Journal of Geoscience, Engineering, Environment, and Technology
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Hydrodynamics Features and Coastal Vulnerability of Sayung Sub-District, Demak, Central Java, Indonesia
Get PDFThe Sayung sub-district is an abrasion area in Demak Regency that is mostly affected by sea level rise. The purpose of this research is to determine the features of hydrodynamics and coastal dynamics occurrence in the sub-district of Sayung. Collecting field data/information and modeling approach (tides, waves, currents, weather and coastline changes) have been done in Sayung, Demak. The wave height in the eastern coast is the highest. The significant wave height in 2004 was greater than March 2016 showing that in 2004 the wind energy transfers were larger than 2016. The refraction coefficient in 2016 for all directions was the greatest from the west at the depth of 8 m and the smallest one was identified in the south. The refraction coefficient in 2004 for any direction yielded the largest value in the southwest at the depth of 2 m and the smallest one was identified the south as well. During a cycle of tidal fluctuation, it occurs twice flood and ebb events. The maximum depth is 6.5 m located about 3.8 km from the coastline. The sediment thickness reached 564,886.39 m3. Coastline changes occurred in 2003 and started to gain sedimentation in 2015. Data and information produced can be useful as a basis for further developments to mitigate abrasion and to create policy-brief in managing coastline affected abrasion even though some improvement efforts have been made
Disaster Mitigation for Palu City Residents in Dealing with Liquefaction Disasters in Accordance of Spatial Patterns of Palu City, Central Sulawesi Province, Indonesia.
Get PDFPotential natural hazards in Palu City by paying attention to the real physical characteristics of Palu City are categorized as having a high level of disaster hazard. The geological character of both the geological structure and geological engineering in the Palu region shows the great potential for geological disaster hazards. On September 28, 2018, at 18: 02 CIT, an earthquake measuring 7.4 on the Richter scale, the quake's center located in 26 km of Donggala district and 80 km northwest of Palu City. By observing the epicenter's location and the depth of the hypo-central earthquake, it appears that this shallow earthquake occurred due to activity in the Palu Koro fault zone.
This fault is the most active in Sulawesi and is the most active in Indonesia with a movement of 7 cm per year. Liquidity disasters or ground liquefaction are also the effects of an earthquake. Shocks a massive quake causes the soil to melt this thing occurs when the saturated soil loses strength and stiffness due to stress. The Petobo area and the Balaroa - Perumnas are close to the Palu Koro active fault line and the land in the area is composed of soft material from the sedimentation process. This area is shallow groundwater with high soil permeability values, namely in the Petobo area and Perumnas - Balaroa.
The purpose of this study is to analyze the potential liquefaction disaster in Palu City and analyze the Palu City resident ability against Liquefaction Hazard Prone. This research uses a descriptive qualitative analysis method. Potential liquefaction disasters were analyzing qualitatively based on geological conditions and disaster locations. Disaster mitigation capabilities were analyzed qualitatively based on the Palu City Spatial Pattern. One of the hazards caused by an earthquake that has the potential to be a disaster in Palu City is liquefaction.
The ability of residents to mitigate liquefaction in Palu City is influenced by local wisdom which is reflected in ancient times when people lived in the highlands or hills. the concept of building structures, land use, and spatial planning patterns in Palu City which can reduce the threat of liquefaction
Shale Gas Potential In Jambi Sub-Basin, Indonesia: Insights From Geochemical and Geomechanical Studies
Get PDFJambi sub-basin, which is located in South Sumatra, Indonesia has enormous potential of shale gas play. Yet, detailed geological studies are rarely undertaken to understand this relatively new hydrocarbon play concept. This paper presents a combination of geochemical and geomechanical studies with the aim to better understand: (1) the maturity level of source rock; (2) the mechanical properties of shale; and (3) the quality of hydrocarbon source rock. This research began with determination of wells that penetrate the Talangakar and Gumai Formations that have shale in it. Source rock analysis was done by using TOC (total organic carbon), S1, S2, S3, Tmax, and Ro (vitrinite reflectance) data. Geomechanical evaluation was done by using XRD and well logs data. Brittleness index was obtained by using Jarvie et al. (2007) formula, based on the XRD data. S-wave and P-wave are used to calculate the rock strength, Young's modulus and Poisson's ratio with UCS-To methods.Source rock in the Geragai belongs to the of moderate-to-good category because it has more than 0.5% TOC and potentially forms gas because it has a type III kerogen. JTBS-2 well is the only well in the Geragai area which already mature and has been able to produce hydrocarbons, because it passed the oil and gas windows. Source rock in the Betara belongs to moderate-to-good category because it has more than 0.5% TOC potentially forms gas because it has a type III kerogen. Most formations in the Betara are not yet mature based on the value of Ro and Tmax. In wells that have not reached the oil window nor gas windows, the prediction line drawn on the Petroleum Source Rock Summary chart, estimated that they would pass the gas window at Lower Talangakar Formation or Lahat Formation at depth of more than 8000 feet. The results of XRD analysis showed that the Betara had a high brittleness index with an average of 0.809. Talangakar Formation has a higher rock strength values than Gumai Formation, both in Betara high and Geragai deep. The principle that say the rocks which have high TOC values will have a high value of BI can be proven in the study area, the rocks that have high Ro will have a high value of BI, cannot be identified in the study area. With sufficient high value of rock strength and low abundance of clay minerals, the rocks at Talangakar Formation is good for hydraulic stimulation
Association between Surface Air Temperature And Land Use On The Campus Scale
Get PDFThe increasing trend of global temperature is related to the land use change in the form of urbanization. The impact of land use change to surface air temperature in Indonesia especially in smaller scope in Indonesia have not researched yet. The study area is located on newly built campus and the development of land use change inside campus can be managed carefully. This research aim is to determine which land use affecting high-temperature by using multiple linear regression method with least square approach so that temperature increase can be controlled in which some land uses must be preserved in urbanization. Land use data is interpreted from the photo map of 275 hectare campus. Temperature data is measured by using the digital thermometer three times a day. The method idea is to obtain distinctive contribution of every land use to every temperature measurement point. The contribution follows the inverse distance weighted concept. Surface air temperature measurement points are located with 150 meter interval and centroids of land use polygons are used for association calculation. Temperature measurement shows values between 25.5oC and 35.4oC. Land use with more anthropogenic activities and rubber plantation are the top contributors to high surface air temperature within a day. In the non-built-up land use category, water body increases the temperature in the daytime. Anthropogenic activities and vegetation density within land use is the main factor in increasing the surface air temperature so that it is suggested to plant farm-like vegetation around every built-up land use
The Permeability of Granite Weathering Soil in Tanjungpinang, Bintan Island, Indonesia
Get PDFBintan Island is a part of Riau Islands Province. On this island, the capital city is Tanjungpinang. The compliance of public facilities such as landfill waste is a priority in this city. Landfill design that suitable in this area is a sanitary landfill system. The soil layer uses to cover the waste in this landfill system. The closure did gradually avoid the disruption of waste processing. The type of soil for its landfill cover has to be able to control the leachate. It controlled by the permeability of the soil.
The methods used in this study are the analysis of the physical and mechanical properties of soil. Rock and soil samples are obtained systematically through trenching. Sampling-based on changes in physical properties of soil that reflect its mechanical properties. A probabilistic approach used to solve the problems and to get accurate results.
The geomorphology of the study area divided into four units. They are very flat terrain, flat terrain, slightly steep hills, and steep hills. The sample used for the study is undisturbed soil. Analysis of the physical and mechanical properties of soil shows the types of soil, such as SW, GM, MH-OH, and CH. However, MH is the most dominant type of soil. Each of the soil types represents a certain degree of weathering. The degree of weathering in the study area varies from the III degree to VI degrees. Rocks are weathering form clay mineral, which compiles the soil. Clay mineral in the soil layer is varied from quartz, illite, kaolinite, gibbsite, goethite, and hematite—the impact of the swelling of clay. The swelling of clay in the study area ranged from low to high. The properties and composition of the soil are affected by the permeability value
Stream Sediment Geochemical Survey on Metamorphic Rock, Kolaka, Southeast Sulawesi, Indonesia.
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The aim of this research is to conduct surface geological mapping to determine the lithologies that underlies the linear geochemical characteristics of Ag, As, Cd, Co,Cu, Fe, Mn, Ni, Pb, Zn by using stream sediment data. Furthermore, to know the distribution of these elements lithologically in the area. This study uses 10 sediment stream samples of 80 mesh up to 100 mesh which then chemical elements are analyzed with AAS. Alteration mineralization occcurs in quartz chlorite geneiss: quartz, epidote, chlorite, muscovite, sericite, calcite, monmorillonite, pyrite, sphalerite, bornite and chalcopyrite. Based on linearity analysis elements are grouped into three according to the significant value of 0.3 to 0.9, which are significant elements Ni, Pb=Cu=Zn and As, abundant elements in lateralization and sulphide mineralization. The geochemical characteristics of the Ni element reflect the associated distribution of ultramafic weathering which results are transported regionally and together with other elements as stream sediments. While Pb, Cu, Zn are related to quartz veins in metamorphic or intrusive rocks
The Role of Decadal Kelvin Wave in the Western of Sumatra and Along the South Coast of Java using Frequency-Wavenumber 2D Spectral Analysis
Get PDFThis study observed the decadal variability of the sea surface height anomaly (SSHA) and identified the decadal Kelvin wave propagation along west-Sumatra and south coast of Java. SSHA data and the vertical distribution of sea temperature for 64 years from HYCOM model resulted has already used in this research. There are several methods to identify the propagation of decadal Kelvin wave. These methods were low-pass filter by cut-off 1 and 8 years, visual analytic by using Hovmӧller diagram method, and frequency-wavenumber 2D spectral analysis to identify the Kelvin wave propagation and its period. The decadal Kelvin wave could be observed in west coast of Sumatra and along south coast of Java. There are three propagations of decadal Kelvin wave and their velocities were 1.029x10-3 m/s (1974 – 1976), 0.21 m/s (1985 – 1986), and 6.86x10-4 m/s for 1998 to 2001 trough west Sumatra and southern Java. The frequency-wavenumber 2D spectral analysis produced the improvement of Kelvin wave and it has the period of 7.25 years. The occurrence of the Kelvin wave has a relation to IOD index. The average of the IOD index when the decadal Kelvin wave was occurring must be the negative value, its value was a -0.21
Rock Physics Formula and RMS Stacking Velocity Calculation to Assist Acoustic Impedance Inversion that Constrain Well Data
Get PDFThis research ilustrate the generation of acoustic impedance inversion in the absence of well log using stacking velocity input in Salawati Basin, Papua, Indonesia using data obtained from seismic lines and stacking velocity section. Initial acoustic impedance modelswere first before the inversion process and were created by spreading the value of well log data to the all seismic CDP. The calculated acoustic impedance logs from standard sonic and density logs were used to build the initial model of acoustic impedance.First, the stacking velocities was first interpolated on a grid that has the same size as the seismic data using by means of Polynomial algorithm. This was closely followed by the conversion of the stacking velocities to interval velocities using Dix’s equation. The matrix densities were estimated by simple rock physics approach i.e. Gardner’s equation as a velocity function. The initial model of acoustic impedance was calculated by multiplying the densities section and interval velocities section. The resulting initial model of acoustic impedance was inverted to obtain the best of acoustic impedance section based on reflectivity