Journal of Applied Geology
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GROUNDWATER VULNERABILITY OF PANDAK AND BAMBANGLIPURO, YOGYAKARTA SPECIAL PROVINCE, INDONESIA
Get PDFThe study of intrinsic vulnerability of groundwater was generated in order to delineate groundwater protection zone in Pandak and Bambanglipuro, Indonesia, whose mainly water supply is from groundwater. Two methods of vulnerability mapping are chosen for the evaluation; DRASTIC method and Hoelting method. The resulted maps conducted from these method are validated using the actual contaminant concentration through the impact of on-site sanitation, for instance nitrate as it is proved to be very stable contaminants in groundwater. Considered in different hydrogeological setting, these two methods have produced various results at the certain site. However, its reliability has been drawn upon the nitrate concentration at the study areas.
Keywords: Intrinsic groundwater, vulnerability, DRASTIC, Hoelting methods, nitrate contaminatio
Concentration of sheep manure bacteria in the immobilization of arsenic from groundwater using zero-valent
No full textPermeable reactive barrier column tests were performed to investigate whether anaerobic bacteria in sheep manure could help remove As from groundwater. One column served as a control and was packed with zero-valent iron (ZVI), compost leaf, wood chips, glass beads, and gravel, after which it was sterilized. The other (‘inoculated column’) was packed with the same ingredients, with the addition of sheep manure as a source of anaerobic bacteria. Simulated As-contaminated groundwater was prepared based on groundwater samples from Sumbawa Island, Indonesia, but with the arsenic concentration adjusted to 50 mg/L. The inoculated column was found to remove As more effectively from the simulated groundwater than the sterilized one. A gradual decrease in sulfate concentration was observed in the inoculated column at the rate of 0.26 mmol of sulfate/L/day, suggesting that there was sulfate-reducing activity in the microbial population. In addition, the sulfur isotope ratio showed -4.3 (‰) and 0.2 (‰) in influent and effluent, respectively, indicating that sulfate-reducing bacteria (SRB) consumed δ32S preferentially. Using population size estimates from the most probable number (MPN) method, the population of SRB was found to increase with distance traveled in the column. Profiling the community composition of the bacteria in different fractions of the inoculated column using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) on 16S rRNA sequences suggested that a majority of bacteria were various Clostridium species and one species of Proteobacteria, Geobacter metallireducens GS-15. Some of them may contribute to the removal of arsenic.Keywords: Sheep manure, zero valence iron, arsenic, immobilization, sulfate-reducing bacteri
Geo-disaster Laharic Flow along Putih River, Central Jawa, Indonesia
Get PDFIn 2011, laharic flow transporting volcanic materials had significantly occurred along Putih River, causing severe damage in Jumoyo area, Magelang, Central Java, Indonesia. The disaster happened frequently until April 2011. The approximately 150 million cubic meter of volcanic materials expelled from 2010 Merapi eruption has been assumed as main cause of recent laharic flow. Although pyroclastic deposit mostly flew to south and southeastern direction through Woro, Gendol, and Opak Rivers, laharic flow apparently flew to the west – westward directions through Putih and Pabelan Rivers. This study will explain the mechanism of such disaster along Putih River from sedimentological point of view.
Transport mechanism of laharic flow along river is strongly controlled by the slope and type of fluids. In the upper stream area, debris flow commonly occurs as gravity flow in the steep slope. To the downstream area, where more river and surface water infiltrates the volcanic material transportation, laharic flow mechanism transforms to hyperconcentrated flow. In the gently slope area, laharic flow decreases in concentration but increase in amount because of the accumulation influx from several river flows. Hyperconcentrated flow in Putih River is mostly generated by accumulation of river flow in the tributary area. In such area, loose volcanic materials are eroded easily by surface water. Rill and gully erosion bring volcanic material into main channel of Putih River, followed by intensive vertical erosion along upper stream that will produce bigger accumulation of volcanic material within laharic flow in the downstream area. Several sabo dams along the Putih River were damaged during early period of laharic flow due to this transportation mechanism.
At the downstream of in Gempol Village, Jumoyo Area, the main channel of Putih River is shifting northwestward significantly due to Gendol Hill. On the other hand, river body in this settlement area is narrower compared to the upper stream area just before turning point. Both condition cause laharic flow to spill out from the channel and form an unconfined sheet debris flow with a 500 m width and around 2-4 m thick sediments. Although energy of transport is reduced significantly, but this flow is still able to transport abundant volcanic material ranging from silt to boulder. Traditional market and hundreds of houses were buried and the main road from Yogyakarta to Magelang city has been disconnected for several times due to this disaster.
Keywords: Putih River, Laharic flow, Jumoy
COASTAL AQUIFER GROUNDWATER MODELING IN THE SOUTHERN PART OF YOGYAKARTA AREA, INDONESIA
Get PDFParangtritis beach, located in a coastal aquifer at the southern part of Yogyakarta Province, Indonesia is bounded by the Indian Ocean at the South, Opak River at the West, and Tertiary Limestone Rock to the East. Local land-use is predominantly agriculture, rice fields and settlements and the population is estimated to be 9,386 persons as per the 2012 census. The total surface area is estimated at 9.46 km2. The aims of this research were to understand the system of groundwater and to assess and predict saltwater intrusion by conducting a numerical groundwater model. Hydrological and hydrogeological data were collected directly from the field and from previous work for input into the model. The model simulates an unconfined aquifer system where the aquifer thickness varies from 30-40 meters. The material of the aquifer consists of sand varying from fine to coarse grain size and fine gravel with hydraulic conductivity values of 8.974 × 10−4, 1.794 × 10−3, and 1.337 × 10−3 m/s at the northern, central, and southern part of the research area, respectively. The maximum length of the saltwater interface was estimated at about 205.1 m laterally and 40 m vertically relative to the location of the groundwater table around 1m above sea level. Direction of groundwater flow is from north to south. Groundwater table elevation equals 5 m at the north and 0 m at the south with a hydraulic gradient estimated at about 2.45 × 10−3. As a result of a steady-state simulation as well as two cases of prediction for five and ten years in the future, it is determined that that the salinity of the surrounding environment is not potentially adverse to the groundwater quality in the study area. This is in part due to low population in this area and abundant groundwater resources, as well as the results of the groundwater model. Keywords: Coastal aquifer, numerical groundwater model, conceptual model, observed head
SITE RESPONSE CHARACTERISTICS OF H/V SPECTRUM BY MICROTREMOR SINGLE STATION OBSERVATIONS AT PALU CITY, INDONESIA
Get PDFIn this study, we estimated predominant period of an H/V spectrum in Palu City, Indonesia, by using microtremor single station observations. Sulawesi Island, eastern Indonesia, is located at the junction between the converging Pacific-Philippine, Indo- Australian Plates and the Eurasian Plate. One of the major structures in Central Sulawesi is the Palu- Koro Fault system, which extends NNW-SSE direction and cross-cuts Sulawesi along more than 300 km from the North Sulawesi trench passing southward through Palu Bay then turn to the southeast, connecting to the Matano and Lawanopo Faults and further eastward both faults join to Tolo trench. Several earthquakes have been known along Palu-Koro Fault system such as Gimpu earthquake (1905), Kulawi earthquake (1907), Kantewu earthquake (1934), and offshore Donggala earthquake (1968) which caused tsunami that destroyed 800 houses and killed 200 people at Donggala district. Palu City, located at the northern tip of Palu depression, is a capital of the Central Sulawesi Province. It is located in the active seismic zone of the Palu-Koro fault. Spectral ratios for horizontal and vertical motion (H/V) from single-station microtremor records were used to identify the predominant periods of the ground vi- brations. Understanding the parameters of predominant period[s] and seismichazard is important for mitigation and environmental planning of the Palu region. Keywords: H/V spectrum, predominant period[s], microtremor single station observatio
DETERMINATION OF NUCLEAR POWER PLANT SITE IN WEST BANGKA BASED ON ROCK MASS RATING AND GEOLOGICAL STRENGTH INDEX
Get PDFIndonesian government through the National Atomic Energy Agency has planned to build a nuclear power plant. One of the proposed sites is in West Bangka Regency, Bangka Belitung Archipelago Province. The engineering geology of this area is, however, not fully understood and requires further investigations. Engineering geology investigations were carried out by assessing the rock mass quality and bearing capacity based on field observation and drilling data. The assessment was conducted using Rock Mass Rating (RMR) and Geological Strength Index (GSI) classification. The rock mass in the study area was divided into four units, namely Units of Sandstone, Granite, Mudstone and Pebbly Sandstone. The RMR and GSI values in the study area are influenced by the parameters of discontinuity space density, the slope of discontinuity orientation, grade of weathering and groundwater conditions. The assessment shows that the Granite Unit has the best quality which is shown by the average RMR value of 53 and GSI value of 66. Based on the average RMR value, the Granite Unit is estimated to have cohesion value between 0.2 and 0.3 MPa, friction angle between 25° and 35°, and allowable bearing pressure between 280 and 135 T/m2. Based on the GSI value, the Granite Unit is estimated to have uniaxial compressive strength value between 1.0465 and 183.8 MPa, tensile strength between (-0.0122) and (-5.2625) MPa, rock mass strength values between 24.5244 and 220.351 MPa, and modulus of deformation within a range of 1.73–86.68 GPa. The Granite Unit is considered to be the most appropriate location for the nuclear power plants. Keywords: Nuclear power plant foundation, geological strength index, rock mass rating, rock mass qualit
WEATHERING STAGE CONTROL OF TUFF AND ITS INFLUENCE TO THE MALINO–MANIPI LANDSLIDE SUSCEPTIBILITY, SOUTH SULAWESI INDONESIA
Get PDFIn 2013 there has been 34 incidents of landslides which cut the roads linking between Gowa and Sinjai off. The purpose of this study was to determine the effect on the stage of weathering of landslide in the study area. Methods used in this study are field survey, petrographic analysis, XRD analysis and shear strength testing of rock. Field survey results indicates that the area is dominated by tuffs that are partly volcanic breccia and lava. Petrographic analysis, showing the dominant composition of tuff with volcanic glass, bitownite, pyroxene and opaque minerals, and XRD analysis results indicate weathering tuffs that have experienced high and completely weathered contain smectite and halloysite clay types, and insitu shear strength test results indicate a strong shift to the lower tuff with high stage of weathering. Keywords: Susceptability to landslides, the stage of weathering, halloysite and smectite, shear strength, roads of Malino–Manip
LANDSLIDE SUSCEPTIBILITY ASSESSMENT OF KOKAP AREA USING MULTIPLE LOGISTIC REGRESSION
Get PDFA number of landslides have occured in Kokap SubDistrict, Kulon Progo Regency, Yogyakarta Special Province, Indonesia, which have influenced the communities. The natural disaster is commonly associated with a few days of heavy rainfall events. To mitigate the impact of landslides in this area, a landslide susceptibility assessment needs to be carried out. The main objective of this research is to develop a landslide susceptibility zonation in the research area by applying a logistic regression (LR) method. Field observation was conducted at 68 locations in the research area, in which 46 landslides occured. Data of slope angle, lithology, geologic structure and groundwater conditions were collected. The relationship between landslide occurrence and the slope angle, lithology, geologic structure and groundwater conditions was analysed using the LR method. The analysis results showed a 0.984 standard error, implying a good-fit model. The study area was classified into very low, low, moderate, high and very high landslide susceptibility zones with 0–20%, 20–40%, 40–60%, 60–80%, and 80–100%, respectively, probabilities of occurrence. A 60% area of the total study area was classified as a moderate to very high susceptibility to landslide. From 47 landslides, 80% landslides occured in high and very high landslide susceptibility zones, 17% landslides occured in the moderate susceptibility zone and 2% landslides occured in the low susceptible zone. None of landslides occured in the very low landslide susceptibility zone. The analysis results show that LR method is a very useful method for landslide prediction. Keywords: landslide susceptibility, multiple logistic regression, Kokap Kulon Progo-Indonesi
CHATODOLUMINESCENCE MICROSCOPIC ANALYSIS TO INTERPRET THE REDOX CONDITION DURING THE FORMATION OF CARBONATE VEIN
Get PDFCathodoluminescence (CL) is generated by an electron gun coupled to an optical microscope. There are two types of chatodoluminescence, i.e., cold CL and hot CL. In the cold cathode microscopic equipment, the electrons are generated by an electric discharge between two electrodes under a low gas pressure, whereas in the hot CL microscope, the electrons are generated by heating a filament (2000–3000°C). In this paper we utilize cold CL combine with electron microprobe analysis (EMPA). The CL microscopy of carbonate shows at least three carbonate generations, i.e., rhodochrosite with dull or no luminescence, Mg-rich calcite with dark red luminescence, manganese-bearing calcite with up to 0.04 wt.% Mn with bright orange luminescence, and pure calcite and Mn-rich calcite (> 0.15 wt.% Mn) with dull or no luminescence. The result also suggests that the luminescence pattern of calcite is controlled by the amount of Mn2+. Sectoral zoning and chevron-shape growth zoning exist in some coarse-grained calcite aggregates. The sectorial zoning of calcite as reflected by dull to bright CL color indicated that slightly to more reducing environment during calcite deposition.
Keywords: Chatodoluminescence, rhodochrosite, calcite, sectorial zonin
Petrogenetic interpretation of granitoid rocks using multicationic parameters in the Sanggau Area, Kalimantan Island, Indonesia
Get PDFGranitoid rock compositions from a range of tectonic environments are plotted on a multicationic diagram, based on major and trace element geochemistry and K-Ar dating. This shows that there is a different tectonic nature, rock affinity and suites. The basement granitoid rocks are ranging from diorite to granite composition. They appear to the products of crystallization differentiation of a calc-alkaline magma of island affinity and range to metaluminous granites, granodiorite and tonalite. The tectonic setting has two kinds which are subduction and post-subduction. The geochemical interpretation, origin and melting of mechanism and tectonic setting shows the types of granitoid are M and I-M type. The basement of granite and granodiorite are a segment of island arc that were happened the Sintang Intrusion as post subduction or syn-collision tectonic setting.
Keywords: Petrogenetic, tectonic, affinity, Sintang Intrusion, Kalimanta