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Quantitative Integration of High-Resolution Hydrogeophysical Data: A Novel Approach to Monte-Carlo-Type Conditional Stochastic Simulations and Implications for Hydrological Predictions

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Journal of China University of Geosciences 2009年第3期20卷 580-591页

作者： Baptiste Dafflon James Irving Klaus Holliger Institute of Geophysics University of LausanneCH-1015 Lausanne Switzerland

Geophysical techniques can help to bridge the inherent gap that exists with regard to spatial resolution and coverage for classical hydrological methods. This has led to the emergence of a new and rapidly growing research domain generally referred to as hydrogeophysics. Given the differing sensitivities of various geophysical techniques to hydrologically relevant parameters, their inherent trade-off between resolution and range, as well as the notoriously site-specific nature of petrophysical parameter relations, the fundamental usefulness of multi-method surveys for reducing uncertainties in data analysis and interpretation is widely accepted. A major challenge arising from such endeavors is the quantitative integration of the resulting vast and diverse database into a unified model of the probed subsurface region that is consistent with all available measurements. To this end, we present a novel approach toward hydrogeophysical data integration based on a Monte-Carlo-type conditional stochastic simulation method that we consider to be particularly suitable for high-resolution local-scale studies. Monte Carlo techniques are flexible and versatile, allowing for accounting for a wide variety of data and constraints of differing resolution and hardness, and thus have the potential of providing, in a geostatistical sense, realistic models of the pertinent target parameter distributions. Compared to more conventional approaches, such as co-kriging or cluster analysis, our approach provides significant ad- vancements in the way that larger-scale structural information eontained in the hydrogeophysieal data can be accounted for. After outlining the methodological background of our algorithm, we present the results of its application to the integration of porosity log and tomographic crosshole georadar data to generate stochastic realizations of the detailed local-scale porosity structure. Our procedure is first tested on pertinent synthetic data and then applied to a fiel

关键词： aquifer characterization conditional simulation geostatistics hydrogeophysics hydrology quantitative data integration Monte Carlo methods simulated annealing flow and transport modeling.

Landslide monitoring in southwestern China via time-lapse electrical resistivity tomography

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Applied Geophysics 2016年第1期13卷 1-12,217页

作者：徐冬胡祥云单春玲李睿恒中国地质大学(武汉)地球物理与空间信息学院地球内部多尺度成像湖北省重点实验室武汉430074

The dynamic monitoring of landslides in engineering geology has focused on the correlation among landslide stability,rainwater infiltration,and subsurface ***,the understanding of this complicated correlation is still poor and ***,in this study,we investigated a typical landslide in southwestern China via time-lapse electrical resistivity tomography（TLERT） in November 2013 and August *** studied landslide mechanisms based on the spatiotemporal characteristics of surface water infiltration and flow within the landslide *** with borehole data,inverted resistivity models accurately defined the interface between Quaternary sediments and *** flow pathways attributed to fracture zones and fissures were also *** addition,we found that surface water permeates through these pathways into the slipping mass and drains away as fissure water in the fractured bedrock,probably causing the weakly weathered layer to gradually soften and erode,eventually leading to a ***,TLERT dynamic monitoring can provide precursory information of critical sliding and can be used in landslide stability analysis and prediction.

关键词： time-lapse electrical resistivity tomography landslide hydrogeophysics monitoring preferential flow

2D TEM Modeling for a Hydrogeological Study in the ParanáSedimentary Basin, Brazil

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International Journal of Geosciences 2017年第5期8卷 693-710页

作者： Emerson Rodrigo Almeida Jorge Luís Porsani Fernando Acácio Monteiro dos Santos Cassiano Antonio Bortolozo Universidade de Sã o Paulo Instituto de Astronomia Geofísica e Ciências Atmosféricas Departamento de Geofísica. Rua do Mat&atilde o Butant&atilde S&atilde o Paulo Brazil Universidade de Lisboa-IDL Lisboa Portugal

This work uses 2D TEM (Transient Electromagnetic) modeling for a hydrogeological study in the Paraná sedimentary basin. The study area is located at the northern region of the state of S?o Paulo, Brazil, where groundwater is exploited from two aquifer systems: one sedimentary, shallow, and the other crystalline, deep. The interest in applying the TEM method in this area owes to the high exploitation rates of groundwater from the crystalline aquifer system for irrigation, which is triggering considerable seismic activity locally. This aquifer system is composed of fractured basalt within the Serra Geral Formation and is about 120 m deep. Eighty-six TEM soundings were acquired at this location, but in nine cases the data did not fit the modelled curve for 1D geoelectrical models due to the geological complexity of the area. This paper shows 2D geoelectrical modeling results based on the FDTD (Finite Differences in Time Domain) method to explain the lateral resistivity variation within the geological setting. A 2D model was generated for each sounding and compared with 1D inversion models as well as with direct information from wells. The results show some vertical variations of about 10 to 30 meters on the upper interface of the basalt layer from Serra Geral Formation. They are located at approximately 60 meters from the center of the soundings. The existence of these 2D structures in the subsurface can be related to the drainage system in the study area. The presence of these structures may indicate a connection between the shallow and deep aquifer systems, acting like a conduit that may contribute to the seismic activity reported.

关键词： Transient Electromagnetic (TEM) 2D Modeling hydrogeophysics Paraná Basin Brazil

Electrical Resistivity Tomography and TDEM Applied to Hydrogeological Study in TaubatéBasin, Brazil

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International Journal of Geosciences 2018年第2期9卷 119-130页

作者： Rodrigo Corrêa Rangel Jorge Luís Porsani Cassiano Antonio Bortolozo Luiz Rodrigo Hamada Universidade de Sã o Paulo Instituto de Astronomia Geofísica e Ciências Atmosféricas Departamento de Geofísica S&atilde o Paulo Brazil CEMADEN—National Center for Natural Disaster Monitoring and Alert General Coordination of Research and Development S&atilde o José dos Campos Brazil

This research applies Electrical Resistivity Tomography (ERT) and Time Domain Electromagnetic Method (TDEM) to study the hydrogeology of the Taubaté basin, which is characterized by half-grabens with about 850 m of maximum sediments thickness. The study area is in Taubaté city, São Paulo State, Brazil, where the Taubaté aquifer is an important water source. The Taubaté Group is the main sedimentary package of the basin;it is formed mainly by shales that form aquicludes, and thin layers of sandstones that form the aquifer. There are 40 groundwater exploration wells in Taubaté city that provide important information. The study purpose is to characterize the geoelectrical stratigraphy of the subsurface to locate the contact between the Quaternary and Tertiary sediments and to identify the Taubaté aquifer. The ERT is used for shallow investigations (tens of meters) and the TDEM can reach a great investigation depth (hundreds of meters). Therefore, these geophysical methods are complementary. The ERT data were acquired with the pole-dipole array with 20 m of electrodes spacing and 400 m length, and the TDEM data with the central-loop array with a 200 × 200 m transmitter loop. The results permit to define the contact between the Quaternary and Tertiary sediments around 15 m depth, the Pindamonhangaba Formation between 15 m and 30 m depth and the Taubate Group between 30 m and 300 m depth. The TDEM method defined the Taubaté Group as a single geoelectric layer because the shale and the sandstone layers are all very conductive. The basement is formed by gneiss, which is a very resistive rock. The TDEM method is not able to identify a high conductor/resistor contrast. Overall, the results are consistent with the known geology and the wells information.

关键词： Electrical Resistivity Tomography (ERT) Time Domain Electromagnetic (TDEM) hydrogeophysics Taubaté Basin Brazil

Geophysical and Hydrological Investigations of the Northern Wadis Area of Azraq Basin for Groundwater Artificial Recharge Purposes

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International Journal of Geosciences 2016年第5期7卷 744-760页

作者： Hani Al-Amoush Abdel Rahman Al-Shabeeb Saad Al-Ayyash Rida Al-Adamat Majed Ibrahim A’kif Al-Fugara Jaafar Abu Rajab Institute of Earth and Environmental Sciences Al al-Bayt University Mafraq Jordan Faculty of Engineering Al al-Bayt University Mafraq Jordan Natural Resources Faculty Hashemite University Zarqa Jordan

Geophysical study and watershed hydrological delineation have been integrated at downstream of Alasra dam site Norh Azraq area to investigate their potential for artificial groundwater recharge. The total surface area of the watershed was found to be about 195 square kilometers. The estimated annual runoff volumes for the Alasra watershed ranged between 1.2 and 1.8 MCM. Moreover, the interpretation of Ten Time Domain Electromagnetic (TDEM) soundings suggested three principal subsurface layers. The top surface layer has an intermediate resistivity (90 - 110 Ohm·m) with a thickness ranging from a few meters to around 50 m. This layer was interpreted as superficial deposits. The second subsurface layer with variably high resistivity values is composed of unsaturated massive basalt layer and probably belongs to Madhala Olivine Phyric Basalt Formation (MOB). The large variations in resistivity could be ascribed to the degree of water saturation (as a result of groundwater recharge from the nearby harvested water dam), or lithological variations (clay content) and/or due to structural control. The third subsurface layer has low resistivity values (·m to 40 Ω·m) and was found at a depth ranging from 120 to 150 m. This layer could represent a saturated basalt layer with high clay contents. The subsurface structures and major faults have been identified. Based on the results of this study, a combination of surface and subsurface artificial groundwater recharge techniques is highly recommended.

关键词： TDEM Groundwater Recharge Alasra hydrogeophysics Azraq Jordan

Relevance of AEM and TEM to Detect the Groundwater Aquifer at Faiyum Oasis Area, Faiyum, Egypt

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International Journal of Geosciences 2014年第6期5卷 611-621页

作者： A. A. Basheer A. I. Taha A. El-Kotb F. A. Abdalla S. O. Elkhateeb Geology Department Faculty of Science South Valley University Qena Egypt Geomagnetic and Geoelectric Department National Research Institute of Astronomy and Geophysics Cairo Egypt

This study investigates the groundwater aquifer located in Fayuim oasis. In this study, two of the electromagnetic measurement methods have been used in determining the hydrological situation in the Fayoum oasis. The first is airborne electromagnetic (AEM) which, sometimes is referred to as Helicopter electromagnetic (HEM) and the second is ground Time-domain Electromagnetic method (TEM). The subsurface consists of four geoelectrical layers with a rough slope towards the center. The third and the fourth layers in the succession are suggested to be the two-groundwater aquifers. The third layer saturates with fresh water overlying saline water which exists in the bottom of the second one. It is worth mentioning that the depth of the fresh water surface undulates between the surface level in two lakes in the study area and 57 meters below the ground, whereas the thickness of the fresh water aquifer varies from 13 to 36 meters. The depth of the saline water surface undulates between 59 and 81 meters below the ground. In general, airborne electromagnetic surveying has the advantage of fast resistivity mapping with high lateral resolution. Groundbased geophysical surveys are often more accurate, but they are definitely slower than airborne surveys. It depends on targets of interest, time, budget, and manpower available by the method or the combination of methods that will be chosen. A combination of different methods is useful to obtain a detailed understanding of the subsurface resistivity distribution.

关键词： Airborne Electromagnetic [Frequency-Domain] Ground Electromagnetic [Time-Domain] AEM TEM hydrogeophysics Al Faiyum Oasis/Lake Egypt

Mapping deeply-buried geothermal faults using microtremor array analysis

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Mapping deeply-buried geothermal faults using microtremor ar...