scholarly journals Interpretation of 2D-Subsurface Resistivity Data in The Iron Ore Prospect Area of Eastern Binangun Coastal, Regency of Cilacap, Central Jawa

2018 ◽  
Vol 3 (4) ◽  
pp. 214
Author(s):  
Muhammad Sehah ◽  
Sukmaji Anom Raharjo ◽  
Fajar Destiani
Keyword(s):  
Iron Ore ◽  
Fine Sand ◽  
Distribution Patterns ◽  
Research Area ◽  
Magnetic Method ◽  
Clayey Sand ◽  
Resistivity Data ◽  
Resistivity Method ◽  
Interpretation Process ◽  
2D Resistivity

Interpretation of 2D-subsurface rock resistivity data has been carried out in the iron ore prospect area of Eastern Binangun Coastal in ​​Cilacap Regency, Central Java. The background of this research is the potential for abundant iron sand in this area that prospects to be exploited. The research was conducted using a magnetic method in 2017 to map the distribution patterns of the local magnetic anomalies that were interpreted to originate from the distribution of iron ore in the subsurface. In 2018, the research continued using the 2D-resistivity method to find out the lithology section in the subsurface of research area. 2D-resistivity data acquisition is carried out on four tracks consisting of Bng-01 to Bng-04. The resistivity data modeling have produced the true resistivity value for each track in the form of the subsurface resistvity section, which including the Bng-01 track is 2.27 – 44.1 Ωm; the Bng-02 track is 4.5 – 58.6 Ωm; the Bng-03 track is 6.37 – 63.4 Ωm; and the Bng-04 track of 4.98 – 83.3 Ωm. After interpretation process, some models of subsurface rocks lithology section is obtained under the four trajectories. The rocks resulted from interpretation process consists of sand which inserted with gravel (> 58.6 Ωm); sand containing iron ore grains (28.2 – 83.3 Ωm), clayey sand (11.1 – 32.9 Ωm), sandy clay (4.98 – 13.5 Ωm), and fine sand which intruded by saltwater (<6.49 Ωm). Sand containing iron ore grains is main part of the coastal aquifer so that exploitation of iron sand has the potential to reduce aquifer function in storing and flowing of groundwater and causing of abrasion in the Eastern Binangun Coastal area.

scholarly journals Coastal Hydrogeological Model in the Iron Ore Prospect Area of Widarapayung Coastal, Cilacap Regency Based on 2D-Resistivity Data

2018 ◽  
Vol 8 (2) ◽  
pp. 71
Author(s):  
Sehah Sehah ◽  
Sukmaji Anom Raharjo ◽  
Abdullah Nur Aziz
Keyword(s):  
Large Scale ◽  
Iron Ore ◽  
Salt Water ◽  
Shallow Aquifer ◽  
Mining Activities ◽  
Hydrogeological Model ◽  
Clayey Sand ◽  
Deep Aquifer ◽  
Resistivity Data ◽  
2D Resistivity

The coastal hydrogeological model of iron ore prospect area in Widarapayung coastal, Cilacap Regency, has been designed and performed based on the 2D-resistivity data. The background of this research is potentiality of iron sand in this area and its prospect to be mined. Mining activities in large-scale may lead into surface decreasing, triggering damage to the aquifer, abrasion, and saltwater intrusion in the coastal area. The acquisition of 2D-resistivity data has been performed on five trajectories including of WP-01 up to WP-05. Based on the modeling results, it can be concluded that the sub-surface rocks resistivity profile consists of WP-01 with the values of 1.93-114.00 Ωm; WP-02 with the values of 3.67-121.00 Ωm; WP-03 with the values of 3.86-78.40 Ωm; WP-04 with the values of 1.79-100.00 Ωm; and WP-05 with the values of 2.61-86.20 Ωm. After interpretation, it is found that the hydrogeological profile of sub-surface rocks consists of sand inserted with gravels (topsoil); sand containing iron ore granules inserted with silt (topsoil and shallow aquifer); clayey sand (semi-aquifer layer); sandy clay (semi-impermeable layer); and sand (deep aquifer which is intruded by salt water). Based on the analysis, the sand containing iron ore is part of the shallow aquifer, so the mining activities of iron sand is potential to damage and reduce aquifer function in storing and flowing the groundwater in the research area.

scholarly journals Designing Aquifer Model for the Banks of the Serayu River, Sokawera, Somagede, Banyumas, Indonesia by Means of 1D-Electrical Resistivity Data

2021 ◽  
Vol 53 (3) ◽  
pp. 344-357
Author(s):  
Sehah Sehah ◽  
Hartono Hartono ◽  
Zaroh Irayani ◽  
Urip Nurwijayanto Prabowo
Keyword(s):  
Electrical Resistivity ◽  
Model Potential ◽  
Research Area ◽  
Shallow Aquifer ◽  
Shallow Aquifers ◽  
Clayey Sand ◽  
Deep Aquifer ◽  
Resistivity Data ◽  
Deep Aquifers ◽  
Groundwater Aquifer

A geoelectric survey using the 1D-electrical resistivity method was applied to design a groundwater aquifer model for the banks of the Serayu River in Sokawera Village, Somagede District, Banyumas Regency, Indonesia. The aim of this research was to identify the characteristics of aquifers in the research area based on resistivity log data. Acquisition, modeling, and interpretation of resistivity data were carried out and the results were lithological logs at seven sounding points. Correlation between the lithological logs resulted in a hydrostratigraphic model. This model is composed of several hydrological units, i.e. shallow aquifer, aquitard, and deep aquifer. The shallow aquifers are composed of sandy clay (10.81-18.21 Wm) and clayey sand (3.04-7.43 Wm) with a depth of groundwater from the water table to 27.51 m. The deep aquifers are composed of sandstone with variation of porosity (2.24-12.04 Wm) at a depth of more than 54.98 m. Based on this model, potential shallow aquifers were estimated to be at sounding points Sch-5, Sch-6, and Sch-7. This hydrostratigraphic model shows that the two types of aquifers are separated by an aquitard layer, allowing groundwater infiltration from the shallow aquifer to the deep aquifer and vice versa. Moreover, the Serayu riverbanks in this research area are estimated to be a groundwater discharge area.

scholarly journals A Geophysical Survey with Magnetic Method for Interpretation of Iron Ore Deposits in the Eastern Nusawungu Coastal, Cilacap Regency, Central Java, Indonesia

2020 ◽  
Vol 5 (1) ◽  
pp. 47-55
Author(s):  
Muhammad Sehah ◽  
Sukmaji Anom Raharjo ◽  
Azmi Risyad
Keyword(s):  
Magnetic Anomaly ◽  
Iron Ore ◽  
Magnetic Anomalies ◽  
Research Area ◽  
Ore Deposits ◽  
Magnetic Method ◽  
Contour Map ◽  
Strength Data ◽  
Central Java ◽  
Iron Ore Deposits

Geophysical survey with magnetic method to interpret the iron ore deposits in the Eastern Nusawungu Coastal, Cilacap Regency, Central Java, Indonesia was carried out during six month, i.e. March –August 2017, covering the area in the geographical position of 109.3462° – 109.3718° E and 7.6958° – 7.7098° S. This survey has produced total magnetic field strength data at each measuring point in the research area. The magnetic field strength data which have been obtained, then be processed, corrected, and mapped so that the local magnetic anomaly contour map can be obtained. The local magnetic anomaly contour map shows the distribution of magnetic anomalous sources in the subsurface of research area. The 2D-modeling of magnetic anomalies data has been carried out along the AB trajectory extending on the local magnetic anomaly contour map from the position of A(109.3463°E and 7.7023°S) to B (109.3688°E and 7.7053°S), so that some subsurface anomalous objects is obtained. The modelling results of magnetic anomalies data show that the research area is estimated to have the potential of iron ore deposits. The subsurface rocks deposits containing iron ore are estimated to be located below the AB trajectory with a length about of 164.85 meters, a depth ranging of 1.709 – 31.909 meters, and a magnetic susceptibility value of 0.0122 cgs unit. These rocks are interpreted as sand deposits which coexists with silt and clay containing iron ore grains from the alluvium formation. Further, iron ore is also estimated to be present in the rocks deposits below the AB trajectory which have a depth of 24.405 – 49.809 meters and 3.989 – 11.111 meters, with the magnetic susceptibility values of 0.0093 and 0.0073 cgs units.

scholarly journals A Resistivity Survey of Phosphate Nodules in Oshoshun, Southwestern Nigeria

2018 ◽  
Vol 65 (2) ◽  
pp. 103-114 ◽  
Author(s):  
Oluseun Adetola Sanuade ◽  
Abayomi Adesola Olaojo ◽  
Adesoji Olumayowa Akanji ◽  
Michael Adeyinka Oladunjoye ◽  
Gabriel E. Omolaiye
Keyword(s):  
Electrical Resistivity ◽  
Apparent Resistivity ◽  
Inversion Algorithm ◽  
Clayey Sand ◽  
Southwestern Nigeria ◽  
Resistivity Data ◽  
Resistivity Method ◽  
Dahomey Basin ◽  
Geophysical Study ◽  
Electrical Resistivity Method

Abstract This geophysical study was carried out to determine the occurrence of phosphate nodules in the Oshoshun Formation of the Dahomey Basin, Southwestern Nigeria. The electrical resistivity method, comprising 1D vertical electrical sounding (VES; using Schlumberger array) and 2D geoelectrical imaging (using Wenner array), was used to determine the nature and depth of occurrence of the phosphate nodules. Six profile lines were established within the study area, and inverted sections were generated from the apparent resistivity data using DIPRO inversion algorithm. Five VES points were also acquired in the study area, and Win- Resist programme was used to process and interpret the field resistivity data. Four pits were dug along the profiles to verify the interpreted results. The results obtained by both techniques reveal similar geoelectric units: the top soil, clay, clayey sand and clay at different depths. These layers host pockets of phosphate nodules (78-≥651 Ωm) with varying thicknesses. The strong correlation between the lithology profiles obtained from the pits and the interpreted results of the inverted apparent resistivity sections demonstrates the efficacy of the electrical resistivity method in characterising phosphate occurrence within the formation.

Uncertainties Analysis of Electrical Resistivity Tomography

2021 ◽  
Author(s):  
Yonatan Garkebo Doyoro ◽  
Chang Ping-Yu ◽  
Jordi Mahardika Puntu
Keyword(s):  
Model Resolution ◽  
Resistivity Data ◽  
Resistivity Method ◽  
Resistivity Model ◽  
2D Resistivity Imaging ◽  
Model Set ◽  
Different Depths ◽  
Measured Resistivity ◽  
2D Resistivity ◽  
Subsurface Cavities

&lt;p&gt;We examined the uncertainty of the resistivity method in cavity studies using a synthetic cavity model set at six-different depths. Conceptual models were simulated to generate synthetic resistivity data for dipole-dipole, pole-dipole, Wenner-Schlumberger, and pole-pole arrays. The 2D geoelectric models were recovered from the inversion of the synthetically measured resistivity data. The highest anomaly effect (1.46) and variance (24400) in resistivity data were recovered by dipole-dipole array, while the pole-pole array obtained the lowest anomaly effect (0.60) and variance (2401) for the target cavity T&lt;sub&gt;1&lt;/sub&gt;. The anomaly effect and variance were linearly associated with the quality of the inverted models. The steeper anomaly gradient of resistivity indicated more distinct cavity boundaries, while the gentler gradient prevents the inference of the cavity boundaries. The recovered model zone above the depth of investigation index of 0.1 has shown relatively higher sensitivity. Modeling for dipole-dipole array provided the highest model resolution and anomaly gradient that shows a relatively distinct geometry of the cavity anomalies. On the contrary, the pole-dipole and Wenner-Schlumberger arrays recovered good model resolutions and moderate anomaly gradient but determining the anomaly geometries is relatively challenging. Whereas, the pole-pole array depicted the lowest model resolution and anomaly gradient with less clear geometry of the cavity anomalies. At deeper depths, the inverted models showed a reduction in model resolutions, overestimation in anomaly sizes, and deviation in anomaly positions, which can create ambiguity in resistivity model interpretations. Despite these uncertainties, our modeling specified that the 2D resistivity imaging is a potential technique to study subsurface cavities.&lt;/p&gt;

scholarly journals Aquifer Area Investigation Using Resistivity Method in Cikopomayak, West Java, Indonesia

2018 ◽  
Vol 16 (3) ◽  
pp. 19
Author(s):  
Josua Washington Sihotang ◽  
Rodrigo Osvaldus ◽  
Danny Bona Tua Munte ◽  
Nasib Priono ◽  
Febriwan Mohamad
Keyword(s):  
Gamma Ray ◽  
Fine Sand ◽  
Research Area ◽  
West Java ◽  
Aquifer System ◽  
Resistivity Method ◽  
Groundwater Basin ◽  
The Right ◽  
Resistivity Log ◽  
Geoelectric Data

Administratively, the research area is located in around Cikopomayak Village, Jasinga, Bogor, West Java,Indonesia. Based on the Hydrogeological and Groundwater Basin Map, this research area was classied to non-potential groundwater basin. In addition, when the summer comes, the lack of water will be happened around the area. Consequently, the water reserve wasn't enough to fulll the necessity of freshwater. Thus, the research about identifying aquifer location was needed. This research aims to determine the depth and thickness of aquifer for the alternative ways to overcome the problem, particularly, for the Cikopomayak Village. Theresearch used the geophysical method by modeling the several data such as Geoelectric 1-D to know the aquifer location based on the section of medium resistivity value. Then, the geoelectric data was correlated to the borehole drilling data that is Gamma Ray (GR) Log, Spontaneous Potential (SP) Log, Resistivity Log, and the cutting data. Commonly, the most suitable lithology for an aquifer is sandstone because of its good characteristic of permeability and porosity. Logging data result will show the small value of GR log, SP Log lean-ing to the right, and low-value resistivity for indicating the aquifer zone. Based on geoelectric data, the research zone has 3 groups of resistivity value and lithology that are shaly clay-stone and siltstone with low-value resistivity (0-50 ohm.m), sandy claystone, medium sandstone, and coarse sandstone with medium value resistivity (50-150 ohm.m), fine sand-stone, sandy claystone, and andesite with high-value resistivity (> 150ohm.m). The aquifer system in the research area was classied into 3 groups that are aquifer, aquitard, andaquiqlud.

scholarly journals Uncertainty of the 2D Resistivity Survey on the Subsurface Cavities

2021 ◽  
Vol 11 (7) ◽  
pp. 3143
Author(s):  
Yonatan Garkebo Doyoro ◽  
Ping-Yu Chang ◽  
Jordi Mahardika Puntu
Keyword(s):  
High Sensitivity ◽  
Two Dimensional ◽  
Model Resolution ◽  
Resistivity Data ◽  
Resistivity Method ◽  
Resistivity Model ◽  
Measured Resistivity ◽  
2D Resistivity ◽  
Subsurface Cavities

We examined the uncertainty of the two-dimensional (2D) resistivity method using conceptual cavity models. The experimental cavity study was conducted to validate numerical model results. Spatial resolution and sensitivity to resistivity perturbations were also assessed using checkerboard tests. Conceptual models were simulated to generate synthetic resistivity data for dipole-dipole (DD), pole-dipole (PD), Wenner–Schlumberger (WS), and pole-pole (PP) arrays. The synthetically measured resistivity data were inverted to obtain the geoelectric models. The highest anomaly effect (1.46) and variance (24,400 Ω·m) in resistivity data were recovered by the DD array, whereas the PP array obtained the lowest anomaly effect (0.60) and variance (2401 Ω·m) for the shallowest target cavity set at 2.2 m depth. The anomaly effect and variance showed direct dependency on the quality of the inverted models. The DD array provided the highest model resolution that shows relatively distinct anomaly geometries. In contrast, the PD and WS arrays recovered good resolutions, but it is challenging to determine the correct anomaly geometries with them. The PP array reproduced the lowest resolution with less precise anomaly geometries. Moreover, all the tested arrays showed high sensitivity to the resistivity contrasts at shallow depth. The DD and WS arrays displayed the higher sensitivity to the resistivity perturbations compared to the PD and PP arrays. The inverted models showed a reduction in sensitivity, model resolution, and accuracy at deeper depths, creating ambiguity in resistivity model interpretations. Despite these uncertainties, our modeling specified that two-dimensional resistivity imaging is a potential technique to study subsurface cavities. We inferred that the DD array is the most appropriate for cavity surveys. The PD and WS arrays are adequate, while the PP array is the least suitable for cavity studies.

scholarly journals STRUKTUR KOMUNITAS DAN ASOSIASI LAMUN (Seagrass) DI PERAIRAN PANTAI RUA PULAU TERNATE PROVINSI MALUKU UTARA

2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Riyadi Subur
Keyword(s):  
Coastal Waters ◽  
Coastal Region ◽  
Positive Association ◽  
Distribution Patterns ◽  
Research Area ◽  
Negative Association ◽  
Line Transect ◽  
Thalassia Hemprichii ◽  
Marine Life ◽  
Cymodocea Rotundata

AbstrakLamun (Seagrass) merupakan salah satu ekosistem penting diwilayah pesisir yangberperan penting baik secara ekologis dan ekonomis. Keberadaan lamun mendukungkehidupan berbagai jenis biota laut. Penelitian ini bertujuan mengidentifikasi jenis-jenislamun yang berada di perairan pantai Rua, Mengetahui kepadatan, pola sebaran,keanekaragaman jenis, dan dominansi serta asosiasi antara spesies. Penelitian ini dilakukandengan metode garis transek dan kuadrat. Hasil penelitian menunjukkan bahwa terdapat 4jenis lamun di perairan pantai Rua yang terdiri dari Cymodocea rotundata, Enhalusacoroides, Halodule pinifolia dan Thalassia hemprichii. T. hemprichii adalah jenis dengankepadatan tertinggi di perairan Rua yaitu 16,70 ind/m2, serta E. acoroides, memilikikepadatan terendah yakni 5,77 ind/m2. Jenis lamun yang ditemukan di lokasi penelitianseluruhnya memiliki pola sebaran mengelompok dengan keanekaragaman yangdikategorikan rendah yaitu sebesar 1,32, serta indeks dominasi sebesar 0,27. Tipe asosiasilamun di lokasi penelitian yaitu asosiasi positif (+), serta asosiasi negatif (-).Kata Kunci. Struktur Komunitas, Asosiasi, lamun.AbstractSeagrass is a important ecosystems coastal region that is important both ecologically andeconomically . The seagrass supports of various marine life. This study to propose identify thespecies of seagrasses in coastal waters in Rua, Knowing the density, distribution pattern,species diversity, and dominance as well as associations between species. This study wasconducted using line transect and kuadrats. The results showed that there are 4 species ofseagrass in Rua consisting of Cymodocea rotundata , Enhalus acoroides , pinifolia Haloduleand Thalassia hemprichii . T. hemprichii is highest density (16.70 ind/m2), and E. acoroides ,which has the lowest density (5.77 ind/m2). Species seagrass found in the research area allhave clumped distribution patterns are categorized with diversity low at 1.32 , and dominanceindex at 0.27. Type association of seagrass in the location studies is positive association ( + )and negative association ( - ).Key Words:community structur, association, seagrass

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