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

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

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

Reuse of feldspar ore waste after beneficiation for industrial use (Buzlukdaği / Kirşehir / Türkiye)

Feldspar is the most widely used raw material in the ceramic and glass industries. The aim of this article is to investigate the possibility of using flotation process wastes from Buzlukdağı feldspar beneficiation plant as an alternative raw material. The scope of the study includes the evaluation of the use of wastes arising from feldspar enrichment and feldspar processes as alternative raw materials in another process and the investigation of their usability as a final product in various sectors and fields. As a first priority, the Fe2O3 content of the flotation concentrate was reduced to 0.4%. It has been made usable in the glass and ceramic industries. As a second priority, analysis of rare earth elements was made in the wastes formed after the flotation. According to the results of the experiments carried out on the wastes after flotation; demonstrated that it can be used for technological purposes. In addition, it has been determined that the wastes generated as a result of enrichment can be used to provide permeability in urban waste storage areas and hydroelectric dam constructions

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

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

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

Discerning geomorphological aspects of tsunami risk in Pangandaran, West Java, Indonesia

The geomorphological understanding of earth dynamics, including the relationship between landforms and their processes, was one of the earliest and most specific contributions to disaster prevention. Disaster geomorphology is one of the approaches in disaster studies, which includes aspects of landforms, processes, and results of physical processes that have the potential and can cause disasters. The landform is of risk factors that can turn natural hazards into natural disasters and determines the damage that disasters can cause to human activities. Following the 2006 South Java Tsunami, infrastructural development occurred massively in the 2006 South Java Tsunami inundation areas. Several tsunami risk mitigation efforts were conducted but solely based on the 2006 tsunami scenario and ignored the existence of more considerable tsunami hazards from the Sunda Megathrust. This consideration may lead to an increasing risk of future tsunamis. We evaluate and appraise favorable and unfavorable geomorphological features to reduce the risk of future tsunamis. Pangandaran has a unique landform compared to other areas on the south coast of Java, and this landform has the potential to reduce future tsunami risk. Typical landforms studied include coastal plains, alluvial plains, Tombolo, tied islands, and structural hills. The results show that the morphological features of the Tombolo and the coastal plain area are categorized as high risk when a tsunami occurs. The tied island is categorized as a favorable morphology where these morphological units have the advantage of elevation and efficient distance to the tsunami risk zone. Evacuation facilities are also needed, especially in the coastal plain and Tombolo areas (with a height of >20 meters), to reduce disaster risk, particularly mortality caused by tsunami events

Control of Sediment Grainsize on Lead (Pb) Content in the Reef Sediment Systems: A Case Study of Panjang Island, Banten Bay, Indonesia

Sediments are known to accumulate pollutants from terrestrial and coastal waters, and can be used as an indicator to monitor metal pollution in the biosphere and the effects of anthropogenic events in the environment. Eight samples of reef surface sediments were collected from the north and east coasts of Panjang Island.  Panjang Island, located to the north of Banten Bay, was chosen for this study because of its proximity to many industrial areas. Nevertheless, the island supports a natural ecosystem, including coral reefs, seagrass, and mangroves. The samples were analyzed for the grainsize, component analysis, and Pb concentrationusing AAS flame method. The result indicated Pb concentration in the grain-supported surface sediment in Panjang Island is varied. The detected Pb concentrations were 0-28.68 mg/kg in dry weight. The study indicated that the different concentration of Pb value is mainly controlled by the different of sediment grainsize. The highest Pb accumulation occurs in the areas with very fine sediment grainsize, which have better adsorption capabilities for heavy metals. This study also suggests that the medium sand fraction may accumulate different Pb values. The result indicated that, according to the classification of ANZECC/ARMCANZ, all sediment samples in the study area is in the low risk of toxicant level. Additionally, the SQG-Q (Sediment Quality Guidelines) quotient analysis indicates that Pb concentration in the study area posed a low-moderate impact to adverse biological effect