Total Longitudinal Conductance Research Articles

Vulnerability Assessment of Groundwater to Contamination Using Electrical Resistivity Method at the Open Dumpsite in Gosa, Abuja, Nigeria

Electrical resistivity method was used to investigate the open dumpsite at Gosa, Abuja in order to determine the vulnerability of the groundwater in the area as well as the surrounding environment to leachate contamination. A total of sixteen (16) vertical electrical sounding points with maximum current electrode of 100 m were investigated. The data were analyzed and used to establish the parameters required to fulfil the objectives of this research. A maximum of four geoelectric sections were identified in the area. They included sandy topsoil, clayey sand, weathered basement and fractured/fresh basement. Apparent resistivity values obtained for the four layers delineated were between 64.6 Ωm and 215.5 Ωm for the first layer; 19.0 Ωm and 295.6 Ωm for the second layer; 66.9 Ωm and 1003.7 Ωm for the third layer; and 438.0 Ωm and 1719.9 Ωm for the fourth layer. Furthermore, the ranges of the thickness of the layers were found to be 0.7 m and 12.9 m for the first layer; 1.3 m and 9.8 m for the second layer; and 1.6 m and 11.6 m for the third layer. The depths of water table in the area were estimated to range between 2.1 and 21.6 m. The parameters used in characterizing the aquifer protective capacity of the overburden units were layer thickness and their corresponding resistivity values. Accordingly, the total longitudinal layer conductance of the overburden of the area was generally found to be low, ranging between 0.014 mhos and 0.063 mhos, implying that the aquifer protective capacity of the area is poor. The 1D resistivity cross section for the three profiles investigated exposed the movement of contaminants toward the aquifer, further validating the fact that the aquifer is not protected. The low protective capacity of the area aided the conclusion that the water aquifer in the area was highly vulnerable to leachate contamination from the dumpsite.

Groundwater vulnerability assessment using hydrogeologic and geoelectric layer susceptibility indexing at Igbara Oke, Southwestern Nigeria

Groundwater vulnerability assessment was carried out at Igbara Oke Southwestern Nigeria, with a view to classify the area into vulnerability zones, by applying the electrical resistivity method, using Schlumberger electrode arrays with maximum electrode separation (AB/2) of 65m in (41) different locations for data acquisition. Geoelectric parameters (layer resistivity and thickness) were determined from the interpreted data. The study area comprises four geoelectric layers (topsoil, lateritic layer, weathered/fractured layer and fresh basement). The geoelectric parameters of the overlying layers across the area were used to assess the vulnerability of the underlying aquifers to near-surface contaminants with the aid of vulnerability maps generated. Three models were compared by maps using geo-electrically derived models; longitudinal conductance, GOD (groundwater occurrence, overlying lithology and depth to the aquifer) and GLSI (geoelectric layer susceptibility indexing). The total longitudinal conductance map shows the north central part of the study area as a weakly protected (0.1–0.19) area, while the northern and southern parts have poor protective capacity (<0.1); this is in agreement with the GOD method which shows the northern part of the study area as less vulnerable (0–0.1) while the southern part has low/moderate (0.1–0.3) vulnerability to contamination. The longitudinal conductance exaggerates the degree of susceptibility to contamination than the GOD and GLSI models. From the models, vulnerability to contamination can be considered higher at the southern part than the northern part and therefore, sources of contamination like septic tank, refuse dump should be cited far from groundwater development area.

Role of Groundwater Protection Planning in Groundwater Governance: A Case Study from North India

Abstract: In the present case study, impact of urbanization and industrial development on the shallow groundwater regime of Saharanpur town of Uttar Pradesh in India is examined with the aim of planning groundwater protection for better governance. The hazardous physicochemical and bacteriological parameters and heavy metals detected in the shallow aquifer include harmful pathogens like fecal coliforms, heavy metals like cadmium, chromium, nitrates and sulphates. An assessment of ground water vulnerability using the well known DRASTIC method has confirmed that the shallow groundwater in some central and southern localities of Saharanpur town fall in the medium risk zones. Further, using field data of 32 electrical resistivity soundings, the protective capacity of the unconfined aquifer is assessed in terms of a ‘total longitudinal conductance’ of the semi-pervious to impervious sediments overlying the unconfined aquifer. However, some areas aligned along a northwest-southeast and in the western parts of the town seem to have relatively higher protective capacity against infiltrating waste pollutants. A ground water protection planning map prepared by combining the DRASTIC map and the ‘potentially hazardous pollutants’ map has brought out the need to install eleven new groundwater quality monitoring wells in the town at locations near the line sources and point sources of pollution. This approach can be readily employed by the decision makers in framing sound guidelines for groundwater protection and governance.

Карта суммарной продольной проводимости осадочного чехла Центральной Украины

Карта суммарной продольной проводимости осадочного чехла Центральной Украины

Карта суммарной продольной проводимости осадочного чехла Днепровско-Донецкой впадины и Донбасса

Карта суммарной продольной проводимости осадочного чехла Днепровско-Донецкой впадины и Донбасса

On the Carpathian electrical conductivity anomaly depth study

Carpathian electrical conductivity anomaly (CECA) was discovered in the 1960ies and intensively studied by both individual institutions and within the framework of international projects in many countries, but without any strategic plan, which should be based on the definition of research objective, abilities of used methods (MVP and MTS) and rules of their interaction. The paper presents the main results of CECA research: construction of induction vectors in more than 1000 points, putting the anomaly on map, estimation by MVP methods of maximum possible depth of anomalous currents center and total longitudinal conductance of anomalous body. True depth of anomaly upper edge was defined by MTS method only in three localities and the works were performed 25-40 years ago. Goal of future CECA researches should be study of its nature (fluids or electronically conducting minerals) and prospects of practical use (minerals, geothermal energy ...). The first step in this direction should be MTS fulfillment (and/or other soundings) over the axis of the CECA to select locations for drilling.

Geohydrological investigation using Schlumberger sounding in part of hard rock and alluvial area of Ahraura region, Mirzapur district, Uttar Pradesh, India

The study area is located in the part of hard rock and alluvial area of Ahraura region, Mirzapur district, Uttar Pradesh, India. Twenty-two vertical electrical soundings (VES) were conducted using Schlumberger configuration at suitable locations in study area for geohydrological or groundwater investigation. The VES data were interpreted using both techniques: curve matching technique and automatic iterative method. Geoelectrical cross section along the five profiles was conducted based on the results of vertical electrical soundings using Schlumberger configuration. A priori information, detailed survey, and appropriate locations of vertical electrical sounding were done using satellite imagery and integrated geophysical methods. The different types of hydro-resistivity maps are prepared based on the results of VES such as contour map of total transverse resistance and total longitudinal conductance, 3-D surface map of total transverse resistance and total longitudinal conductance, contour map of substratum, and one-grid vector resistant substratum map, giving the information about lithological changes and subsurface geology.

Geo-electrical Method Applied to Evaluation of Groundwater Potential and Aquifer Protective Capacity of Overburden Units

Aims: This study was designed to determine different subsurface Geo-electric layers, the aquifer units, determination of Dar-Zarrouk parameter (Longitudinal conductance(S) and Transverse resistance (R)) as well as identifying suitable areas with poor, weak, moderate and excellent aquifer protective capacity rating. Study Design: The study area, Sabo in Kaduna state lies approximately between latitudes 10o25’N and 10o30’N and longitudes 7o25’E and 78o30’E covering an area of about 500,000m. Methodology: A total of sixty-six (66) vertical electrical soundings (VES) using Schlumberger electrode array were acquired with a maximum electrode separation of AB/2=100 m, using the ABEM Terrameter SAS 300C. Results: Maximum of five lithologies were identified namely, topmost layer which consists of lateritic clay, river sand and gravel, clayey sand, weathered transition zone/ fractured layer and the fresh basement. Qualitative interpretation indicates that the weathered layer and weathered/fractured basement constitutes the main aquifer units. These aquifers are characterized by thick overburden found within basement depressions with maximum value of 65 m and resistivity values between 10 ohm.m and 756 ohm.m. Original Research Article British Journal of Applied Science & Technology, 4(14): 2024-2037, 2014 2025 The Dar-Zarrouk parameters evaluated are total longitudinal unit conductance (S) and total transverse resistance (T) with values ranging from 0.005 – 0.65 mhos and 2000 – 32000 ohm.m. Conclusion: The results show that the lithology of the aquifer is dominated by clay/clayey sand and sandy materials with attendant low and high transmissivity. About 80 % of the area has longitudinal conductance value greater than 0.3 mhos due to high content of clay/lateritic clay indicating moderate protective capacity rating, hence vulnerable to contamination.

Aquifer Vulnerability Investigation Using Geoelectric Method in Parts of Sapele Local Government Area of Delta State, Nigeria

The electrical resistivity survey has been used in the determination of the overburden protective capacity in Amukpe area of Delta State, Nigeria. Nineteen Schlumberger vertical electrical soundings (VES) were carried out with maximum electrode separation of 1000m. The data were presented as VES curves interpreted quantitatively by computer iteration using the Resist Software to obtain the first order geoelectric parameters. Three geoelectric layers namely the topsoil, laterite/clayey sand and sand (medium to coarse grained) were delineated from the survey. The topsoil has resistivity values ranging from 43 to 1067m and thickness varying from 0.8 to 1.6 m. The second geoelectric layer is composed of clayey sand and laterite with resistivity values ranging from 77 to 644 m and thickness varying from 3.8 to 6.7 m. While the third geoelectric layer represents the aquiferous unit with resistivity values ranging from 200 to 1067 m diagnostic of sand (fine to coarse grained). The interpreted geoelectric data correlated with lithologic logs of a borehole drilled in the study area. The overburden protective capacity in an area was evaluated by utilizing the total longitudinal unit conductance values. The generated longitudinal conductance map showed poor protective capacity (

The estimation and significance of Dar-Zarrouk parameters in the exploration of quality affecting the Gulf of Aqaba coastal aquifer systems

The subsurface resistivity layer parameters of 47 vertical geoelectrical soundings are analyzed for a rectangle shaped area of 70 km2 from the Gulf of Aqaba coast. For this purpose, the Dar-Zarrouk parameters i.e., (i) total longitudinal unit conductance, (ii) total transverse unit resistance and (iii) average longitudinal resistivity are used to determine the resistivity regime of the water bearing formations. The significance of these parameters is to establish a vision about the occurrence and distribution of water bodies, while dealing with complicated situations of resistivity ranges intermixing for saline, brackish and fresh water aquifers. The results obtained from the study area suggest that the Dar-Zarrouk parameters proved useful in providing confident solution to delineate water-bearing formations. The behavior of the Dar-Zarrouk parameters and its patterns in space over large areas with respect to the occurrence of water aquifer systems in the deltaic coastal area has been demonstrated.

The experience of two-dimensional magnetovariance modeling in the area of UAAS "Academician Vernadsky" (West Antarctic Peninsula)

For the first time for the waters of the Antarctic Peninsula, quantitative assessment of the distribution of geoelectric parameters of sea water, both in space and depth, as well as of a layer of sediment presumably of Cenozoic era, lying directly under the water has been given. This layer according to the seismic method of reflected waves is widespread in the continental shelf waters. Availability under the top layer of the older sedimentary rocks is still quite unknown. According to seismic and geo-electric methods at the present level of knowledge the existence of such sediments is expected both in shelf zone of the Bellingshausen Sea, and in the Larsen sedimentary basin. Based on the estimates of geoelectric parameters a map of the total longitudinal conductivity of sedimentary cover of M 1 : 10 000 000 of the region has been compiled for the first time. Magnetovariational parameters on the profile, crossing the Antarctic archipelago of islands have been given, which have shown that the conductive structures, which determine their behavior have a strike, coinciding with the strike of isobaths. To determine the capacity of geoelectrical methods for studying the deep structure of the region calculations have been made of interpretational parameters of magnetotelluric field by numerical simulation of twodimensional model along the profile of the valley of the Bellingshausen Sea to the kettle of the Weddell Sea, in which the distribution of geoelectric parameters of the sedimentary cover has been specified with the highest adequacy. Calculations have shown that the observed experimental data do not completely satisfy the model calculations. This fact gives grounds to hope that at least in the areas adjacent to Graham Land, geoelectrical investigations will facilitate studies of the deep structure of the regions.

Longitudinal conductivity of layered charge-ordered crystals in a high quantizing magnetic field

The longitudinal conductivity of layered charge-ordered crystals in a high quantizing magnetic field perpendicular to layers is determined. The conditions in which the order parameter and chemical potential of carriers are oscillatory functions of the magnetic induction B are considered. The longitudinal conductivity is calculated for two relaxation time models: the time proportional to the longitudinal carrier velocity and constant time. It is shown that the relative contribution of the oscillatory conductivity part in the former model is less than in the latter. In high magnetic fields, the total conductivity of the layered crystal in the case of the relaxation time proportional to the longitudinal velocity initially exceeds the total longitudinal conductivity for the case of the constant relaxation time. However, in very high magnetic fields under conditions of carrier concentration in the single occupied Landau subband, the total conductivity in the case of the relaxation time proportional to the longitudinal velocity is again less than in the case of the constant relaxation time. Under these conditions, at a constant relaxation time, the total conductivity tends to zero as σ zz ∝ B −2; at the relaxation time proportional to the longitudinal velocity, it tends to zero as σ zz ∝ B −3.

Influence of topological transitions in a quantizing magnetic field and anisotropy of current carrier scattering by acoustic phonons on the longitudinal electrical conductivity of layered crystals with open fermi surfaces

It is demonstrated that the dependence of Fermi’s energy on the magnetic field causes a set of the Shubnikov – de Haas (SDH) oscillation frequencies to change, and their relative contribution to the total longitudinal conductivity of layered crystals depends on whether the scattering of current carriers is isotropic or anisotropic. Owing to the topological transition in a strong magnetic field, Fermi’s surface (FS) is transformed from open into closed one and is compressed in the magnetic field direction. Therefore, in an ultraquantum limit, disregarding the Dingle factor, the longitudinal electrical conductivity of the layered crystal tends to zero as a reciprocal square of the magnetic field for the isotropic scattering and as a reciprocal cube of the magnetic field for the anisotropic scattering. All calculations are performed in the approximation of relaxation time considered to be constant versus the quantum numbers for the isotropic scattering and proportional to the longitudinal velocity of current carriers for the anisotropic scattering.

Electromagnetic soundings of the sedimentary cover and consolidated crust in the transition zone from the Moscow syneclise to the Voronezh anteclise: Problems and prospects

The methods and results of electromagnetic soundings (EMS) performed in the transition zone from the Moscow syneclise to the Voronezh anteclise in the vicinity of the MSU geophysical base are considered. This base is located in the village of Aleksandrovka in the Yukhnov district of Kaluga area. The composite EMS curves characterizing rock complexes composing the sedimentary cover are constructed, and changes in these complexes within the specified transition zone are traced. The standard curves of magnetotelluric (MT) and magnetovariational (MV) soundings are constructed from the results of long-term measurements at the ALX observation point located at the Moscow State University’s (MSU) geophysical base. The maps of thickness and total longitudinal conductance of the sedimentary cover are constructed from the results of interpretation of MT data obtained in the region. A conductor in the consolidated Earth’s crust is identified within the Voronezh anteclise. Prospects for further investigations of the region are associated with the tracing of the crustal conductor within the Voronezh anteclise, as well as with the organization of an observatory at the MSU’s geophysical base in order to perform long-term measurements of the electromagnetic (EM) and other geophysical fields.

Geoelectric parameters of the earth's crust of the western part of the Ukrainian shield according to the one-dimensional inversion of magnetotelluric soundings

On the basis of one-dimensional inversion of MTS curves on the most part of the Volynsk and the western part of the Podolsk mega-blocks in a "granite" layer the objects of the lowered resistance (OLR) have been selected which at the present stage of researches are difficult for uniting in a uniform conductive layer. In a transitive layer it is possible to assume the presence of a conductive horizon (with prevailing values of total longitudinal conductivity more than 100 S), in which the places with "holes" are available (i. e. areas of absence OLR). On the most part of the investigated territory the total longitudinal conductivity of rocks with thickness of about 30-35 km basically does not exceed 250 S. Correlation of the area of distribution of conductive objects with graphitic rock by areas allows assumption, that the lowered resistance in these areas is explained by graphitization of rocks composing both "granite" and a part of transitive layer. Active at the present stage of development lineament zones - the Ustlugsko- Malinskaya, Yavorovsko-Volchansk (comprising the northern part of the Dnipro-Labe zone) and the Mukachevo-Dnepropetrovsk - zone are accompanied by conductive objects located at various depths.

The structure of the tectonosphere of the Urals and West Siberian Platform by electromagnetic data

Advances in magnetotelluric sounding (MTS) have provided the possibility to study deep parts of the planet and obtaining information on electroconductivity of the Earth’s tectonosphere, which is very sensitive to the lithology of rocks in the upper part of the crust, as well as to the phase state of substance, the temperature, concentration, and mineralization of fluids. Introduction of modern broadband digital measuring and computation equipment, as well as programs of computational modeling allowed us to realize more completely the possibilities of geoelectric methods. The technical approach including the integration of geoelectric methods, the processing of experimental materials, and interpretation of data with construction of geoelectric models of the medium was considered in detail by the example of geotraverses through the Northern and Southern Urals [1, 2]. The material on the study of fields of natural sources of geomagnetic variations of the ionospheric and magnetospheric origin (AMT‐MTS‐DMTS methods) and the induction electromagnetic sounding (IEMS) method with a controlled source along a traverse about 1000 km long from the Settlement of Askino (Bashkortostan) in the west to Tyukalinsk (Omsk oblast) in the east with an a posteriori test of the previously obtained results [3] was generalized for the first time in this work; the geotraverse partially coincides with the Sverdlovsk profile of deep seismic sounding (DSS). In this case, major faults and zones of higher fracturing in the crust, as well as relationships between electroconductivity and the tectonic structure of regions, were studied. The originality of the studies performed lies in the fact that peculiarities of tectonosphere stratification were traced by electric parameters within a depth from 10 m to 600 km, and traces of events that proceeded there over a large time interval were revealed. The results are presented in Fig. 1. According to the distribution of total longitudinal conductance of the lithosphere ( S ), the territory under consideration can be subdivided into three sectors, the boundaries of which mark zones of abnormally high conductivity, which

Andreev reflection in a mesoscopic hybrid four-terminal Rashba ring

The transport properties of a mesoscopic hybrid four-terminal Rashba ring are investigatedalong the lines of Blonder, Tinkham and Klapwijk and our attention is focused on theinfluence of Andreev reflection. Although the resonant peak and zero conductance resultingfrom spin-dependent quantum interference are destroyed by incoherent addition in thisfour-terminal structure, the total longitudinal electron conductance is still enhanced by theAndreev contribution. However, the contribution of the Andreev reflection to the spinHall conductance in this mesoscopic Rashba ring is negative and the total spinHall conductance is reduced. These results are robust to an external magneticflux.

Photoconductivity in AC-driven modulated two-dimensional electron gas in aperpendicular magnetic field

In this work we study the microwave photoconductivity of a two-dimensionalelectron system (2DES) in the presence of a magnetic field and a two-dimensionalmodulation (2D). The model includes the microwave and Landau contributions ina non-perturbative exact way; the periodic potential is treated perturbatively.The Landau–Floquet states provide a convenient base with respect to which thelattice potential becomes time dependent, inducing transitions between theLandau–Floquet levels. Based on this formalism, we provide a Kubo-like formula thattakes into account the oscillatory Floquet structure of the problem. The totallongitudinal conductivity and resistivity exhibit strong oscillations, determined byϵ = ω/ωc, withω the radiationfrequency and ωc the cyclotron frequency. The oscillations follow a pattern with minima centredat , and maxima centred at , where j = 1,2,3...,δ∼1/5 is a constantshift and l is the dominant multipole contribution. Negative resistance states (NRSs) develop asthe electron mobility and the intensity of the microwave power are increased.These NRSs appear in a narrow window region of values of the lattice parameter(a),around a∼lB, where lB is the magnetic length. It is proposed that these phenomena may be observed inartificially fabricated arrays of periodic scatterers at the interface of ultracleanGaAs /AlxGa1−xAs heterostructures.

Groundwater prospecting and management in an agro-based rural environment of crystalline terrain of India

An integrated hydrogeological investigation was made to delineate the socioeconomic problems in the agro-based rural environment of the crystalline terrain of Guntur district, Andhra Pradesh, India. The integrated investigation comprised geoelectrical (GE) surveys, remotely recorded data and pumping tests. The subsurface layer parameters obtained from the sounding interpretation are presented in the form of GE sections and a fence diagram. Characteristic resistivities of various layers were obtained by correlating the known lithology with the GE sounding data. Total transverse resistance (TTR) and total longitudinal conductance (TLC) were computed from the interpretation of the sounding data. The TTR map was compared with the depth of bedrock map and the values of TLC were correlated with the thickness of geoelectrical layers and water quality. Lineaments were mapped from the satellite imageries. Hydraulic properties were determined, using the standard pumping test analysis. Potentiality of aquifer zones was assessed, after comparing the known thickness of aquifer formations with the corresponding discharge (Q) values. The integrated study helps to evolve a criterion to classify the groundwater potential zones (GPZ) into low, medium and high, based on the thickness of the aquifer zone and its corresponding resistivity, TTR, TLC and Q. A management plan has been proposed for sustainable development of groundwater in the region to eliminate water scarcity and its related problems.

A new method of geoelectrical prospecting by vertical electric current soundings

Some advantages and problems of a new geoelectrical prospecting method, vertical electric current soundings (VECS) are discussed. This method is based on using a new source, circular electric dipole (CED). The source is installed in the following way. One of the transmitter poles is grounded in the central point. The other pole is uniformly grounded around with a radius determined by the depth of investigation desired. It can be defined as a noninductive source. The most interesting CED properties in the low frequency regime are as follows. CED has no magnetic field of its own. It is a pure galvanic source, which differs from a loop (a pure inductive source) and from a line, which is both galvanic and inductive (a ‘line’ here means a cable or insulated wire grounded at its end points). The normal magnetic field on the earth's surface (and above it) of a horizontally layered medium is absent (within the quasi-static approximation), and only a radial electric component exists. A CED field is at right angles to the loop field and has azimuthal symmetry. The CED field is always governed by a vertical medium structure (at the latter transient stage as well) rather than by the total longitudinal conductivity. An interesting result was obtained: in marine electrical prospecting a sea water layer will not play such a crucial role when a CED is used as in applying a loop or a line. In a medium with non-conducting basement the decay of the CED field is exponential. The transient process is more fast than in the case of a loop or a line. The CED can be also considered as a ground analogue of another known source, a vertical electric line. Besides, the CED is a pure galvanic source that does not excite a long-term transient field. Thus it seems to be a new useful means to study IP processes. The mathematical apparatus is represented in the frequency and time domain. The authors consider the results of the initial field tests.