Journal of Geoscience, Engineering, Environment, and Technology
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Simulation of Time-Lapse Resistivity Method on Sandbox Model to Determine Fluid Changes and Desaturation
Get PDFTime-lapse resistivity method is an implementation of the resistivity method that is executed exactly at the same spot but with various in time. In this study, the technique uses to identify the dynamics of groundwater fluids. The application of the time-lapse resistivity method was carried out by performing a sandbox model simulation that contains layers of rocks with a fault structure. The rock layers consist of tuff, fine sandstone, shale, coarse sandstone, gravel that represents confined and unconfined aquifers. The simulation was achieved by applying the Electrical Resistivity Tomography (ERT) dipole-dipole configuration at the same place, and measurements with 3 different conditions, namely dry, wet conditions filled with 2.5% water and wet conditions filled with 5% water. Data acquisition uses Naniura resistivity meters with a track length of 96 cm. The first measurement results (dry conditions) obtained a range of resistivity values from 3.7 to 168.1 Ω.m, the second measurement (wet conditions filled 2.5% water) obtained the range of resistivity values from 3.3 to 110.8 Ω.m and the third measurement (wet conditions) filled with 5% water the resistivity values range from 1.7 to 91.2 Ω.m. Following the results of time-lapse inversion processing, a larger percentage change in the amount of 5.6% due to water absorption by the surface which then migrates into the inner layer. Whereas the percentage of desaturation ranges is from -3.11 to 0.217 %, refer to Archie’s Law assumes conduction is caused by water content
Effect of Porphyritic Andesite Intrusion on The Formation of Contact Metamorphism Aureole in Selo Gajah Hill Clastic Limestone, Bojonegoro Regency, East Java, Indonesia
Get PDFAt Selo Gajah Hill, Jari Village, Gondang Sub-district, Bojonegoro Regency, East Java there are limestone intruded by porphyritic andesite. The intrusion produces contact metamorphisms in the wall rocks. It is very interesting to study the protolith rock, facies of metamorphism and the zonation of contact metamorphism aureole. This research uses field observation method and laboratory analysis i.e. petrographic analysis. Field observation is conducted by doing geological mapping in the Bukit Selo Gajah area and rock sampling for petrographic analysis. Petrographic analysis aims to describe the texture of the rocks and the percentage of minerals, which will be used to determine the protolith rock, metamorphism facies and the determination of contact metamorphism zone. The lithology found in Mount Selo Gajah from oldest to youngest are clastic limestone with intercalation of marl, marl with intercalation of sandstone, porphyritic andesite intrusions, hornfels, and pyroclastic breccia. Metamorphic rocks on Selo Gajah Hill is the product of contact metamorphism of carbonate rock which was intruded by porphyritic andesite intrusion. The metamorphism facies found in the research area are hornblende hornfels and pyroxene hornfels with the protolith rock is carbonate rocks. Metamorphism zone in Selo Gajah Hill is divided into two zones: The zone closest to the intrusion body is vesuvianite zone or idiocrase zone with a radius of 40-140 m from the outer part of the intrusion body and the monticellite zone with radius ranging from 25 to 75 m from the outside of the vesuvianite zone
Settlement and Capacity Analysis of Land Support Development on Flyover in Large City; Pekanbaru, Indonesia
Get PDFThe study area located on the street of Soebrantas to Soekarno Hatta Street, with the coordinate position of 0 ° 30 ' 0.79 "N 101 ° 24 ' 57.88 "E - 0 ° 30 ' 0.16 "N 101 ° 24 ' 53.17 "E in Pekanbaru City, Indonesia. The development that will Conduct flyovers in this area became the basis of this research. The main study of this research is to find out how an Atterberg's boundaries, compressibility, and the likelihood of a ground decline in drill 1 use the value of N SPT to match with the purpose of this study. Which is (1) to know the large grain size of soil samples, (2) Knowing the value of the liquid limit, the plastic boundary, and the plastic index of the soil samples, (3) Knowing the possibility of land degradation in the research area, (4) Power capacity analysis of ground support (5) Knowing the decline of modeling using the Plaxis 2D method (6) knows the relationship of decreasing values based on NSPT and Plaxis (7) Knowing the relationship of sieve analysis and Attaberg limit with decreased results. Methods of data retrieval have done with soil testing in the field and soil testing in the laboratories. A comprehensive analysis of the grain has done with sieve analysis. Plastic boundary, liquid, and plastic boundary indices with method Attaberg limit. Decreased analysis and Power capacity analysis of ground support with NSPT value tests
Impacts of Population Density for Landuse Assessment in Cengkareng, West Jakarta, Indonesia: Landuse Assessment
No full textEconomic development in Jakarta has been influencing physical and social characteristics of urban area significantly. For recent years, burgeoning population growth occurs as a result of urban development and contributes to the landuse dynamics in a certain area. Cengkareng, is one of the most developed urban areas in Jakarta and has been experiencing such population and landuse dynamics. Its strategic location has turned this area becomen densely-populated. Increasing population density increase land demand, shapes the settlement pattern, and changes the landuse of the area. A study conducted in Cengkareng District has been done to describe how the population density impacts the landuse features for landuse assessment. The method implemented in this study combines quantitative and qualitative to process statistics and satellite imagery to produce data of population density, landuse change, and settlement pattern of the studied area. The study resulted that Cengkareng has experienced such significant landuse change which is dominantly converted into settlement and offices due to rising of population density. Nucleated settlement pattern has taken more area regarding to increased land need over land supply. It becomes serious problem for Cengkareng such aa slum settlements, flood problems, and land subsidence.
Keywords: Landuse change; Population density; Settlement pattern
 
Investigation of Groundwater Potential using Electrical Resistivity Method and Hydraulic Parameters in Lam Apeng, Aceh Besar, Indonesia.
Get PDFLam Apeng is a village with a majority of people living as farmers, which causes the need of water for agriculture is increasing. The water demand in this area continues to increase as the population increases, for various purposes. The objective of this study is to determine the distribution of the groundwater layer using the electrical resistivity method and to determine groundwater potential using hydraulic parameters. This research is conducted using 2 measurement line with a length of each line is 112 meters and distances of each electrode is 2 meters. The data invert using Res2Dinv software to obtain 2D subsurface lithology subsurface. At line 1, the aquifer (sand) layer is located in the second layer with a rock resistivity value of 12 Ωm - 18.6 Ωm at a depth of 8 m - 18 m. At line 2, the aquifer (sand) layer is also located in the second layer with a resistivity value of 4.6 Ωm - 18 Ωm at a depth of 5 m – 12 m. Based on the interpretation of the two measurement lines, it can be concluded that the type of aquifer in the research site is a semi unconfined aquifer. In this study, hydraulic parameters (hydraulic conductivity, longitudinal conductance, transverse resistance, and transmissivity) was calculated based on the resistivity value and the thickness of the aquifer layer. The average resistivity of the aquifer layer used is 15.3 Ωm and 11.3 Ωm, respectively for line 1 and line 2, indicating that the aquifer was moderately corrosive. Longitudinal conductance values are 0.65 Ω-1 and 0.62 Ω-1 which indicated moderate protective capacity. The transmissivity values are 6.78 m2/dayand 4.77 m2/day, which indicates that the designation in this area is low and the groundwater potential is local or only for personal consumption
A Geophysical Survey with Magnetic Method for Interpretation of Iron Ore Deposits in the Eastern Nusawungu Coastal, Cilacap Regency, Central Java, Indonesia
Get PDFGeophysical 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