ADAPTIVE PRECONDITIONING KRYLOV SUBSPACE METHODS FOR EFFICIENT NUMERICAL GROUNDWATER FLOW MODELING IN STEADY-STATE CONDITIONS

The numerical method plays an important role in groundwater flow modeling to solve linear equations with sparse matrices. This study evaluates the performance of the Krylov Subspace method with adaptive preconditioning compared to classical iterative methods, such as Gauss-Seidel, Jacobi, and Successive Over-Relaxation (SOR), in the simulation of steady-state groundwater flow on a 2D grid. The results show that the Krylov method with adaptive preconditioning provides the fastest execution time (0.0054 seconds) with minimal resource usage, such as CPU of 0.0% and RAM of only 0.175 MB. In contrast, the classic iterative method shows longer execution times and greater resource consumption. This study concludes that the Krylov Subspace method with adaptive preconditioning is the best solution for applications that require high efficiency in groundwater flow computin

FACIES ANALYSIS AND SEDIMENTATION MECHANISM OF VOLCANICLASTICS OF CIKARANG MEMBER OF JAMPANG FORMATION IN WEST JAVA

The Cikarang Member of Jampang Formation is one of basin fills of the Bogor Basin that is characterized by gravity flow deposits. The variations of lithologies with an abundance of volcaniclastics are found in the Tonjong River in Bojongkalong Village and indicate differences in facies and sedimentation mechanisms. We measured stratigraphy of the rock units supported by petrographic analysis and paleontological analysis. The rock units consist of 11 lithofacies: graded gravel (g1G), massive gravel (m1G), massive gravelly sand (mGyS), plane-stratified laminated sand-mud couplets (slSM), massive gravel-sand couplets (mGS), plane-stratified laminated to graded mud-sand couplets (slgMS), massive sand (mS), plane-stratified gravel-sand couplets (sGS), plane-stratified laminated muddy interval sand-mud couplets (sleSM), plane-stratified laminated muddy interval mud-sand couplets (sleMS), and slump and slide deposits gravel (sdG). The depositional environment of the Cikarang Member is inner-middle fan with changes in depositional sub-environment variations in the form of channels, sandy lobes, silty-sandy distal lobes, and proximal levees with constant paleobathymetry in the lower-middle bathymetry. The volcaniclastics of the Cikarang Member of Jampang Formation is deposited in a turbid mechanism due to a turbulent current with various cohesive debris flows (mudflows) and turbidity currents scattered in each facies association

LANDSLIDE SUSCEPTIBILITY ZONATION USING WEIGHT OF EVIDENCE METHOD IN MERTELU AND TEGALREJO, GEDANGSARI, GUNUNGKIDUL, SPECIAL REGION OF YOGYAKARTA, INDONESIA

Mertelu and Tegalrejo are situated in the Gedangsari Subdistrict, Gunungkidul Regency, Special Region of Yogyakarta, Indonesia. Located in the northern Baturagung Range, Southern Mountains Zone of East Java, with much hilly topography and mountainous areas with steep slopes, Mertelu and Tegalrejo are prone to landslides. The purpose of this research is to produce a landslide susceptibility zone using the weight of evidence (WoE) method. There were 73 landslide data taken from December 2022 to January 2023. As much as 80% of the data were used as a training dataset for weighting and generating the model map, while the remaining 20% were used as a test dataset. Parameters used in this research include slope angle, lithology, distance to faults, distance to rivers, and land use. Each parameter was weighted using the WoE method, and then the map of each parameter was overlaid to produce a map of landslide susceptibility zones. The accuracy of the map was calculated using the area under curve (AUC) method, including the success rate curve (SRC) and prediction rate curve (PRC). Based on the research results, the landslide susceptibility zone in the research area can be categorized: (1) very low, covering 6.34% of the total research area, (2) low, covering 24.15% of the total research area, (3) moderate, covering 44.46% of the total research area, and (4) high, covering 25.05% of the total research area. The landslide susceptibility map shows that the research location is predominantly characterized by areas with medium to high susceptibility to landslides. The medium and high susceptibility zones are close to the rivers that serve as the alignment of the faults. The accuracy calculations result in an SRC value of 0.753 and a PRC value of 0.780, both can be classified as “good” performance

A SYSTEMATIC REVIEW OF GEOLOGICAL RESOURCE CONTAINING NICKEL : RESOURCE, DISTRIBUTION, MINING, EXTRACTION AND ADVANCED MATERIAL SYNTHESIS

Nickel ore is the main source of nickel, an important metal used in many modern materials. This paper gives a brief overview of different aspects of nickel ore, such as its history, types, distribution, demand, and the technology used for mining and processing it. The two main types of nickel ore are nickel sulfide ore and laterite ore. Indonesia has significant nickel ore deposits, primarily in the form of laterite, due to its tropical climate with high temperatures and rainfall. Nickel is essential for making various important materials like stainless steel, special alloys, plating, and batteries. Laterite also contains other valuable elements like iron, magnesium, silicon, and oxygen, found in compounds such as goethite, nickel oxide, magnesium silicate, and quartz. Laterite ore can be processed to produce nickel matte, ferronickel, and nickel pig iron. The paper also discusses advanced materials made from laterite ore, including photocatalysts and batteries. Mining and processing activities have both positive and negative effects on local communities. To minimize negative impacts, it is important to consider the satisfaction of both the local community and the government in the initial planning of mining and processing projects

Geochemical characteristic of volcanic rocks in the Karaha – Talagabodas fields related to Galunggung Volcano

The Karaha-Talagabodas field is located on the east side of the ancient Bandung-Garut caldera and adjacent to the Galunggung volcano in West Java, Indonesia. Karaha-Talagabodas are two distinct locations separated by approximately 10 km. Geochemical analysis including major, trace and rare earth elements has been done using Fusion ICP-MS to find out how the different composition of volcanic rocks in the two regions (Karaha and Talagabodas). The volcanic rocks of the Karaha-Talagabodas field were composed of pyroxene andesite, andesite basaltic, basalt, highly altered pyroclastic and tuff breccia. The identified alteration minerals are indicated by the presence of kaolinite, halloysite, silica, sericite and chlorite. Geochemically, these volcanic rocks contain SiO2 variable (49.94%-62.27%), Na2O (3.02%-3.83%) and K2O (0.46%-1.78%). Based on the major element diagram of rock chemistry (Na2O+K2O vs SiO2). It shows rocks consisting of calc-alkaline for andesite from Karaha basalt, basaltic andesite and andesite formed in tholeiitic environments on Talagabodas volcanic rocks. Trace element data for host volcanic rocks are provided by this study to identify the magmatic arc system and distribution of subduction components. The normalized REE diagram of N-Morb shows the similarity of the pattern of all Talagabodas volcanic rocks, only Karaha andesite rocks show slight REE enrichment and europium depletion

Open-Pit Coal Mine Drainage System Design at PT XYZ, Central Kalimantan

ABSTRACT The purpose of implementing a mine drainage system is to ensure that mining activity areas are not flooded during the rainy season. The mine drainage system in this study consisted of designing sump dimensions, open channels, settling ponds, and pumping and piping systems. The planned rainfall is calculated using the maximum daily rainfall from 2003 to 2022, using the Log Pearson Type III method. The result of the calculation of the planned rainfall is 194.50 m/day. The total discharge of runoff water in the study area was 17.05 m3/s, and the volume of rain was 293,976.94 m3. The sump is designed based on KEPMEN ESDM 1827 K/30/MEM/2018 so that it can accommodate a volume of incoming water of 823,392.60 m3. The pumps used to remove water from the sump to the settling pond are six Multiflo 420 EXHV RPM 1550 pumps. The pipe used is polyethylene with the type HDPE PN 16 PP 100 and requires a length of 908.42 m. The pump capacity discharge is 1,255.40 m3/s with a total head loss of 138.89 m. The channel has discharge capacity of 2.40 m3/s. The settling pond consists of three compartments designed to accommodate a volume of 61,245.20 m3 of water. ABSTRAK PT XYZ merupakan perusahaan pertambangan batubara yang menerapkan metode open pit. Tujuan penerapan sistem penyaliran tambang yaitu agar daerah aktivitas penambangan tidak tergenang air ketika musim penghujan. Sistem penyaliran tambang pada penelitian ini terdiri dari perancangan dimensi kolam penampungan, paritan, kolam pengendapan, dan sistem pemompaan serta pemipaan. Curah hujan rencana dihitung menggunakan curah hujan harian maksimum mulai tahun 2003 hingga tahun 2022 menggunakan metode Log Pearson Type III. Hasil perhitungan curah hujan rencana sebesar 194,50 mm/hari. Total debit air limpasan di wilayah penelitian diperoleh sebesar 17,05 m3/detik dan volume hujan sebesar 293.976,94 m3. Kolam penampungan dirancang berdasarkan KEPMEN ESDM 1827 K/30/MEM/2018 tentang Pedoman Pelaksanaan Kaidah Teknik Pertambangan yang Baik, sehingga mampu menampung volume air masuk sebesar 823.392,60 m3. Pompa yang digunakan untuk mengeluarkan air dari dalam kolam penampungan menuju ke kolam pengendapan yaitu pompa Multiflo 420 EXHV RPM 1550 sebanyak 6 unit. Pipa yang digunakan adalah polietilen jenis HDPE PN 16 PP 100 dengan panjang 908,42 m. Debit kapasitas pompa sebesar 1.255,40 m3/detik dengan total julang yang diperoleh sebesar 138,89 m. Paritan memiliki kapasitas debit sebesar 2,40 m3/detik. Kolam pengendapan terdiri dari 3 kompartemen yang dirancang mampu menampung volume air sebesar 61.245,20 m3

Assessing the Water Criticality Index of the Welaran Watershed in Kebumen Geopark, Central Java: Towards Good Water Resource Management

The water criticality index (WCI) is the ratio between water use and availability. The higher the WCI value, the more concerned the water conditions in the area will be. The water crisis can be handled if various parties manage water resources following good management. The Welaran area is a watershed that is part of the Lukulo Watershed, where the population often experiences water shortages. Therefore, by knowing the value of WCI, it is hoped that various parties can know the water conditions in this watershed. Based on research and calculation of the water balance in the Welaran Watershed, it is known that with total water needs in 2019-2020 of 746,937 m3 and total water availability of 1,555,318 m3, the WCI value of the Welaran Watershed is 48.02%. In 2020, Karangsambung was designated as a part of Kebumen Global Geopark, which will certainly increase the number of tourists visiting here. The increase in tourist visits will also increase the need for water, including in the Welaran Watershed. To overcome these conditions, the Kebumen regency’s government and stakeholders are expected to be able to formulate a water management step by effective management

The origin of Baribis Fault and its relationship to the dynamics of Sunda Arc

Based on analyses of published geological cross sections along the Baribis Fault, we briefly review several possible mechanisms of this backarc thrust that developed behind the volcanic arc in western Java. There is no general agreement regarding the mechanisms of the backarc thrust. Therefore, the origin of this fault remains uncertain. Previous works proposed that the backarc thrust in western Java may have developed as deformation of paleo-accretionary wedge sediments behind a continental backstop, inverted normal fault, northward migrating thrust belt, and thrusting due to gravitational sliding of the volcanic arc. However, evidences supporting those mechanisms still need to be elucidated. Detailed examination of the available geological data might suggest that backarc thrusting in western Java may have formed due to stress transfer through rigid arc blocks. The far-field stress from the subduction zone is propagated through remnants and modern volcanic arcs and finally, deformed sediments in the Bogor Trough that nucleated as backarc thrust