首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Electrical geophysical surveys in the mode of vertical electrical soundings (VES) and continuous vertical electrical soundings (CVES) were conducted in the León-Chinandega plains, northwestern Nicaragua, in order to obtain detailed information about the geometry of the different hydrogeological layers in the aquifer and depth to the basement. A total of 51 VES were carried out within the plains. The results show a complex structure towards the north east of the area, and the southwestern part of the plains presents a smoother stratification. The geoelectrical measurements and borehole information indicate that the basement topography is characterized by hills and deep valleys with highly variable basement depths. Fifty CVES where done in a smaller area in the center of the plain. The resistivity data yielded considerable information revealing the existence of two main geo-electrical units. The combined interpretation of geological and geophysical data shows an environment typical of sedimentary volcanic coastal plains. The information collected during this investigation provides valuable data for estimating the fresh-water resources of the León-Chinandega aquifer system and for development of a groundwater management plan.  相似文献   

2.
Groundwater preservation comprises a major problem in water policy. The comprehension of the groundwater/hydraulic systems can provide the means to approach this problem. Generally, drilling is expensive and time-consuming. On the other hand, new techniques have been applied during the last few decades that provide useful information on the depth and quality of aquifers. Among them, transient electromagnetic method (TEM) is an appealing method that provides fast results with minimum field crew and solves several hydrogeological problems. Many portable systems for single-site measurements are commercially available. The TEM-Fast 48HPC was used for acquiring 106 soundings in the northwestern Crete in Greece for defining the hydrogeological characteristics of the study area, since there were no available data from boreholes. Detailed geological, hydrolithological and tectonic survey was applied prior to the geophysical measurements. All the data were integrated to produce a secure and reliable hydrogeological model for the study area prior to any future hydrowell. Specifically, geometrical and hydraulic data of the study area groundwater were acquired. Two unconnected aquifers were detected and their possible contamination due to saltwater intrusion was analyzed and eliminated. Moreover, a location for borehole construction and groundwater pumping based on the potential of the aquifer system was proposed. Finally, the contribution of TEM (and electrical resistivity tomography) geophysical methods in studying complex coastal aquifers is shown by this work.  相似文献   

3.
复杂条件下地下水磁共振探测与灾害水源探查研究进展   总被引：4，自引：0，他引：4  
磁共振地下水探测是一种直接非侵害性探测地下水的地球物理新方法,与传统地球物理探测地下水方法相比,具有高分辨力、高效率、信息量丰富和解唯一等优点。近年来地下水磁共振探测技术发展迅速,不仅用于缺水地区的地下水勘查,还在地下灾害水源（由于地下水引起的灾害如堤坝渗漏、隧道/矿井水害、滑坡、海水入侵等）的探测预警中进行了探索性研究。综述了复杂条件下地下水磁共振探测技术的研究现状,包括强电磁干扰环境的自适应噪声压制、地下小水体的2D/3D磁共振探测、复杂条件的数据处理与反演、针对喀斯特地貌等地质环境的地下水磁共振与瞬变电磁联合探测研究成果,简要介绍了磁共振技术用于滑坡、海水入侵和隧道涌水等灾害水源探查的探索性研究示例,展望了地下水磁共振探测技术的未来发展趋势。  相似文献   

4.
Earth Fissures in Wadi Najran,Kingdom of Saudi Arabia   总被引：1，自引：0，他引：1  
The formation of earth fissures due to groundwater depletion has been reported in many places in North America, Europe, and Asia. Najran Basin is in the southern part of the Kingdom of Saudi Arabia, and agricultural activities and other groundwater uses have caused significant groundwater depletion there. The basin recently experienced a sudden appearance of numerous earth fissures. An interdisciplinary study consisting of an evaluation of land-use changes, and hydrological, hydrogeological, and geophysical investigations was conducted to determine the reason for the formation of the earth fissures. The hydrological analysis strongly revealed that the groundwater level is decreasing with time. Groundwater depletion would lead to the accumulation of subsurface stress, causing soil hydro-consolidation which creates the ideal condition for the formation of earth fissures. Electrical resistivity, data indicated that there are anomalies in the profiles, which are most probably due to the presence of subsurface topography, another key factor for the formation of the earth fissures.  相似文献   

5.
The groundwater hydrogeology of southern Tunisia emphasizes two main groundwater bodies so-called Zeuss-Koutine and south Gabes. These groundwater bodies yielding economically important storage of useful water present complex internal architecture and heterogeneity allowing exchange flows throughout permeable or/and fractured bodies. A geophysical survey using resistivity soundings was carried out along this area to describe in detail the field structure and the 3D extent of these groundwater bodies by the hydrogeological new data and detailed subsurface mapping based on resistivity sounding and seismic data. This survey discusses also the potentialities of some permeable layer in water storage and purposes potential favorable areas for optimum groundwater mining.  相似文献   

6.
An integrated study was carried out to investigate the subsurface geological conditions in a hard rock environment, with the aim of identifying zones with groundwater resource potential. The study, in Bairasagara watershed, Karnataka, India, considered geomorphology, water level, resistivity imaging, self potential, total magnetic field and susceptibility. The signatures due to lineaments have been clearly identified and their role in groundwater movement has been documented. Synthetic simulation methods were used to model the electrical response of the lineament using finite differential modeling scheme. The inverted image of the field data is compared with the synthetic image and iteration were performed on the initial model until a best match was obtained resulting on the generation of the calibrated resistivity image of the subsurface. Resistivity imaging revealed that the dykes are weathered/fractured to a depth of 6–8 m and are compact at deeper levels, and that they behave as barriers to groundwater movement, yet facilitate a good groundwater potential zone on the upgradient side. The results of magnetic surveys were utilized in differentiating granites and dolerite dykes with an insignificant resistivity contrast. Geomorphological expression alone cannot reveal the groundwater potential associated with a lineament. However, characterizing the nature of the feature at depth with integrated geophysical methods provides essential information for assessing that potential.An erratum to this article can be found at  相似文献   

7.
Groundwater models simulating flow in buried valleys interacting with regional aquifers are often based on hydrogeological models interpreted from dense geophysical datasets and scarce borehole data. For three simple synthetic cases, it is demonstrated that alternative methods of inversion of transient electro-magnetic (TEM) data can lead to very different interpretations of the hydrogeology inside and surrounding a buried valley. The alternative interpreted hydrogeological models are used in numerical modelling of groundwater flow to a pumping well. It is demonstrated that the alternative models result in quite different groundwater-model predictions of capture zone, recharge area, and groundwater age for the pumping well. It is briefly demonstrated that model calibration against hydraulic head data is not likely to improve the predictions or to identify the structural error of the interpreted hydrogeological models. It is therefore concluded that when TEM-based resistivity models are interpreted to construct the hydrogeological framework of a groundwater model, it must be done cautiously with support from deep borehole information. Too much reliance on geophysical mapping can lead to seriously wrong hydrogeological models and correspondingly wrong groundwater-model predictions.  相似文献   

8.
An integrated study was carried out to investigate the subsurface geological conditions in a hard rock environment, with the aim of identifying zones with groundwater resource potential. The study, in Bairasagara watershed, Karnataka, India, considered geomorphology, water level, resistivity imaging, self potential, total magnetic field and susceptibility. The signatures due to lineaments have been clearly identified and their role in groundwater movement has been documented. Synthetic simulation methods were used to model the electrical response of the lineament using finite differential modeling scheme. The inverted image of the field data is compared with the synthetic image and iteration were performed on the initial model until a best match was obtained resulting on the generation of the calibrated resistivity image of the subsurface. Resistivity imaging revealed that the dykes are weathered/fractured to a depth of 6–8 m and are compact at deeper levels, and that they behave as barriers to groundwater movement, yet facilitate a good groundwater potential zone on the upgradient side. The results of magnetic surveys were utilized in differentiating granites and dolerite dykes with an insignificant resistivity contrast. Geomorphological expression alone cannot reveal the groundwater potential associated with a lineament. However, characterizing the nature of the feature at depth with integrated geophysical methods provides essential information for assessing that potential.The online version of the original article can be found at  相似文献   

9.
Electrical resistivity method is a versatile and economical technique for groundwater prospecting in different geological settings due to wide spectrum of resistivity compared to other geophysical parameters. Exploration and exploitation of groundwater, a vital and precious resource, is a challenging task in hard rock, which exhibits inherent heterogeneity. In the present study, two-dimensional Electrical Resistivity Tomography (2D-ERT) technique using two different arrays, viz., pole–dipole and pole–pole, were deployed to look into high signal strength data in a tectonically disturbed hard rock ridge region for groundwater. Four selected sites were investigated. 2D subsurface resistivity tomography data were collected using Syscal Pro Switch-10 channel system and covered a 2 km long profile in a tough terrain. The hydrogeological interpretation based on resistivity models reveal the water horizons trap within the clayey sand and weathered/fractured quartzite formations. Aquifer resistivity lies between ～3–35 and 100–200 Ωm. The results of the resistivity models decipher potential aquifer lying between 40 and 88 m depth, nevertheless, it corroborates with the static water level measurements in the area of study. The advantage of using pole–pole in conjunction with the pole–dipole array is well appreciated and proved worth which gives clear insight of the aquifer extent, variability and their dimension from shallow to deeper strata from the hydrogeological perspective in the present geological context.  相似文献   

10.
The subsurface data are a basic requirement for the set up of hydrogeological framework. Geographic information systems (GIS) tools have proved their usefulness in hydrogeology over the years which allow for management, synthesis, and analysis of a great variety of subsurface data. However, standard multi-layered systems are quite limited for modeling, visualizing, and editing subsurface data and geologic objects and their attributes. This paper presents a methodology to support the implementation of hydrogeological framework of the multi-layered aquifer system in Nabeul–Hammamet (NH) coastal region (NE, Tunisia). The methodology consists of (1) the development of a complete and generally accepted hydrogeological classification system for NH aquifer system (2) the development of relational databases and subsequent GIS-based on geological, geophysical and hydrogeological data, and (3) the development of meaningful three-dimensional geological and aquifer models, using GIS subsurface software, RockWorks 2002. The generated 3-D geological models define the lithostratigraphy and the geometry of each depositional formation of the region and delineate major aquifers and aquitards. Where results of the lithologic model revealed that there is a wide range of hydraulic conductivities in the modeled area, which vary spatially and control the groundwater flow regime. As well, 17 texturally distinct stratigraphic units were identified and visualized in the stratigraphic model, while the developed aquifer model indicates that the NH aquifer system is composed of multi-reservoir aquifers subdivided in aquifers units and separated by sandy clay aquitards. Finally, this study provides information on the storing, management and modeling of subsurface spatial database. GIS has become a useful tool for hydrogeological conceptualization and groundwater management purposes and will provide necessary input databases within different groundwater numerical models.  相似文献   

11.
A group of 36 coral islands is being scattered in the Arabian Sea off the western coast of India. On such islands, groundwater is the only source of fresh water for the islanders. The demand for groundwater is increasing every year due to growing population and urbanization. On the other side the peculiar hydrologic, geologic and geomorphic features restrict the availability of groundwater. Thus a proper understanding of the groundwater condition is important in order to meet this increasing demand and also to formulate future development and management strategies. Detailed hydrogeological, geophysical and hydrochemical studies had been carried out to identify potential fresh groundwater resources and quantify vulnerable parts of Andrott Island, Union Territory of Lakshadweep. Systematic collection and analysis of hydrological, geophysical and hydrochemical data gives an early signal of deterioration in groundwater quality in the peripheral parts of eastern and western coasts of this island and it suggests immediate measures for arresting the deterioration in groundwater quality as well as augmentation for restoration of aquifer in some parts of the island.  相似文献   

12.
Saltwater intrusion is generally related to seawater-level rise or induced intrusion due to excessive groundwater extraction in coastal aquifers. However, the hydrogeological heterogeneity of the subsurface plays an important role in (non-)intrusion as well. Local hydrogeological conditions for recharge and saltwater intrusion are studied in a coastal groundwater system in Vietnam where geological formations exhibit highly heterogeneous lithologies. A three-dimensional (3D) hydrostratigraphical solid model of the study area is constructed by way of a recursive classification procedure. The procedure includes a cluster analysis which uses as parameters geological formation, lithological composition, distribution depth and thickness of each lithologically distinctive drilling interval of 47 boreholes, to distinguish and map well-log intervals of similar lithological properties in different geological formations. A 3D hydrostratigraphical fence diagram is then generated from the constructed solid model and is used as a tool to evaluate recharge paths and saltwater intrusion to the groundwater system. Groundwater level and chemistry, and geophysical direct current (DC) resistivity measurements, are used to support the hydrostratigraphical model. Results of this research contribute to the explanation of why the aquifer system of the study area is almost uninfluenced by saltwater intrusion, which is otherwise relatively common in coastal aquifers of Vietnam.  相似文献   

13.
Remote sensing data can be integrated with analyses of topography, structural geology, hydrogeology and geophysics. The integration gives premises for the delineation of zones of potential groundwater resources in strongly fractured and karstified deep aquifers in the uplifted Meo Vac Highland, northern Vietnam. Remote sensing analysis outlines geological faults with hydrogeological significance. These faults are combined with a derived lineament density map, interpreted analysis of surface flow direction and existing hydrogeological data, resulting in indications of groundwater flow direction. An analysis of the SPOT 5 band ratio 4/1, together with indications of surface-flow direction in low terrains, results in a determination of underground cavern passages. The delineated zones of potential groundwater resources are verified by detailed hydrogeological field surveys and geophysical measurements. Remote sensing analysis is shown to effectively contribute to the investigation of groundwater resources for a hydrogeologically complex area.  相似文献   

14.
Groundwater in a coral island   总被引：4，自引：3，他引：1  
 Freshwater aquifers in small coral islands usually occur as thin lenses which are significantly influenced by stresses such as groundwater pumping, sea tides, etc. Kavaratti, a coral island, is one of the 36 such islands in the Arabian Sea off the western coast of India. Detailed hydrogeological investigations were carried out to determine the quantity of freshwater that could be pumped in addition to the present usage. Salinity of groundwater must remain within permissible limits and a 2-D solute mass transport model with a vertical section of the island was constructed by the computer code SUTRA. The model was calibrated by obtaining a match of computed and observed values of the water table, tidal efficiency, and salinity of groundwater at the water table. The model analysis showed that the salinity of groundwater continues to increase unless groundwater pumping is kept below a certain rate. Groundwater potential can be augmented by reducing the subsurface outflow to the sea and by raising the water table by a subsurface dam. Received: 8 September 1997 · Accepted: 27 April 1998  相似文献   

15.
The impact of mining causes deterioration of environment and decline of groundwater level in the adjoining mining areas, which influences groundwater source for domestic and agriculture purposes. This necessitated locating and exploiting of new groundwater source. A fast, cost-effective and economical way of locating and exploration is to study and analyze remote sensing data. Interpreted remote sensing data were used to select sites for carrying out surface geophysical investigations. Various geomorphologic units were demarcated, and the lineaments were identified by interpretation of false color composite satellite imageries. The potential for occurrence of groundwater in the Sukinda Valley was classified as very good, good, moderate and poor by interpreting the images. Sub-surface geophysical investigations, namely vertical electrical soundings, were carried out to delineate and demarcate potential water-bearing zones. Integrated studies of interpretation of geomorphologic, lineaments and geophysical data (aquifer thickness) were used to prepare groundwater potential map. The studies reveal that the groundwater potential of shallow aquifers is due to geomorphologic features, and the potential of deeper aquifers is determined by lineaments and degree of weathering.  相似文献   

16.
瞬变电磁法在甘肃寻找地下含水构造中的应用   总被引：2，自引：2，他引：2  
在甘肃省部分地区的地下水勘查工作中,用常规物探方法难以划分地层的结构、确定断裂构造的位置、查明基岩面的起伏形态及判断地下水的赋存状况。通过TEM勘测并结合钻孔资料分析,对上述水文地质问题有了一些突破性的认识,证明了瞬变电磁法在地下水勘查工作中的有效性。  相似文献   

17.
The increasing demand for freshwater has necessitated the exploration for new sources of groundwater, particularly in hard rock terrain, where groundwater is a vital source of freshwater. A fast, cost effective, and economical way of exploration is to study and analyze geophysical resistivity survey data. The present study area Omalur taluk, Salem District, Tamil Nadu, India, is overlain by Archaean crystalline metamorphic complex. The study area is a characteristic region of unconfined aquifer system. The potential for occurrence of groundwater in the study areas was classified as very good, good, moderate, and poor by interpreting the subsurface geophysical investigations, namely vertical electrical soundings, were carried out to delineate potential water-bearing zones. The studies reveal that the groundwater potential of shallow aquifers is due to weathered zone very low resistivity and very high thickness and the potential of deeper aquifers is determined by fracture zone very low resistivity and very high thickness area. By using conventional GIS method, the spatial distribution maps for different layer (top soil, weathered zone, first fracture zone, and second fracture zone) thicknesses were prepared. The geoelectrical approach was successfully applied in the study area and can be therefore easily adopted for similar environments.  相似文献   

18.
水文地质调查与综合物探在赣南花岗岩地区找水中的应用   总被引：1，自引：0，他引：1  
刘声凯 《地质与勘探》2021,57(3):584-592
为解决赣南革命老区缺水村落的饮水安全问题,在中国地调局赣南饮水安全项目的支撑下,对赣南20个扶贫点开展了找水工作。本文以宁都县花岗岩地区的4个找水点为例,介绍水文地质调查与综合物探结合的找水方法与技术。首先通过调查各测区水文地质条件,明确找水方向并布置物探测线,然后合理选择综合物探方法和工作参数,确定数据处理与资料解释方法,最后通过物探成果分析与钻探验证,归纳总结了水文地质调查与综合物探方法相结合在花岗岩地区找水中的经验与教训,能够为花岗岩地区开展地下水勘查工作提供有益的参考和借鉴。  相似文献   

19.
Information on the distribution of subsurface temperature and hydraulic heads at 24 observation wells in and around the Tokyo Lowland, the eastern part of the Tokyo Metropolitan area, were examined to make clear the relationship between groundwater and the subsurface thermal environment in the urban area. Minimums in temperature–depth logs due to subsurface temperature increasing at shallow parts were recognized in 21 wells. This fact shows subsurface temperature is affected by ground surface warming in almost all of this area. Deeper than minimums, where the effects of surface warming became relatively small, regional variation is observed as follows: high temperatures are shown in the central part to the southern part, and low temperatures shown in the inland to eastern part. The high temperature area corresponds to an area where the lower boundary of groundwater flow is relatively shallow. This area corresponds also to an area with severe land subsidence resulting from excessive groundwater pumping. It is considered that this high temperature area is formed by the effects of upward groundwater flow affected by hydrogeological conditions and pumping. On the other hand, a comparison between past data (1956–1967) and present data (2001–2003) revealed widespread decreasing temperature in the inland area. This is explained by downward groundwater flow based on an analysis of temperature–depth logs. This fact suggests that subsurface temperature is not only increasing from the effects of surface warming but also decreasing from the effects of groundwater environment change due to pumping.  相似文献   

20.
Geoelectrical resistivity investigation using Vertical Electrical Sounding (VES) technique was conducted at Port Blair, South Andaman Island, to locate the fractures in different formations and to decipher its groundwater potential. A total of 40 VES were carried out covering the entire study area using Schlumberger electrode configuration out of which 34 VES fall in Andaman Flysch formations and the remaining VES in Ophiolite formations. The interpreted resistivity results were integrated with nine borehole lithologs for the subsurface analysis. The combination of VES with borehole litholog data has provided a close correspondence on subsurface hydrogeological conditions. The interpreted VES data of various formations showed drastic variations in the resistivity ranging from higher in Ophiolite, moderate in Andaman Flysch and very low in valleys of Andaman Flysch formations. The study further revealed that the weathered and fractured volcanics of Ophiolite groups of rocks and sandstone that occur in the Andaman Flysch formations constitute the productive water bearing zones categorized as good groundwater potential zone. Based on the geoelectrical parameters, viz., thickness of layers and the layer resistivity values, a groundwater potential map was prepared, in which good, moderate, and poor groundwater zones were demarcated. Further, numerical, spatial and litho-geoelectric models of resistivity were analyzed in terms of groundwater potential and these models have thus enabled to prepare a comprehensive groundwater development and management plans proving its efficacy in this art of exploratory investigations.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号