the coastal soil heterogeneities are characterized using 1D/2D resistivity and 2D-TDIP measurements with the consideration of the geomorphologic and borehole data, as well as the cone penetration test (CPTu). The geophysical results indicate that the dominance of sandy sediments occurs along the channels and sand dunes sites. Obviously, the discrimination between saturated coastal sandy and clayey soils cannot be attained using individual 2D-DCR tomograms. On the other hand, clay and silt sediments can be well characterized, where the waterlogged areas are dominant, from the high-resolution TDIP inversion. Accordingly, the present protocol can be readily applied along the deltaic coasts subject to heavy anthropogenic activities for prioritized engineering interventions.

Resistivity Characterization of Aquifer in Coastal Semiarid Areas: An Approach for Hydrogeological Evaluation

The Handbook of Environmental Chemistry, 2018

In coastal and semiarid regions, the scientific interest lies in imaging the saltwater intrusion ... more In coastal and semiarid regions, the scientific interest lies in imaging the saltwater intrusion and delineating freshwater aquifer zones, respectively. Direct current resistivity (DCR) and induced polarization (IP) geophysical methods are commonly used to assess hydraulic characteristics of the aquifer. Particularly, the main reason for hydrogeophysical application of both DCR and IP is that the electrical characteristics of aquifers depend mainly on the geometry of the pore space and the porosity controlling the soil and rock effective transport properties. For preliminary hydrogeological investigations, these methods are applied at a wide range of field and laboratory scales. Accordingly, the vulnerable zone to the saltwater intrusion and/or contamination can be characterized by high accuracy. Furthermore, empirical and semiempirical relationships are widely used to predict the aquifer petrophysical characteristics, e.g., hydraulic conductivity, using the inversion results of such electrical methods. Equally, conventional and nonconventional DCR inversion algorithms are developed to reduce the nonuniqueness problem of actual resistivity interpretation and, consequently, to obtain more meaningful models than previously reported. As case histories, this chapter demonstrates the efficiency of DCR method for hydrogeological assessment in Nile Delta, Egypt, emphasizing on technical constraints to achieve sustainable development in coastal and semiarid areas.

Modeling Flash Floods and Induced Recharge into Alluvial Aquifers Using Multi-Temporal Remote Sensing and Electrical Resistivity Imaging

Sustainability, 2020

Flash flood hazard assessments, mitigation measures, and water harvesting efforts in desert envir... more Flash flood hazard assessments, mitigation measures, and water harvesting efforts in desert environments are often challenged by data scarcity on the basin scale. The present study, using the Wadi Atfeh catchment as a test site, integrates remote sensing datasets with field and geoelectrical measurements to assess flash flood hazards, suggest mitigation measures, and to examine the recharge to the alluvium aquifer. The estimated peak discharge of the 13 March 2020 flood event was 97 m3/h, which exceeded the capacity of the culverts beneath the Eastern Military Highway (64 m3/h), and a new dam was suggested, where 75% of the catchment could be controlled. The monitoring of water infiltration into the alluvium aquifer using time-lapse electrical resistivity measurements along a fixed profile showed a limited connection between the wetted surficial sediments and the water table. Throughflow is probably the main source of recharge to the aquifer rather than vertical infiltration at the ...

An integrated approach of GIS and geoelectrical techniques for wastewater leakage investigations: Active constraint balancing and genetic algorithms application

Journal of Applied Geophysics, 2020

Abstract Wastewater leakage problem associated with sewage treatment plants deterioration has bec... more Abstract Wastewater leakage problem associated with sewage treatment plants deterioration has become prominent. We develop and apply procedures of GIS and direct current resistivity (DCR) techniques to investigate the wastewater seepage appearance in a semiarid urban environment. In the first stage, all surface geological and structural information is manipulated using GIS to produce geomorphological and geological maps. Waterlogged sites resulting in land degradation are distinguished by monitoring land-use/land-cover (LU/LC) changes. In the second stage, the DCR method has been performed to characterize the subsurface layer distributions and structures considering the results of GIS and LU/LC mapping data. Because the geophysical inverse problem is usually ill-posed, the active constrain balancing (ACB) approach and genetic algorithms (GA) are applied to optimize the inversion results. In the presence of high conductive layers, the limitation of DCR imaging in detecting the subsurface structure is demonstrated from the synthetic data. Moreover, we demonstrate that the joint use of GA with structure-based model (SBM) is helpful in recognition of subsurface layer distributions with non-smooth interfaces. However, ACB approach is more practical for lateral heterogeneities determination within the same rock unit than SBM with GA approach. The results indicate that the waterlogged areas and wastewater migration pathways are mainly controlled by the drainage networks and subsurface structures. Notably, the integrated approach allows us to assess geotechnical problems and to propose a suitable location for wastewater discharge management. Finally, the study can be considered as a scientific basis for desert urbanization and rational urban development planning.

Tracing Holocene channels and landforms of the Nile Delta through integration of early elevation, geophysical, and sediment core data

The Holocene, 2020

Intensification of anthropogenic activities and related processes have altered the morphology of ... more Intensification of anthropogenic activities and related processes have altered the morphology of modern deltaic systems. As a result, mapping of geomorphic features, such as paleochannels, using recently acquired digital elevation data has become increasingly difficult. Using the Nile River and delta as a test site, we developed and applied procedures to map the distribution of paleochannels that existed throughout the Holocene. A high-resolution digital elevation model (DEM) derived from an early, detailed topographic sheet collection was used to minimize the impact of recent man-made topographic artifacts. The DEM-inferred paleochannel distribution was verified using direct and indirect subsurface data. Using our adopted methodology, we identified 76 main and subsidiary paleochannels with a total length exceeding (by >500 km) previously mapped paleochannels. The overwhelming majority (>80%) of the reported historical and archeological sites (29 sites) in the Nile Delta were ...

Imaging of wastewater percolation in heterogeneous soil using electrical resistivity tomography (ERT): a case study at east of Tenth of Ramadan City, Egypt

Environmental Earth Sciences, 2017

Abstract The objective of this study is to evaluate the effectiveness of DC resistivity surveys f... more Abstract The objective of this study is to evaluate the effectiveness of DC resistivity surveys for imaging the wastewater percolation around the stabilization ponds in the Tenth of Ramadan City, the desert fringes of East Nile Delta, Egypt. Detailed resistivity surveys, including DC soundings and electrical resistivity tomography (ERT), were carried out along several profiles. Furthermore, synthetic modeling of ERT was designed to optimize the survey configurations and interpretation of the results. A 2D modeling of smoothness-constrained least-squares inversion scheme was applied to delineate the possible wastewater infiltration zones from oxidation ponds. Because the geoelectrical interpretation has a degree of non-uniqueness, the resistivity inversion was constrained using borehole lithological information and soil sample laboratory measurements. The DC inversion results indicate decreasing resistivity down to a depth of 15 m around waste disposal sites. The inferred soil zone close to the oxidation ponds was a mixture of sand, silt and clay. Moreover, the clay minerals were characterized by moderate swelling that could have reduced the vertical infiltration speed, causing wastewater seepage, especially around unlined disposal sites and open surface drains. Accordingly, the medium-to-low resistivity values can be attributed to wastewater leakage in clayey sand soil. Because the area slopes generally toward the northeast, the surface seepage was dominant in the shallow impermeable sandy clay subsoil. Therefore, measuring soil parameters is a complementary method to optimize resistivity interpretation, with potential for mitigating environmental hazards from wastewater leakage around disposal ponds.

Internal structural architecture of a soft-linkage transfer zone using outcrop and DC resistivity data: Implications for preliminary engineering assessment

Engineering Geology, 2018

Abstract The current study presents a new integrative approach for detailed structural mapping of... more Abstract The current study presents a new integrative approach for detailed structural mapping of a soft-linkage transfer zone using outcrop, boreholes and DCR data in the form of soundings and 2D-electrical resistivity tomography (2D-ERT). As a case study, the present approach is implied for studying the geo-engineering conditions of a highly deformed desert-land entry to reclaim at Cairo-Suez district, Egypt. The approach has led to the spatial understanding of the subsurface heterogeneity and complex structures at a level of accuracy unattainable with traditional surface structural mapping alone. For preliminary geotechnical assessment, some physical and geotechnical properties are characterized by field and laboratory measurements for collected soil samples. Moreover, the inverted DCR data are used to predict the RQD values using a polynomial relationship between RQD and the intrinsic resistivity (ρ). Notably, the calculated and actual values of RQD are, in general, in the same order considering the error factor value, and hence, the derived equation for RQD prediction is satisfactory. Therefore, the proposed approach reduces the uncertainty of the constructed structural model for engineering design. In addition, merging outcrop with DCR data allows us with a limited frame of time to partially mitigate disasters to civilization by better (i) potential location understanding and (ii) remediation plans tuning for a complex structured site.

Flash floods and groundwater evaluation for the non-gauged dryland catchment using remote sensing, GIS and DC resistivity data: A case study from the Eastern Desert of Egypt

Journal of African Earth Sciences, 2019

Abstract The coastal and alluvial areas of the Red Sea Mountains are mainly being developed for r... more Abstract The coastal and alluvial areas of the Red Sea Mountains are mainly being developed for resorts and tourism activities. Given the development of occasional flash floods in the central part of the Red Sea area can be of destructive consequences to the various anthropogenic activities; thus the quantitative and qualitative assessments of the hydrological parameters and groundwater occurrence are presented. As a case study, Wadi Isl at the Red Sea coast has been hydrogeologically analyzed using an integrative approach of remote sensing, GIS and direct current resistivity (DCR) tools. The time area-zones have been estimated using and Manning's equation into the spatial analyses routines embedded within the ArcGIS. In this study, a synthetic effective rainfall of 10 mm has been applied to compute the spatially distributed runoff hydrograph. The estimated total runoff volume is approximately 8 million cubic meters, and the peak discharge rate is estimated to 163 cubic meters per second, which can be destructive to the main infrastructures in the flash flood pathways. Then, the 2D-electrical resistivity tomography (2D-ERT) surveys have been carried out at various localities along the main wadi course to explore the lateral and vertical variation of alluvium thickness and the saturated zones. Notably, the groundwater occurrence is contained in the structurally controlled graben. Therefore, the study has recommended the construction a main barrier at a natural deep gorge of the main outlet in order to fully control the flash floods and to enhance the potential recharge to the underlying alluvium aquifer. The present integrative approach of both surface and subsurface data is definitely needed to maximize the flash flood benefits.

An integrative approach for preliminary environmental engineering investigations amidst reclaiming desert-land: a case study at East Nile Delta, Egypt

Environmental Earth Sciences, 2017

Scientific interest within the desert-lands lies on mapping the near-surface clayey soils being m... more Scientific interest within the desert-lands lies on mapping the near-surface clayey soils being made environmental engineering problems, e.g., water logging and cracked pavements. As a starting point used for urban rational development, boreholes, direct current resistivity (DCR) soundings and electrical resistivity tomography surveys and preliminary geotechnical studies are employed in an integrative approach for mapping and characterizing the foundation soil. This study is carried out at one of the main urban reclamation projects amidst desert fringes of East Nile Delta, Egypt, as a case study, where the in situ soil properties are variable even within a short distance and, consequently, difficult to be predicted. Conventional and non-conventional inversion approaches are applied for solving the inverse problems of DCR data. The results are calibrated with the drilled borehole lithology. Two main geoelectrical resistivity layers are distinguished: the upper medium to high-resistivity soils corresponding to surface poorly graded sand with gravels underlain by low-resistivity layer attributing to clayey sand with calcareous materials. The inversion results show the sequential joint use efficiency of the two approaches in mapping the near-surface layer boundaries providing realistic soil heterogeneities tomography. In respect of such results and from an engineering point of view, the exaggerated clayey soils are highly saturated in some places representing (1) medium plasticity, moderate-to-high swelling and (2) low compressive strength. It is conceivable that such soils can exhibit geotechnical problems, especially under wetting conditions. Consequently, the integrative approach is cost-effective and opens the way for engineers on where prioritized interventions are required to the urban expansion.

Use of salinity and resistivity measurements to study the coastal aquifer salinization in a semi-arid region: a case study in northeast Nile Delta, Egypt

Environmental Earth Sciences, 2016

To understand the impact of sea level rise (SLR) and aquifer intensive use would cause to the gro... more To understand the impact of sea level rise (SLR) and aquifer intensive use would cause to the groundwater level and saltwater intrusion, an integrated relationship between salinity and electrical resistivity of a Quaternary aquifer is established in the northern part of East Nile Delta (El Sharkia area), Egypt. Historical data of groundwater salinity are mapped and compared with the current water samples to better understand the salinity spatial variability. The salinity maps show that salinization has increased sustainably. Additionally, the transition/dynamic zone related to SLR and/or excessive pumping can be addressed. In particular, the surface DC resistivity soundings were carried out to demonstrate the vertical and horizontal salinity distributions in the area. In the course of this study, the 1D model generation using a hybrid genetic algorithm (GA) was applied and tested using borehole information. The constructed geoeletrical cross-sections emphasize and delineate the extension of saltwater intrusion. Cleary, it is found that due to excessive pumping from shallow wells over the last decades, the subsurface resistivity and TDS vertical distributions can change rapidly within a short distance. Additionally, the results show that despite the dominance of brackish and saltwater at the northern part of the area, perched low conductive lenses are observed reflecting a low level of groundwater salinization. To obtain a link between water salinity and aquifer resistivity, an empirical relationship was derived to predict the salinity variations at different depths. In comparison with the measured total dissolved solids (TDS), the predicted salinity map appears realistic. These results demonstrate the important role of the integration between resistivity and salinity measurements for mapping the groundwater salinization with depth, and call for further research to plan and manage the area's water resources.

Assessment of oxidation ponds impact using DC resistivity method in Tenth of Ramadan city, Egypt

A large quantity of wastewater is collected in three oxidation ponds raising serious environmenta... more A large quantity of wastewater is collected in three oxidation ponds raising serious environmental concern in the east of Tenth of Ramadan city, Egypt. In the present work, the DC resistivity method in the form of 1D and 2D was applied for wastewater percolation monitoring in the area around the oxidation ponds. The resistivity measurements were integrated with laboratory studies of soil samples to estimate grain size, porosity, clay contents and degree of saturation. According to the former Schlumberge sounding survey, six 2D resistivity profiles were measured closed to the ponds. Wenner beta and Pole-dipole electrode arrays were selected for 2D resistivity imaging based on a prior synthetic modelling. The 1D model generation and verification by the use of genetic algorithms (GA) represent an accurate quick solution to the subsurface resistivity layer distributions. A conventional derivative-based inversion with cell-model provides valuable constraints to interpret the 2D resistivi...

Electrical Methods: Practical Guide for Resistivity Imaging and Hydrogeophysics

This book constitutes an encouraging example using electrical methods (DC, FDEM and SIP) in chara... more This book constitutes an encouraging example using electrical methods (DC, FDEM and SIP) in characterizing the coastal aquifer. The geophysical inversion results are represented in form of 1D, 2D and 3D imaging. Both DC sensitivity analysis and synthetic modeling are discussed in details. In addition, the joint inversion of different arrays is assessed to improve the model reliability especially under no or limited prior geological information. The intention here also is to establish an empirical relationship between the aquifer resistivity and the aquifer hydraulic parameters using the DC soundings. Published data from Nigeria and India is used to establish this equation. In Germany, DC soundings and 2D SIP data was used to investigate the hydrogeophysical conditions of tidal deposits. This book provides a ‘crash course’ in the new frontiers of environmental and hydrogeophysics.

Application of genetic algorithm (GA) for soil characterization using DC resistivity data: A case study in Tenth of Ramadan city, Egypt

Advances in Natural and Applied Sciences

Resistivity Characterization of Aquifer in Coastal Semiarid Areas: An Approach for Hydrogeological Evaluation

Part of the The Handbook of Environmental Chemistry book series, 2018

In coastal and semi-arid regions, the scientific interest lies in imaging the saltwater intrusion... more In coastal and semi-arid regions, the scientific interest lies in imaging the saltwater intrusion and delineating freshwater aquifer zones, respectively. Direct current resistivity (DCR) and induced polarization (IP) geophysical methods are commonly used to assess hydraulic characteristics of the aquifer. Particularly, the main reason for hydrogeophyical application of both DCR and IP is that the electrical characteristics of aquifers depend mainly on the geometry of the pore space and the porosity controlling the soil and rock effective transport properties. For preliminary hydrogeological investigations, these methods are applied at a wide range of field and laboratory scales. Accordingly, the vulnerable zone to the saltwater intrusion and/or contamination can be characterized by high accuracy. Furthermore, empirical and semi-empirical relationships are widely used to predict the aquifer petrophysical characteristics, e.g. hydraulic conductivity, using the inversion results of such electrical methods. Equally, conventional and non-conventional DCR inversion algorithms are developed to reduce the non-uniqueness problem of actual resistivity interpretation and, consequently, to obtain more meaningful models than previously reported. As case histories, this chapter demonstrates the efficiency of DCR method for hydrogeological assessment in Nile Delta, Egypt, with emphasizing on technical constraints to achieve sustainable development in coastal and semi-arid areas.

Electrical Methods: Practical Guide for Resistivity Imaging and Hydrogeophysics

This book constitutes an encouraging example using electrical methods (DC, FDEM and SIP) in chara... more This book constitutes an encouraging example using electrical methods (DC, FDEM and SIP) in characterizing the coastal aquifer. The geophysical inversion results are represented in form of 1D, 2D and 3D imaging. Both DC sensitivity analysis and synthetic modeling are discussed in details. In addition, the joint inversion of different arrays is assessed to improve the model reliability especially under no or limited prior geological information. The intention here also is to establish an empirical relationship between the aquifer resistivity and the aquifer hydraulic parameters using the DC soundings.

Induced polarization response of organic-rich soil at the field scale: Case histories

Monitoring of saltwater intrusion using resistivity and salinity measurements in the northern part of El-Sharkia area, Egypt

The impacts would be very serious: Sea level rise would change the water quality.

Use of DC and FDEM methods to image the Quaternary aquifer and saltwater at Lüdingworth, Cuxhaven area, Germany

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Characterization of Holocene Near Surface Geology Using DC, FDEM and SIP Methods, Cuxhaven Area, Germany

The Use of Induced Polarization for Detecting The Hydraulic Characteristics-The Shillerslage Case Study

Fig. 1: (left) Location map of Schillerslage test site, available borehole, SIP field measurement... more

On the use of DC resistivity soundings for characterizing the hydrogeological conditions in semi-arid region-the East of Nile Delta Egypt

1 10 100 r 2 = 0.99 Slope= 4.5 Slope= 2.3 r 2 = 0.9

Prediction of permeaability anisotropy using Dar-Zarrouk parameters of deep resistivity logs: a case study in the Northern Western desert of Egypt.

4 Theory 5 Results and Discussion 6 Conclusions 7 Motivation 8th International Sympousium on Geop... more 4 Theory 5 Results and Discussion 6 Conclusions 7 Motivation 8th International Sympousium on Geophysics (ISG-8 ) 3/23 Mohamed Attwa Problem  Currently, most petrophysical parameters are determined from ex situ samples taken from boreholes.  The laboratory examination of core samples is rather expensive as well as time consuming.

Geoelectrical and Geotechnical Investigations at Tenth of Ramadan City, Egypt - A Structure- Based (SB) Model Application

1D and 2D DC inversions for environmental investigation around oxidation ponds

Questions bank.docx

for my students

EM practical sheets

1-Calculate the depth of penetration of electromagnetic fields with frequencies of 10, 500, and 2... more

Very-low Frequency (VLF

Fundamentals The very-low frequency (VLF) electromagnetic method detects electrical conductors by... more Fundamentals The very-low frequency (VLF) electromagnetic method detects electrical conductors by utilizing radio signals in the 15 to 30 kiloHertz (kHz) range that are used for military communications. The VLF method is useful for detecting long, straight electrical conductors, such as moderate to steeply dipping water-filled fractures or faults. The VLF instrument compares the magnetic field of the primary (transmitted) signal to that of the secondary signal

EM practical sheets

1-Calculate the depth of penetration of electromagnetic fields with frequencies of 10, 500, and 2... more

Principles of geoelectrical methods

definitions.docx

Tutorial : 2-D and 3-D electrical imaging surveys

Potential Theory in Applied Geophysics

IP lecture.docx

which may be written as

Analytical continuation/Numerical methods

hydrochemistry 4th lect. saltwater intrusion

Netherlands -River the average rainfall of the entire month. Air, sea and rail transport have bee... more

midterm hydrogeology exam 2015

Hydrogeology 3rd lecture

hydrochemistry 3rd lecture

Ground water quality criteria" means the designated levels or concentrations of constituents that... more Ground water quality criteria" means the designated levels or concentrations of constituents that, when exceeded, will prohibit or significantly impair a designated use of water. Groundwater quality comprises the physical, chemical, and biological qualities of ground water. Temperature, turbidity, color, taste, and odor make up the list of physical water quality parameters.

Hydrochemistry 2nd lecture

Hydrogeology 2nd lect.

Hydrogeochemistry lect.

hydrogeology 1st lecture

2nd lecture-Running water-1st geology

Waterways erode, transport, and deposit rock and sediment to produce landforms such as canyons, v... more

2nd lecture-groundwater-1st geology

Groundwater is an important source of freshwater for agriculture, industry, and domestic use.

audislide presenation