Groundwater Exploration in Tirtoadi using the Geoelectric Schlumberger Method

Tirtoadi sub-district is one of the areas mentioned as being on alert for meteorological drought, which is a condition of not experiencing a day without rain (HTH) for more than 60 days. This research aims to provide information on the presence of subsurface water using geoelectric methods. Data acquisition was carried out at 20 points in Tirtoadi. The distribution of points is random but evenly distributed in the research area. The equipment used is Syscal Jr and the measuring range is 600 m AB, and the direction of the stretch is relatively north to south. The field data obtained are deltas V and I. These data are used to calculate R and Rho. The resistivity value obtained is the apparent resistivity. To obtain a subsurface model of the actual resistivity, it is necessary to perform a 1-D inversion. The inversion is carried out using the Progress V3.0 software. The results obtained in this study are variations in the value of subsurface resistivity. Resistivity of water-containing aquifers ranges between 10 ?m – 50 ?m. The depth of groundwater varies between 50 meters to 80 meters. The thickness of the groundwater varies between 5 meters to 22 meters. The recommended drill point is given at T11 with coordinates 49 S 424996 N 9144372 E because at this point it has the shallowest depth and thick enough thickness.

Integrasi Metode Resistivitas, Seismik Refraksi, Geologi Berbasis Geospasial untuk Identifikasi Potensi Longsor di Srimartani, Yogyakarta

Kabupaten Bantul merupakan salah satu kabupaten yang berpotensi terjadi tanah longsor, tepatnya di daerah Srimartani, Kecamatan Piyungan. Penelitian ini dilakukan dengan tujuan untuk mendapatkan data dan informasi mengenai parameter metode geofisika daerah longsor dan mengetahui dugaan zona potensi longsor. Metode yang digunakan dalam penelitian ini adalah survei lokasi, akuisisi metode seismik refraksi, akuisisi metode resistivitas, dan pemetaan foto udara (geospasial). Dari penampang bawah permukaan seismik refraksi metode hagiwara didapatkan bahwa lapisan lapuk pada daerah riset berupa soil dan pasir tuffan dikarenakan memiliki sifat permeable dan bidang gelincirnya yang bersifat impermeable. Pada penampang bawah metode seismik refraksi lapisan pertama yaitu soil dengan kecepatan V1 sekitar 313.8 m/s – 461.6 m/s dan lapisan kedua yaitu pasir dengan kecepatan V2 sekitar 459 m/s – 1567 m/s. Sementara penampang bawah permukaan metode resistivitas konfigurasi dipole – dipole didapatkan lapisan lapuk tersebut memiliki nilai resitivitas yang kecil dikarenakan lapisan tersebut bersifat lunak sehingga ada kemungkinan lapisan tersebut dalam kondisi basah. Pada penampang resistivitas memiliki nilai 126 ohm.m hingga lebih dari 301 ohm.m, daerah tersebut diperkirakan terdapat batuan breksi batuapung dari formasi semilir yang diduga sebagai bidang gelincir. Dari segi geologi, daerah penelitian sangat rentan terjadi tanah longsor dikarenakan kondisi lereng searah dengan kondisi struktur regional di daerah penelitian yaitu barat-timur, didukung oleh kondisi batuan yang ada berupa breksi batuapung dan tuff yang sangat rawan terjadi longsor. Dengan adanya penelitian ini, diharapkan dapat menambah pengetahuan mengenai antisipasi masyarakat dalam meminimalisir dampak yang ditimbulkan dari adanya tanah longsor. Bantul Regency is one of the districts that have the potential for landslides to occur, precisely in the Srimartani area, Piyungan District. This research was conducted with the aim of obtaining data and information about the parameters of the geophysical method of landslide areas and knowing the alleged landslide potential zone. The methods used in this research are site survey, seismic refraction acquisition method, resistivity method acquisition, and aerial photography (geospatial) mapping. From the subsurface seismic refraction of the Hagiwara method, it was found that the weathered layer in the research area was soil and sand due to its permeable properties and impermeable slip plane. . In the lower section of the seismic refraction method, the first layer is soil with a V1 velocity of around 313.8 m/s – 461.6 m/s and the second layer is sand with a V2 velocity of about 459 m/s – 1567 m/s. While the subsurface resistivity method of the dipole - dipole configuration found that the weathered layer has a small resistivity value because the layer is soft so there is a possibility that the layer is in a wet conditionIn the cross section resistivity has a value of 126 ohm.m to more than 301 ohm.m, the area is estimated to contain pumice breccia from the breccia formation which is thought to be a slip plane. In terms of geology, the research area is very susceptible to landslides because the slope conditions are in line with the regional structural conditions in the research area, namely west-east, supported by the existing rock conditions in the form of pumice breccia and tuff which are very prone to landslides. With this research, it is hoped that it can increase knowledge about community anticipation in minimizing the impact of landslides.

Identifikasi lapisan akuifer menggunakan metode geolistrik konfigurasi wenner di daerah kering desa Kalitengah kecamatan Panggungrejo kabupaten Blitar

Kalitengah Village, Kecamatan Panggungrejo, Kabupaten Blitar is a lack of ground water place, most of it is karst area. In dry season, villagers had to do hard work to find clean water source. They even have to buy it from another place. it was happened because not all of their well produces adequate amount of clean water. This research purposed to get information about spread and depth of the aquifer layer in Kalitengah Village, KecamatanPanggungrejo, Kabupaten Blitar in order to make new source of clean water. By using value of rock resistivity and subsurface structure information, clean water source can be located. The method of this research is geo-electrical wenner configuration with sounding technique. One point of sounding applied at known well as reference, and 25 points of sounding with 5 m separation as guess mapping the presence of subsurface aquifer. Acquisition have done by locate the current and potential electrodes position. Then, the current was injected until value of apparent resistivity appeared. These processes repeated until the entire area has been mapped.The result showed the subsurface resistivity value of research area. The resistivity of ground water in reference sounding point is 28-32 Ohm-meters and found in 15m below the surface. in sounding point 1-20, there is no presence of ground water aquifer. Interpretation on the result of software ZondRes2D shows resistivity value less than 28-32 Ohm-meters. The resistivity of ground water in reference sounding point is 28-32 Ohm-meters and found in 15m below the surface. Aquifer layer found at point 1 - 25 with dept about 7, 25 - 18,5 m, interpretation on the result of software ZondRes2D. The aquifer became thicker from sounding point 1 to 25 and from 3D section showed the spread of aquifer is tend to south and west.

Andesite prospect at West Sungkai of North Lampung: Its distribution based on electrical resistivity tomography

Infrastructure construction made andesite’s demand has increased, particularly in Lampung Province. In this research, its distribution in West Sungkai of North Lampung is mapped based on Electrical Resistivity Tomography (ERT) data from 6 lines, each of them was 186 m in length. Due to its excellent vertical resolution, Wenner configuration is performed. The research area is part of Quarter Holocene Volcanic (Qhv) formation. Lajur Barisan members consist of volcanic breccia, lava, and andesite-basalt tuff; thus, resistivity modeling is built within this aisle. Subsurface resistivity model has been created using the non-linear inversion method with promising low error at the third to fifth iterations, which marks an acceptable value. Using 2D and 3D ERT modeling, it is estimated that there are three mains of rocks based on their resistivity value: sandy tuff with 65 – 212 Ω m; tuff with 212 – 655 Ω m; and andesite with resistivity more than 655 Ω m. Andesite within this area is likely lava andesite which spread from the middle to the West and north. It is located at 5 – 35 m in depths with the reserve estimation of andesite is about 1.65 million tons.

Application of a Wide-Field Electromagnetic Method for Hot Dry Rock Exploration: A Case Study in the Gonghe Basin, Qinghai, China

Hot dry rock (HDR) is a geothermal resource with a high temperature that is widely distributed and has good potential as a clean and renewable energy source. To determine underground electrical structures and to predict granite reservoir distributions, the wide-field electromagnetic (WFEM) method has been applied to explore deep mineral resources and has advantages such as explorations at greater depths and at high resolutions. In this study, a WFEM investigation was carried out for HDR exploration in Gonghe Basin within Qinghai Province. Six parallel survey lines, each spaced apart by 1 km, were designed for WFEM data acquisition. After data processing and inversion, we mapped the subsurface resistivity distribution and divided the inversion resistivity of HDR in the Qiabuqia area into four layers. From the WFEM results, we inferred the location of HDRs, which was verified using drilling wells. HDRs were found at a depth between 3200 m and 3705 m in the well. Furthermore, with the calibration of drilling well GR1, we provided the relationship between temperature and inversion resistivity. From this relationship, the exploration areas with mining potential can be determined.

Identification of Reclamation Area in Ancol of North Jakarta Using Resistivity Method

The coastal reclamation area is an expansion of coastal areas through technical engineering to develop new land areas. Identification of the reclamation area can be performed by detecting subsurface imaging using the resistivity method. This study used a multi-electrode (multichannel) resistivity imaging method. The resistivity imaging results show a good response of subsurface resistivity and successfully identified reclamation area with low resistivity <27.8 Ωm in almost the study area. Its depth varies from 4 meters to 30 meters. The reclamation results are composed of loose rock that has not been fully compacted, so it has not been well consolidated. As a result, it will experience land subsidence if overload.

New 3-D Combined Inversion Scheme Using Response Functions Free From Galvanic Distortion

The combined inversion using distortion-free response functions is an effective approach to robustly estimate the 3-D electrical resistivity structure against the distortions caused by near-surface resistivity anomalies. However, previous combined inversion analyses have presented a significant dependency of the inversion results on initial and prior models. Therefore, in this study, we evaluated the effectiveness of the following two new types of 3-D combined inversion using distortion-free response functions: one uses the phase tensor and the vertical and inter-station horizontal magnetic transfer functions, while the other uses the Network-MT response functions, in addition to the former. Because long dipoles are used, the Network-MT response function is negligibly affected by galvanic distortion. To access the combined inversion approach, we developed a novel 3-D inversion scheme combining the response functions of the usual magnetotelluric measurements and the Network-MT response function. The synthetic inversion analysis demonstrated that both of the proposed combined inversions can recover the characteristic resistivity distributions of the target model without a significant dependence on the initial models, at least in the shallow part. These results demonstrate that the combined inversions using only distortion-free response functions have the potential to estimate subsurface resistivity more robustly than what was previously thought. Furthermore, we confirmed that the combined inversion using the Network-MT response function can make the resultant resistivity structure closer to the actual one and enhance the stability of the inversion. This result suggests that the combined use of the Network-MT response function is the preferred approach.

Delineating the characteristics of saline water intrusion in the coastal aquifers of Tamil Nadu, India by analysing the Dar-Zarrouk parameters

Tuticorin, located in the southeastern part of Tamil Nadu, is a coastal aquifer on which Vertical Electrical Sounding (VES) was conducted, thereby analysing the interpreted subsurface resistivity layer parameters covering around 112 km2 area of the study region. VES is an essential tool for investigating hard rock terrains of coastal aquifers and perceive an idea about the groundwater quality. In this study, Dar-Zarrouk (D-Z) parameters like longitudinal conductance (Sc), transverse resistance (Tr) and anisotropy (λ) are analysed as these are well-established parameters in delineating the occurrence and distribution of both fresh and saline water aquifers. These parameters are also very persuasive in investigating complex subsurface parameters (resistivity and conductivity) within saline water intruded coastal region environment. After conducting a thorough survey, the resistivity results reflect that the sediments are enriched with saltwater, clay with moderate freshwater and freshwater-bearing formations. The analysis shows that the D-Z parameters offer a helpful and assured answer in demarcating the saline, moderate fresh, and freshwater aquifers. Therefore, the behaviour and patterns of the D-Z parameters in space established the existence of saline water and freshwater aquifer structures in the coastal aquifers over a vast area.

Identification of lithological units using geo-electrical method, Olabisi Onabanjo University Campus, Southwestern Nigeria

The study presented the results obtained from estimation of the depth to the bsement bedrock (overburden thickness) in Olabisi Onabanjo University, Ago-Iwoye using two configurations of electrical resistivity methods. The study was aimed to delineate the stratigraphy and thicknesses of the subsurface layer present in the study area for comprehensive study of the lithostratigraphic information of the area. Vertical Electrical Sounding (VES) and 2-D Horizontal Electrical Profiling (HEP) techniques were used to obtain 1-D and 2-D subsurface resistivity images of the study area. The VES data were plotted manually on the Bi-log graph. The curve obtained was partially curve – matched to obtain the layer resistivities and thicknesses for further iteration. The 2-D resistivity imaging data were analyzed and processed to obtain the inverted (true) resistivity image. From the results, five (5) VES type curves weredelineated. These includes H, HA, QH and KH type. The geoelectric sections and 2-D resistivity images showed three to four geoelectric layers. These layers are topsoil/laterite, weathered basement, partly weathered/fractured basement and fresh basement. The study showed that materials with resistivity values that ranged between 10 and 298 Ωm and 152 and 589 Ωm representing clayey weathered layer and partly weathered/fractured basement were delineated beneath some sounding points. The clayey and weathered layer are indicative of soil formations that are inimical to foundation of civil engineering structure. Likewise, they can serve as reservoir for groundwater potential (if the porosity and permeability are high). Due to this, detailed lithostratigraphic evaluation through petrophysical analysis is encouraged for the purpose of mapping and correlation of the rock units before embarking on any engineering construction in the study area. The study concludes in providing assistance to subsequent research on the stratigraphic related studies in the area. Keywords: Geo-electric , Stratigraphy, Lithology, Layer,