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1.
Our study focuses on the potential usefulness of surface geophysical data to constrain the water content within an alluvial
aquifer. On a study area where two wells have been drilled, we have performed several geophysical measurements, including
ground penetrating radar, DC resistivity prospecting, seismic refraction survey and magnetic resonance soundings. From these
data, we estimated several parameters, namely, the water height in the deposits, the effective porosity, the water content,
the permeability, and the transmissivity of alluvial deposits. These physical parameters allow us to characterize the alluvial
deposits in order to constrain the estimation of the potential water flow. The lithology and water flow rate known from the
wells enabled us to compare geophysical results obtained in a high water flow rate zone to those in a low water flow rate
zone. Correlation has been found between the water flow rate observed in both wells and the geophysical data obtained in the
vicinity of these wells. 相似文献
2.
Geophysical Investigation of Fresh‐Saline Water Interface: A Case Study from South Punjab,Pakistan 
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下载免费PDF全文 The importance of the study of fresh‐saline water incursion cannot be over‐emphasized. Borehole techniques have been widely used, but they are quite expensive, intrusive, and time consuming. The electrical resistivity method has proved very successful in groundwater assessment. This advanced technique uses the calculation of Dar‐Zarrouk (D‐Z) parameters, namely longitudinal unit conductance, transverse unit resistance, and longitudinal resistivity has been employed by using 50 vertical electrical sounding points to assess the groundwater and delineate the fresh‐saline water interface over 1045 km2 area of Khanewal in Southern Punjab of Pakistan. The x‐y plots and maps of D‐Z parameters were produced to establish a decipherable vision for the occurrence and distribution of different water‐bearing formations of fresh‐saline water aquifers through a complicated situation of intermixing of different resistivity ranges for fresh‐saline water bodies. This technique is useful to reduce the ambiguity produced by the process of equivalence and suppression which cause intermixing in differentiating fresh, brackish, and saline aquifers during interpretation. The fresh‐saline water interface is correlated very well with the previous studies of water quality analysis carried out in Khanewal area. The results suggest that the D‐Z parameters are useful for demarcating different aquifer zones. The behavior and pattern of D‐Z parameters with respect to occurrence and distribution of different water‐bearing formations were effectively identified and delineated in the study area. 相似文献
3.
Abstract The resolution of the freshwater and saline water aquifers in a coastal terrain (Mahanadi Basin, India) is updated. We analysed electrical borehole log data at four sites and compared the water resistivity regime of the freshwater and saline water zones obtained from electrical borehole logging, with the resistivity regime obtained by interpreting vertical electrical sounding (VES) data. The multilayer VES data interpretation is modified to a simple model, containing only the freshwater zone and the saline water zone. The composite geophysical parameters of the freshwater and saline water zones, in particular the resistivity and longitudinal unit conductance regime, are identified. The resolution obtained from the composite geophysical data analyses is very clear and convincing. The composite longitudinal unit conductance regime of the saline water zones is very high compared to that of the freshwater zones. This makes the identification of the two aquifers easy and increases its reliability. A technique which enables analysis of composite geophysical data of freshwater and saline water zones at VES sites in the vicinity of the borehole log sites is proposed. The significance of longitudinal unit conductance in resolving the freshwater and saline water aquifers is illustrated graphically. The proposed technique is validated by correlating the longitudinal unit conductance and resistivity with the total dissolved solids. The efficiency of the technique is validated by carrying out discriminant function analysis. Citation Hodlur, G. K., Dhakate, R., Sirisha, T. & Panaskar, D. B. (2010) Resolution of freshwater and saline water aquifers by composite geophysical data analysis methods. Hydrol. Sci. J. 55(3), 414–434. 相似文献
4.
Geophysical methods were applied for hydrogeological targets in many countries including Vietnam. This paper presents results of using complex geophysical techniques as well as 2D electrical resistivity imaging (ERI), vertical electrical sounding (VES), very low frequency (VLF), and seismic refraction for geological structure investigation for locating the aquifers and assessing the hydrogeological conditions for groundwater potential in industrial zones of North Hanoi, Vietnam. The locations of two aquifers are determined by their depth and thickness on the basis of resistivity and seismic velocity values which were proved by stratifications of three boreholes to 40–60 m of depth on the study area. There are connections from surface water to shallow aquifer by hydraulic windows, as follows from VLF data. The deeper aquifer can be considered as a potential groundwater supply, but the water level is descending in time, as shown by hydrological monitoring. However, with careful use and by reducing sources of pollution, groundwater can continue to be an important natural resource for future. 相似文献
5.
Ettore Cardarelli Michele Cercato Antonio Cerreto Gerardina Di Filippo 《Geophysical Prospecting》2010,58(4):685-695
Near‐surface cavities can pose serious hazards to human safety, especially in highly urbanized town centres. The location of subsurface voids, the estimation of their size and the evaluation of the overburden thickness are necessary to assess the risk of collapse. In this study, electrical resistivity tomography (ERT) and seismic refraction tomography data are integrated in a joint interpretation process for cavity location in the city of Rome. ERT is a well established and widely employed method for cavity detection. However, additional information provided by seismic refraction tomography is capable of eliminating some potential pitfalls in resistivity data interpretation. We propose that the structure of the cavities defined by ERT can be used as a base to optimize seismic refraction tomography investigations within the framework of a joint interpretation process. Data integration and the insertion of a priori information are key issues for reducing the uncertainties associated with the inversion process and for optimizing both acquisition procedures and computation time. Herein, the two geophysical methods are tested on both synthetic and real data and the integration of the results is found to be successful in detecting isolated cavities and in assessing their geometrical characteristics. The cavity location inferred by geophysical non‐invasive methods has been subsequently confirmed by direct inspection. 相似文献
6.
Jamal Asfahani 《水文研究》2007,21(8):1085-1097
A resistivity survey is conducted in Khanasser Valley, a semi‐arid region in northern Syria, to delineate the characteristics of ground water affected by the salt‐water intrusion related to Al‐Jaboul Sabkha. Existing wells were used to measure salinity and conductivity of water samplings. Vertical electrical sounding was carried out near the existing wells. The combination of resistivity and hydrogeological data enables the establishment of empirical relationships between earth resistivity, water resistivity, and the amount of total dissolved solids. These relationships are then used in order to derive salinity maps for electrode spacings of 70, 100, and 150 m. The distribution of fresh, brackish and salt‐water zones and their variations in space along two longitudinal profiles (LP1 and LP2) are established through converting subsurface depth–resistivity models into different ground‐water areas. The constructed ground‐water area maps allow interfaces between different water zones to be determined. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
7.
Improved surface-based geophysical technologies that are commercially available provide a new level of detail that can be used to guide ground water remediation. Surface-based multielectrode resistivity methods and tomographic seismic refraction techniques were used to image to a depth of approximately 30 m below the surface at the Natural and Accelerated Bioremediation Research Field Research Center. The U.S. Department of Energy (DOE) established the research center on the DOE Oak Ridge Reservation in Oak Ridge, Tennessee, to conduct in situ field-scale studies on bioremediation of metals and radionuclides. Bioremediation studies are being conducted on the saprolite, shale bedrock, and ground water at the site that have been contaminated with nitrate, uranium, technetium, tetrachloroethylene, and other contaminants (U.S. DOE 1997). Geophysical methods were effective in imaging the high-ionic strength plume and in defining the transition zone between saprolite and bedrock zones that appears to have a significant influence on contaminant transport. The geophysical data were used to help select the location and depth of investigation for field research plots. Drilling, borehole geophysics, and ground water sampling were used to verify the surface geophysical studies. 相似文献
8.
《水文科学杂志》2013,58(5):949-960
Abstract A geographical information system (GIS) was used for the integration of hydrological data acquired using remote sensing and geoelectrical techniques to understand the groundwater condition of Bakhar watershed, Mirazpur District, UP, India. Indian remote sensing IRS-1D, LISS—III data were used to prepare a geomorphological and lineament map of the Bakhar watershed. Vertical electrical sounding (VES) was carried out in different geomorphic units, and ranges of electrical resistivity values were assigned to the different formations by calibrating electrical resistivity with borehole data. Based on these, a subsurface resistivity map and an aquifer thickness map were prepared. Several layers were superimposed using GIS techniques. Each theme was assigned a weight, depending on its influence on groundwater recharge. Each class or unit in the map was assigned a knowledge-based rank from one to four, depending on its significance in storage and transmittance of groundwater, and these were then multiplied by the layer weighting to produce a score. Based on these scores, the watershed was categorized into different groundwater potential zones. The results indicate that the eastern and northern parts of the study area have very good groundwater potential to meet the demands of water for irrigation and domestic purposes, whereas the southern region has poor groundwater potential zones. Such integrated analysis has not been attempted so far in this region for hydrogeological investigation. 相似文献
9.
Kh.S. Gemail A.M. El-ShishtawyM. El-Alfy M.F. GhoneimM.H. Abd El-Bary 《Journal of Applied Geophysics》2011,75(1):140-150
1D resistivity sounding and 2D resistivity imaging surveys were integrated with geological and hydrochemical data to assess the aquifer vulnerability and saltwater intrusion in the north of Nile Delta, Egypt. In the present study, the El-Gharbyia main drain was considered as a case study to map the sand bodies within the upper silt and clay aquitard. Twenty Schlumberger soundings and six 2D dipole-dipole profiles were executed along one profile close to the western side of the main drain. In addition, 14 groundwater samples and 4 surface water samples from the main drain were chemically analyzed to obtain the major and trace elements concentrations.The results from the resistivity and hydrochemical data were used to assess the protection of the groundwater aquifer and the potential risk of groundwater pollution. The inverted resistivities and thicknesses of the layers above the aquifer layer were used to estimate the integrated electrical conductivity (IEC) that can be used for quantification of aquifer vulnerability. According to the aquifer vulnerability assessment of an underlying sand aquifer, the southern part of the area is characterized by high vulnerability zone with slightly fresh to brackish groundwater and resistivity values of 11-23 Ω.m below the clay cap. The resistivity sections exhibit some sand bodies within the clay cap that lead to increase the recharging of surface waste water (650 mg/l salinity) and flushing the upper part of underlying saltwater aquifer. The region in the north has saltwater with resistivity less than 6 Ω.m and local vulnerable zones within the clay cap. The inverted 2D dipole-dipole profiles in the vulnerable zones, in combination with drilling information have allowed the identification of subsoil structure around the main drain that is highly affected by waste water. 相似文献
10.
Zoltn Nagy 《Geophysical Prospecting》1996,44(6):1041-1083
Five examples, obtained during exploration for hydrocarbons in the Pannonian Basin of Hungary, are used to show how the interpretation of seismic sections can be usefully complemented by results from MT surveys. Selection of the most appropriate MT quantities, considered to be proper ‘MT attributes’ for the purpose of visualization as well as recognition of the subsurface structures and the different inversions of MT data is essential for practical integration of seismic and MT surveys. A new technique providing a semiquantitive MT-attribute pseudosection for the purpose of visualization of the subsurface structures is proposed. The procedure utilizes derivative functions of the phase of MT impedance for visualization and derives estimated depths from the Bostick transformation of Cagniard apparent resistivities. On the basis of the MT-attribute pseudosections, constructed from the phase derivatives and transformed resistivity data, depths are estimated for interfaces between geological formations with significant resistivity contrast. In particular examples, the interface between the Tertiary sediments and the older basement rocks as well as tectonic fracture zones with decreased resistivity can be resolved. 相似文献
11.
12.
Due to increase in population and agricultural activities, the aquifer of Quetta Valley is under tremendous stress and the water table is declining at an increasing rate. This situation necessitates evaluation of the aquifer system, for which information about geometry of the aquifer is a prerequisite. However, there are no drilling-to-bedrock data available; therefore, electrical resistivity, seismic reflection and gravity methods were employed to determine geometry of the aquifer. Interpretation of vertical electrical soundings provided information about the depth-tobedrock at some specific points, whereas seismic reflection delineated bedrock topography along two lines. The depths to bedrock inferred from electrical resistivity and seismic reflection data were used as constraints in the modeling of gravity data. 2.75D gravity models were constructed along lines with a regular spacing. Map of depth-to-bedrock was prepared by contouring the depth given by the gravity models. Combination of these geophysical methods depicted the geometry of the aquifer. This example shows that in a similar geological setting proper integration of geophysical exploration methods can determine the aquifer geometry with an acceptable reliability and at an appropriate cost. 相似文献
13.
Daan Herckenrath Nick Odlum Vanessa Nenna Rosemary Knight Esben Auken Peter Bauer‐Gottwein 《Ground water》2013,51(3):385-397
Salt water intrusion models are commonly used to support groundwater resource management in coastal aquifers. Concentration data used for model calibration are often sparse and limited in spatial extent. With airborne and ground‐based electromagnetic surveys, electrical resistivity models can be obtained to provide high‐resolution three‐dimensional models of subsurface resistivity variations that can be related to geology and salt concentrations on a regional scale. Several previous studies have calibrated salt water intrusion models with geophysical data, but are typically limited to the use of the inverted electrical resistivity models without considering the measured geophysical data directly. This induces a number of errors related to inconsistent scales between the geophysical and hydrologic models and the applied regularization constraints in the geophysical inversion. To overcome these errors, we perform a coupled hydrogeophysical inversion (CHI) in which we use a salt water intrusion model to interpret the geophysical data and guide the geophysical inversion. We refer to this methodology as a Coupled Hydrogeophysical Inversion‐State (CHI‐S), in which simulated salt concentrations are transformed to an electrical resistivity model, after which a geophysical forward response is calculated and compared with the measured geophysical data. This approach was applied for a field site in Santa Cruz County, California, where a time‐domain electromagnetic (TDEM) dataset was collected. For this location, a simple two‐dimensional cross‐sectional salt water intrusion model was developed, for which we estimated five uniform aquifer properties, incorporating the porosity that was also part of the employed petrophysical relationship. In addition, one geophysical parameter was estimated. The six parameters could be resolved well by fitting more than 300 apparent resistivities that were comprised by the TDEM dataset. Except for three sounding locations, all the TDEM data could be fitted close to a root‐mean‐square error of 1. Possible explanations for the poor fit of these soundings are the assumption of spatial uniformity, fixed boundary conditions and the neglecting of 3D effects in the groundwater model and the TDEM forward responses. 相似文献
14.
Geothermal electric power plant with a capacity of 10 mw has been now constructed by the Kyushu Electric Power Co. Ltd. at Otake, northern part of the Kyushu Island. Resistivity exploration, one of geophysical prospecting applied to this field in order to investigate the subsurface structure accompanied with natural steams, indicated low resistivity layer corresponding to altered zone of andesite due to hydrothermal agents. For the rapid interpretation of resistivity sounding curves, a method of calculating the standard curve for the multiple layered earth is developed in the utilization of an electronic digital computer. Some examples to show the application of this method are given, and tinally the result is described of resistivity measurement at Otake geothermal area. 相似文献
15.
Michel Chouteau Stefka Krivochieva Ramiro Rodriguez Castillo Tomas Gonzalez Moran Virginie Jouanne 《Journal of Applied Geophysics》1994,31(1-4)
A tensor magnetotelluric test survey was carried out in the region of Santa Catarina, located in the Chalco sub-basin of the Mexico Basin. The objective was to define the stratification at depth with an emphasis on the geometry of the main aquifer of that region which is partially known from DC resistivity soundings and drilling. High-quality magnetotelluric soundings could be recorded in the immediate vicinity of large urban zones because the sub-surface is very conductive. Interpretation shows that the solid bedrock is located at a depth of at least 800 m to the south and 1300 m to the north; it could, however, be much deeper. Using complementary DC resistivity sounding and well-logging data, three main layers have been defined overlying the bedrock. These layers are, from surface to bottom, an unsaturated zone of sand, volcanic ash and clay about 10 m thick, followed by a very conductive (1.5 ohm·m) 200 m thick layer of sand and ash with intercalated clay, saturated with highly mineralized water, and finally a zone with resistivity increasing gradually to 60 ohm·m. The investigated deep aquifer constitutes most of this third layer. It consists of a sequence of sand, gravel, pyroclastites and mainly fractured basalts. MT resistivity soundings and magnetic transfer functions also indicate that a shallow resistive structure is dipping, from the northwest, into the lacustrine deposits of the basin. This geologic feature is likely to be highly permeable fractured basaltic flows, which provide a channel by which water contaminated by the Santa Catarina landfill may leak into the basin. 相似文献
16.
Lahcen Zouhri 《水文研究》2010,24(10):1308-1317
An electrical prospecting survey is conducted in the Rharb basin, a semi‐arid region in the southern part of the Rifean Cordillera (Morocco) to delineate characteristics of the aquifer and the groundwater affected by the marine intrusion related to Atlantic Ocean. Analysis and interpretations of electrical soundings, bi‐logarithmic diagrams and the geoelectrical sections highlight a monolayer aquifer in the southern part, a multilayer system in the northern part of the Rharb basin and lenticular semi‐permeable formations. Several electrical layers have been deduced from the analysis of bi‐logarithmic diagrams: resistant superficial level (R0), conducting superficial level (C0), resistant level (R), intermediary resistant level (R′), conducting level (Cp) and intermediary layer of resistivity (AT). Spatial distribution of the resistivity deduced from the interpretation of apparent resistivity maps (AB = 400 and 1000 m) and the decreasing of resistivity values (35–10 Ωm), in particular in the coastal zone show that this heterogeneity is related to several anomalies identified in the coastal area, which result from hydraulic and geological processes: (i) heterogeneous hydraulic conductivity in particular in the southern part of the Rharb; (ii) lateral facies and synsedimentary faulting and (iii) the relationship between the electrical conductivity and chloride concentration of groundwater shows that salinity is the most important factor controlling resistivity. The distribution of fresh/salt‐water zones and their variations in space along geoelectrical sections are established through converting subsurface depth‐resistivity models. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
17.
Conceptual geological models based on geophysical data can elucidate aquifer architecture and heterogeneity at meter and smaller scales, which can lead to better predictions of preferential flow pathways. The macrodispersion experiment (MADE) site, with >2000 measurements of hydraulic conductivity obtained and three tracer tests conducted, serves as an ideal natural laboratory for examining relationships between subsurface flow characteristics and geophysical attributes in fluvial aquifers. The spatial variation of hydraulic conductivity measurements indicates a large degree of site heterogeneity. To evaluate the usefulness of geophysical methods for better delineating fluvial aquifer heterogeneities and distribution of preferential flow paths, a surface grid of two-dimensional ground penetrating radar (GPR) and direct current (DC) resistivity data were collected. A geological model was developed from these data that delineate four stratigraphic units with distinct electrical and radar properties including (from top to bottom) (1) a meandering fluvial system (MFS); (2) a braided fluvial system (BFS); (3) fine-grained sands; and (4) a clay-rich interval. A paleochannel, inferred by other authors to affect flow, was mapped in the MFS with both DC resistivity and GPR data. The channel is 2 to 4 m deep and, based on resistivity values, is predominantly filled with clay and silt. Comparing previously collected hydraulic conductivity measurements and tracer-plume migration patterns to the geological model indicates that flow primarily occurs in the BFS and that the channel mapped in the MFS has no influence on plume migration patterns. 相似文献
18.
Characterizing hydrological processes in a semiarid rangeland watershed: A hydrogeophysical approach
Austin M. Carey Ginger B. Paige Bradley J. Carr W. Steven Holbrook Scott N. Miller 《水文研究》2019,33(5):759-774
The complex ecohydrological processes of rangelands can be studied through the framework of ecological sites (ESs) or hillslope‐scale soil–vegetation complexes. High‐quality hydrologic field investigations are needed to quantitatively link ES characteristics to hydrologic function. Geophysical tools are useful in this context because they provide valuable information about the subsurface at appropriate spatial scales. We conducted 20 field experiments in which we deployed time‐lapse electrical resistivity tomography (ERT), variable intensity rainfall simulation, ground‐penetrating radar (GPR), and seismic refraction, on hillslope plots at five different ESs within the Upper Crow Creek Watershed in south‐east Wyoming. Surface runoff was measured using a precalibrated flume. Infiltration data from the rainfall simulations, coupled with site‐specific resistivity–water content relationships and ERT datasets, were used to spatially and temporally track the progression of the wetting front. First‐order constraints on subsurface structure were made at each ES using the geophysical methods. Sites ranged from infiltrating 100% of applied rainfall to infiltrating less than 60%. Analysis of covariance results indicated significant differences in the rate of wetting front progression, ranging from 0.346 m min?1/2 for sites with a subsurface dominated by saprolitic material to 0.156 m min?1/2 for sites with a well‐developed soil profile. There was broad agreement in subsurface structure between the geophysical methods with GPR typically providing the most detail. Joint interpretation of the geophysics showed that subsurface features such as soil layer thickness and the location of subsurface obstructions such as granite corestones and material boundaries had a large effect on the rate of infiltration and subsurface flow processes. These features identified through the geophysics varied significantly by ES. By linking surface hydrologic information from the rainfall simulations with subsurface information provided by the geophysics, we can characterize the ES‐specific hydrologic response. Both surface and subsurface flow processes differed among sites and are directly linked to measured characteristics. 相似文献
19.
P. P. G. Bruno V. Paoletti M. Grimaldi A. Rapolla 《Journal of Volcanology and Geothermal Research》2000,98(1-4)
Integrated geophysical surveys were performed in two sites, Fossa di Fuardo and Terme di San Calogero in Lipari Island, Southern Italy with the intent of the exploration of low-enthalpy geothermal fluids. Both sites show strong geochemical and geologic evidences of hydrothermal activity. The geophysical methods consist of two microgravimetric surveys, two 2D geoelectric profiles, a seismic reflection profile and a five seismic refraction profiles. The seismic methods allowed us to locate the main subsurface seismic discontinuities and to evaluate their geometrical relationships. The gravity field was used to constraint the seismic discontinuities, while the electric prospecting let discriminate more conductive areas, which could correspond to an increase in thermal fluid circulation in the investigated sites.The results obtained by the different geophysical methods are in good agreement and permit the definition of a reliable geo-structural model of the subsurface setting of the two investigated areas. A low-enthalpy geothermal reservoir constituted by a permeable pyroclastic and lava sequence underlying two shallow impermeable formations was found at Fossa del Fuardo. The reservoir is intersected by some sub-vertical faults/fractures that probably play an important role in convoying the thermal water up to the surface. At the other site, Terme di S. Calogero, the geophysical surveys showed that an intense circulation of fluids affects the subsurface of the area. This circulation concentrates along a ENE-trending fault located at a little distance from the thermal resort. The hot fluids may upraise along the fault if the width of the ascent area is smaller than 20 m. 相似文献
20.
In the last five years, magnetic resonance sounding (MRS), as a non-invasive geophysical method, has emerged as a new technique
for ground water investigation in Vietnam. In this paper, we present the general theoretical basis of this method together
with acquisition, processing, and interpretation of the MRS data. We show a case study of MRS surveys in sand dunes area in
order to characterize aquifers situated in the southern part of Vietnam. From the interpretation of MRS soundings we delimited
an aquifer layer in the subsurface with strong lateral variations for which we determined the depth at 44 m and water content
between 3% and 9.5%. The longitudinal relaxation constant T*1 is about 250 m s, while the transverse relaxation T*2 is between 150–200 m s. That indicates fine to medium grain size and thus low to medium hydraulic permeability. These results
are confirmed by the observations from the well LK1 between 45 to 70 m. The results of other MRS measurements showed the presence
of a low water bearing aquifer and were confirmed by the observations in two other wells. 相似文献