Boy Yoseph

In tropical-volcanic-dominated areas, such as Java Island in Indonesia, aquifer recharge is highly impacted by rainfall intensity and soil characteristics. The first stage of recharge begins with the soil surface's response to rainwater until it percolates to the deep layer. The primary objective of this research was to study groundwater recharge processes from the soil surface to deep percolation in the volcanic deposit at the northwest flank of Mount Pangrango, West Java, Indonesia. The present study also includes the 2D geoelectrical survey results combined with the soil core drilling. A vertical undisturbed soil profile 4 to 4.5 meters deep was drilled to determine parameters such as soil water content, total porosity, permeability, organic content, and soil texture. Results from core drilling activities confirmed that resistivity values are in the range of 80 to 360 ohm.m, which is related to wet soil layers at 1 to 4 meters below the surface. It is found that the most sign...

Groundwater studies were carried out in the center of the West Progo Dome, at Kaligesing, Purworejo District, Central Java, and its surrounding area, with an emphasis on hydrochemical problems. As a water-scarce area, groundwater studies are urgently needed in this area. This research is intended as a hydrogeological study with the aim of knowing the conceptual groundwater flow model in the study area. The method used is a field hydrogeological survey as well as hydrochemical and natural isotope analysis supported by chemical and groundwater isotope data. Less clear hydrochemical evolution indicates that the process of groundwater flow is dominant in the local flow system. Groundwater facies is dominated by bicarbonate type, neutral pH, relatively low total dissolved solid (TDS), and electric conductivity (EC), and influenced by season or rainfall. The dominant hydrochemical processes in the groundwater system are leaching, ion exchange, sulfate reduction, and dilution. Groundwater ...

Studi sistem akuifer hidrogeologi sangat penting untuk dilakukan dalam rangka mengidentifikasi kondisi geologi dan hidrogeologi. Lokasi daerah penelitian termasuk ke dalam daerah bukan cekungan air tanah, tetapi kondisi visual di lapangan menunjukkan penduduk sekitar banyak memanfaatkan air tanah cukup besar. Metode yang digunakan berupa penyelidikan geologi, geolistrik 2-D konfigurasi Wenner – Schlumberger dan hidrogeologi. Tujuan dari penelitian ini yaitu mengetahui sistem akuifer  daerah Sukamoro.  Di daerah Sukamoro terdapat dua sistem akuifer, yaitu pada endapan rawa (satuan lanau) berupa sistem dengan aliran antar butir; merupakan sistem airtanah tidak tertekan, dengan nilai TDS yang acak dengan nilai resistivitas di bawah 40 Ohm meter, berada pada bagian Selatan daerah penyelidikan. Pada satuan perselingan batupasir dengan batulempung yang memiliki sistem akuifer dengan aliran melalui ruang antar butir dan rekahan, merupakan sistem airtanah tidak tertekan dan tertekan,  denga...

Penelitian ini bertujuan untuk mengetahui evolusi hidrotermal dari fluida pembawa mineralisasi yang terdapat di Pit Ramba Joring, meliputi temperatur, tekanan, densitas dan kedalaman pembentukan mineralisasi. Penelitian ini menggunakan analisis inklusi fluida. Sampel yang dianalisis merupakan sampel yang terindikasi terbentuk bersamaan dengan mineralisasi bijih (syngenetik), pada dua tekstur utama bijih yaitu batuan dengan tekstur silica vuggy yang terbentuk pada kisaran Th 331ºC hingga 394ºC, Tm -15,19ºC hingga -12,94ºC dengan salinitas 14,42 wt% hingga 14,89 wt%. NaCl equivalent dan batuan dengan tekstur brecciated terbentuk pada kisaran Th 287,8°C hingga 398,2°C, Tm -14,89°C hingga -11,76ºC serta salinitas 13,91 wt% hingga 4,87 wt%. NaCl equivalent. Korelasi positif antara temperatur homogenisasi pembentukan mineralisasi dengan salinitas larutan menandakan bahwa proses leaching yang membentuk rongga pada batuan terjadi pada stage awal proses alterasi hidrotermal yang diawali deng...

In general, volcanoes have water storage capacity, therefore the groundwater flow system in the volcanic are plays an important role in the study area. Hydro-chemical and stable isotopes methods have been a popular tool for groundwater research. The aims of this study is to assigned the groundwater flow system and examines the quality of groundwater based on hydro-chemical and stable isotopes data. At least, nineteen (19) of groundwater samples were collected at elevations ranging from 126 to 688 m above sea level for hydro-chemical analyses. The pH groundwater is basically neutral and EC values range from 5.0 to19.0 mS/m. Results from chemical analysis were plotted on a piper diagram and all samples fell in the same Ca-Na and HCO3 corner. The groundwater samples were plotted close to the global meteoric water line (GMWL), implying that they are of meteoric water origin.

Deposit Ramba Joring merupakan bagian dari wilayah Kontrak Karya (KK) pertambangan umum PT Agincourt Resources yang terletak di Kelurahan Aek Pining, Kecamatan Batangtoru, Kabupaten Tapanuli Selatan, Provinsi Sumatera Utara. Penelitian ini bertujuan untuk mengetahui kondisi geologi meliputi geomorfologi, stratigrafi dan struktur geologi serta karakteristik bijih yang mengandung emas-perak pada deposit Ramba Joring. Penelitian dilakukan pada 44 lubang bor dan 15 conto permukaan. Penelitian menggunakan metode analisis petrografi sayatan tipis dan poles, Analytical Spectral Devices (ASD), Scanning Electron Microscopy with Energy Dispersive (SEM EDS) serta pengolahan statistik data geokimia assay berupa nilai kadar kandungan Au, Ag, Cu, SxS (sulfide sulphur) yang didapatkan melalui analisis Atomic Absoption Spectrometry (AAS). Daerah penelitian tersusun oleh litologi, diurutkan dari tua ke muda, berupa satuan andesit hornblende dan breksi polimik-monomik. Satuan batuan andesit hornblend...

Banjarsari Village, of Cangkringan Sub District, Sleman Regency, Special Region of Yogyakarta (110°28’04” E, 7°39’11” S), in the geomorphological system, is known as the middle volcanic slope located in the southern area of Merapi Mount, as it is formed by the pyroclastic and lahar deposits. Such condition is attributed to the emergence of sand and stone quarries at many points. On this account, this research aims to identify the potency and type of mass movement on the sand-stone quarry deposits, in order to determine the best mitigation endeavor against the mass movement disaster. Methods of research in use are direct field observation, measurement of the type and position of the stratification, and slope dimension. Furthermore, soil mechanic laboratory analysis was done to the soil sample, consisting of bulk density of the soil (γ), cohesion parameter (c) and friction angle (Ø). The analysis of Safety Factor (FS) was done by using Geo-Slope version 9.0.3 software, aiming to define its stability class. This research resulted in 2 potential locations of a mass movement with debris slide type. According to the analysis of slope stability on the two location, it was revealed that these slopes were categorized into the unstable class with FS= 0.799, in the pyroclastic deposits and for the other location the slope was categorized into the critical classes with FS value = 1.117 in the lahar deposits. The main driving factor of mass movement was the increasing soil mass due to the effect of rainfall.