Modeling Microgravity Anomalies That Accounts of the Pore Water Drainage Inferred from The Dc-Resistivity Sounding Data Over a Coal Panel

A microgravity data set presented in a previous study exhibits distinct short-wavelength anomalies over a longwall coal mine panel at Soma-Darkale Coalfield. Nevertheless, our preliminary models suggest that the wavelength after the coal removal from a panel at a moderate depth and fracturing alone should be incomparably greater than that of the measured anomalies. Understanding the mechanism that causes these anomalies usually becomes critical to provide credible evidence for longwall mining-related legal cases. This study improves the model by including the post-subsidence drainage as it occurs because of fracturing that causes an increase in water storage and local density change. Since no water-level information was available at the site, we attempted to infer the drained zone from the dc-resistivity sounding measurements acquired shortly before the gravity field survey. The wavelengths of the model anomalies became reasonably comparable with that of the residual anomalies after the inclusion of the inferred drainage information. This presented approach that does not require water level measurements shows that the inclusion of the inferred drained zone to the model became an amplifying indicator of a coal panel at a moderate depth. Therefore, it may easily find application in settling the mining-related legal cases, understanding the longwall mining-related geohazard, and environmental impact assessments.

Analisa Persebaran Wetland Berdasarkan Metode Geolistrik di Kecamatan Pandak, Kab. Bantul, DIY

ABSTRAKWetland merupakan tanah lunak tersaturasi air yang berada di dekat permukaan yang menjadi permasalahan dalam pembangunan di sekitar daerah penelitian di Desa Gilangharjo, Kab. Bantul, DIY. Oleh karena itu dilakukan pengukuran metode geolistrik untuk mengetahui persebaran kedalaman wetland di sekitar daerah penelitian sebagai bahan kajian pendukung dalam program pembangunan desa. Dalam penelitian ini dilakukan pengukuran metode geolistrik sounding sebanyak lima titik sounding, kemudian data lapangan diproses menggunakan pemodelan inversi 1 Dimensi (1D) untuk mendapatkan kurva model 1D resistivitas batuan. Berdasarkan kurva model 1D resistivitas batuan didapatkan nilai resistivitas wetland berkisar antara 5.66 - 29.6 ohm.m dan kedalaman wetland berkisar antara 0.592 - 2.25 meter yang meningkat ke arah tenggara. kata kunci : Wet soils, resistivitas, geolistrik sounding ABSTRACTWetlands is a soft water saturated rocks in near surface which becomes a problems of developement in surrounding area of Gilangharjo Village, Bantul District, DIY. Therefore, the research with using geoelectrical methods has been conducted to delineating spreading of wetlands depth in surrounding research areas as a supporting data for village developing programs. In this research is conducted sounding geoelectrical methods measurements as much five sounding points, then the field data is processes with using 1D inversion modelling to get 1D resistivity models curve of rocks. Based on 1D resistivity models curve of rocks is obtained wetlands resistivity value is between 5.66 - 29.6 ohm.m and the depth of wetlands is between 0.592 - 2.25 meters which increase to southwest. keywords : Wet soils, resistivity, sounding geoelectric.

A Reconnainsances Study to Delianate Conductive Groundwater Zone Using Resistivity Sounding in Some Part of Kwara State North-Central, Nigeria

From the results, three to four electrostratigraphic layers with resistivity value ranging from 44 to 997 ohm/m and thickness ranging from 0.5 to 39.7 m were observed in the study area. The top loose rocks, the weathered conductive zone, the fractured basement rock and the fresh basement rock of older granite suite were encountered respectively. From this research, it can be deduce that, the thicker top soil and deeper weathered basement rock at the depth of 30 to 45 meters within this area produce a productive site for sitting future borehole. Insufficient groundwater supply in some places leading to scarcity is noticed in VES 10, VES 12 and VES 13. H, I, and A curve types are generally the most common in the area and are typical of basement complex area. Geographical Positioning System tool (model: GPSmap 76CSx), was used to locate the VES points. Fifteen VES points with electrode spacing [AB/2] of 100 meters separation around Ndanaku and environs were undertaken using Schlumberger configuration. IPI 2 Win [1990-2003] Geosoft resistivity sounding software was used to model the field curves from the measured data on the field. Groundwater in the area is regarded as poor due to localized nature of the aquifer and the study aimed at addressing this scarcity of water within the area by studying the conductive zone and knows the aquifer types through resistivity sounding techniques for future drilling.

Permafrost table depth in soils of Eastern Antarctica oases, King George and Ardley Islands (South Shetland Islands)

This study was aimed to investigate the electrical resistivity in soils and permafrost of various ice-free areas of Antarctica and Sub-Antarctica (from coastal Eastern Antarctica oases to Maritime Antarctica). Measurements of electrical resistivity of soil and permafrost strata were performed with a portable device LandMapper. It was found that the permafrost table depth ranged 82 to106 cm in Bunger Hills, 95 to 122 cm in Larsemann Hills, 27 to 106 in Thala Hills, and 89 to 100 cm on King George Island and Ardley Island. Presence (and thickness) of organic layer and influence of snow patches melting were found the main reasons for differentiation of permafrost table depth in the studied ice-free areas. Anthropogenic disturbance at waste disposal sites resulted in more pronounced soil profile heterogeneity and formation of scattered electrical resistivity profiles. Permafrost layer was found less homogenous in the upper part of permafrost strata compared to the lower part. An application of vertical electrical resistivity sounding (VERS) may be very useful for evaluation of active layer thickness in Antarctic environments, especially when they are facing severe anthropogenic influence due to maintaining of numerous Antarctic research stations and logistical operations

Assessment of Soil Electrical Properties in Selected Agricultural Soils of Puchuncaví, Central Chile

Precision agriculture requires a wide sampling procedure to determine the spatial variability of soil properties for adequate assessment of soil state and appropriate recommendations. Electrical geophysical methods (i.e. vertical electrical resistivity sounding) allow performing rapid measurement of soil electrical properties directly from the soil surface to any depth without any mechanical disturbance of soil cover. Soil electrical properties are linked with many soil properties and could improve the quality and spatial coverage of soil surveys. The results obtained in our study using vertical electrical resistivity sounding confirmed the hypothesis of a high correlation between electrical resistivity and such soil properties as carbon and nitrogen content and silt content. The highest correlation (r > 0.9) was found for electrical resistivity and carbon content. It was also confirmed that significant correlations between electrical resistivity and soil properties are found mainly when soil properties are highly ranged. Perspectives for the applied method lie at the relationship between electrical resistivity and soil properties, such as texture class, clay content, carbon content, and cation exchange capacity. The results obtained in this work could be useful for complex precision agriculture, creating maps of agricultural soils, adequate methods of plant growth, and other issues of precision and conventional agriculture.

Evaluation of groundwater supply potential from hydraulic parameters estimated from vertical electrical sounding (VES) in Ikeduru, south east Nigeria

A Vertical Electrical resistivity Sounding (VES) survey was carried out, to study the groundwater supply potential, protective capacity and soil corrosivity of aquifers in Ikeduru Local Government Area of Imo state, Nigeria. A total of ten (10) geoelectric soundings were acquired. Schlumberger electrode configuration was used in acquiring the data. Six to seven geoelectric layers were delineated from the interpreted results, the Aquifers were delineated between the fifth and sixth geoelectric layers, having an apparent resistivity above 1000Ωm, with the highest thick of 69.0m at a depth of 144.0m. Longitudinal Conductance, Hydraulic Conductivity, Transmissivity and Product Conductance range are as followings for the aquifers; 1.720 – 127.000 x 10-3Ω-1, 15.90 – 188.79m/day, 1093.3 – 1097.1m2/day and 2.590 – 252.50 x 10-3 respectively. Inferring from our hydraulic parameters, all the aquiferous zones have very high designation, wwithdrawal of great regional importance of groundwater supply potential and practically noncorrosive, soil corrosivity. 40% percentage of the aquiferous units have very good protective capacity, while for excellent and good protective capacity of the study are is 30%. All the VES points are said to be a very viable potential for safe source for groundwater exploration.

A Comparison between Drilling and Standard Penetration Test (SPT) Data to the Electrical Resistivity Sounding with Schlumberger Configuration in UNS Area

<p>The geophysics test using electrical resistivity method has been conducted in the area of UNS Campus to indicate the lithological of subsurface. This method is categorized as a Non-Destructive Test (NDT) due to the data acquisition is done at the ground level and no destruction during the test, which is more advantageous than destructive method such as drilling and SPT test. This study was performed with Schlumberger configuration in three location by electrical resistivity sounding. The acquisition data uses Resistivity meter OYO 2119 McOHM-EL with the track length is 100 m, while the data processing use IPI2Win to get a logarithmic graph between distance and resistivity and Origin to obtain graphic of resistivity and SPT. The result of this study indicates that electrical resistivity has a good correlation with SPT data. The electrical resistivity graph shows a linear increase along with increment of the depth, which is similar to the SPT graph. The slope difference at the first location is 2.44±1,197, the second location is 2.028±0.822, and the third location is 0.622±0.735.</p>