45 research outputs found
Unconfined aquifer system of volcanics in the northern part of Bandung basinwest JavaIndonesia
Ketersediaan Air Embung untuk Memenuhi Kebutuhan Air di Kawasan Kampus Jatinangor Universitas Padjadjaran
Pengaruh dari pemanasan global salah satunya adalah perubahan pola cuaca. Perubahan tersebut menyebabkan debit sungai pada musim penghujan sangat tinggi sedangkan musim kemarau sangat rendah. Hal tersebut berdampak terhadap kebutuhan air baku dan konsumtif di sekitar kampus tidak terpenuhi sepanjang tahun. Penelitian ini bertujuan untuk mensimulasikan ketersediaan air dalam memenuhi kebutuhan air di sekitar kampus Jatinangor Universitas Padjadjaran. Metode yang digunakan adalah model debit F. J Mock dengan 80% nilai probabilitas debit andalan serta pola perhitungan 15 hari. Hasil menunjukan debit yang masuk ke dalam tampungan tinggi dengan debit terbesar pada fase kedua bulan Februari sebesar 54,68 liter/detik sehingga air yang dikeluarkan di outlet cukup tinggi. Namun sangat rendah ketika masuk pada bulan Juni. Tetapi dengan jumlah cadangan air yang ada dalam tampungan tetap bisa memenuhi kebutuhan air walaupun pada fase kedua bulan september selisih antara volume air didalam tampungan dengan air yang dipakai sangat tipis yaitu selisih 4.500 m3. Dengan demikian, dengan adanya embung ini air yang ditampung pada saat musim hujan bisa memenuhi kebutuhan air di sekitar kampus pada saat musim kemarau dan efektif pula dalam mengurangi resiko banjir di bagian hili
Temperature diffusion rate of weathered soil in a tropical area : A case study in surrounding LembangWest JavaIndonesia
Rock Discontinuity Patterns Development Along Crushed Zones Separated By Fault Movement
Multivariate analysis was applied to rock-discontinuities taken from areas, in which folded and faulted sedimentary rocks occur. The purpose of the analysis is to verify the responses of these discontinuities to faults, from which the really existing fault can be delineated and mechanism and intensity of the deformation on Tertiary sediments underlying Quaternary sediments can be revealed that explain the intensity of neotectonism as the deformation continued on the Quaternary deposits. The sample parameters consist of strike and dip of both bedding planes and left also right diagonal joint sets respectively. From every site of two study areas two sample groups were taken from two rock-blocks separated by a fault. The analyses on the six parameters of the samples exhibit the contribution of each parameter to the rejection of the hypotheses of no effect of fault can be examined, which lead into a conclusion about how far does the parameter indicate the existing fault. The conclusion in Study Area 1 is that both right and left joint sets are significantly affected by reverse fault, suggesting that these two joint sets in uplifted rock-block were still affected by the folding process after reverse movement of the fault. Then, in Study Area 2, means of strike of bedding planes and right joint set significantly differ as a result of left lateral-slip fault certainly moving along a fractured zone
PODRIJETLO I KVALITETA PODZEMNIH VODA BAZENA RAWADANAU, SERANG BANTEN, INDONEZIJA
Rawadanau is a tropical mountain swamp located in Serang, Banten, Indonesia. Rawadanau groundwater is the main source of supply for the Cilegon Banten industrial area. Knowing the origin and quality of the groundwater can help preserve existing resources. This paper aims to clarify the origin of Rawadanau groundwater with new evidence of stable isotopes (18O and 2H) and hydrochemical data. Field measurements included pH, temperature, EC, HCO3ˉ, while the analyses of cations, anions and stable isotopes were carried out in the laboratory. The existing water supplies include springs, excavated wells, and river water. Cluster hierarchy analysis based on water chemistry and stable isotopes can be grouped into two clusters, cluster K (K1 and K2) and cluster L. Data δ18O and δ2H springs in Rawadanau indicate that they are of meteoric origin and that there has been evaporation from several springs. Water comes from meteoric water with a stable isotope content of δ18O between -6.39 to -4.82 ‰ and δ2H between -41.35 to -31.30 ‰, which are controlled by two main mechanisms, namely rock dissolution and evaporation dominance. Aquifers are composed of volcanic rocks with a dominant composition of porphyritic andesite, basaltic andesite, and andesite. According to the multivariate statistical analyses results other than pH and SO4 2-, all parameters (cations and anions) showed a significant correlation. There are four hydrochemical facies of groundwater, namely Ca-HCO3, Ca-Mg-HCO3, Mg-Ca-HCO3, and Na-Cl.Rawadanau je područje tropske, planinske močvare u Serangu (Banten), Indonezija. Tamošnje podzemne vode glavni su izvor opskrbe industrijskoga područja Cilegon, Banten. Poznavanje njihova podrijetla i kvalitete može pomoći u očuvanju toga resursa. Cilj je ovoga rada objasniti podrijetlo tih voda s novim podatcima o stabilnim izotopima (18O i 2H) te hidrokemijskim podatcima. Terenska mjerenja uključila su pH, temperaturu, EC, HCO3ˉ, a analiza kationa, aniona i stabilnih izotopa napravljena je u laboratoriju. Postojeći izvori vode uključuju izvore, bušotine i rijeke. Načinjena je hijerarhijska analiza klastera na temelju kemije vode i stabilnih izotopa. Izdvojena su dva klastera: K (K1 i K2) te L. Podatci δ18O i δ2H iz izvora upućuju na meteorsko podrijetlo vode te na evaporaciju iz nekoliko njih. Meteorska voda sa sadržajem stabilnih izotopa δ18O između –6,39 i –4,82 ‰ te δ2H od –41,35 do –31,30 ‰ određena je dvama procesima, tj. otapanjem stijena i evaporacijom. Vodonosnici su sastavljeni od vulkanskih stijena pretežito od porfiritskoga i bazaltnoga andezita te andezita. Multivarijantna statistička analiza svih varijabli (osim pH i SO4 2-), tj. većine kationa i aniona, pokazala je znatnu korelaciju. Izdvojena su 4 hidrokemijska facijesa podzemne vode, redom: Ca-HCO3, Ca-Mg-HCO3, Mg-Ca-HCO3 i Na-Cl
Recharge Area on the Slopes of Volcano Based on Geological Setting, Content of Deuterium and Oxigen Isotopes of Groundwater Chemistry: Case Study on the Slopes of Salak Mountain, West Java
Indonesian is huge areas that have the highest precipitation in the world, therefore water deficit of groundwater is often happened at anywhere. This study was related to determination of recharge area with approached by combining geological setting, stable isotopes and chemictry content of groundwater. Case study was carried out at surrounding the Cicurug area, Sukabumi Prefecture, West Java Province. The area is the slopes of Salak Mountain that have elevation of 400 until 1,200 m mean sea level (msl). While, much groundwater supplies industry activities on elevation 450-500 m msl. Based on data and result analysis of the studies, the recharge areas was not around peak of mountain or near, but water infiltrated on elevation of 700-800 m msl for groundwater exploited by industries. Therefore, the accurate determination of recharge area becomes a key for the groundwater sustainability
Temporal variation in sandstone composition of Miocene Jatiluhur Formation in the Bogor Trough, West Java, Indonesia
Bogor Trough in the West Java are typified by turbidity deposits with the source are mostly characterized by volcanoclastic materials from the southern area. The Trough actually receipt the sediment from both volcanoclastic materials from the south and continental source from the north. But, the discussions of sediments in term of composition and temporal variation are rare to be reported, especially the sediments from the north. This manuscript intends to discuss the temporal variation in detrital compositional and depositional facies of the Neogene sediments that delivered from the north (i.e., Sundaland) into the Bogor Trough, which is represented by Miocene Jatiluhur Formation.
A total of 36 selected samples have been taken for identifying the minerals using a polarization microscope. Modal analysis of the Gazzi-Dickinson method was applied for this provenance study of sandstones samples, which are consisting largely of quartz and feldspar, then sedimentary rock and volcanic rock fragments, glaucony, mud chips and skeletal fragments.
Sundaland, a continental block highland area in the north, is interpreted to have been the provenance of sediments of the Jatiluhur Formation, which is also considered to be the source area for the Paleogene sediments. Granitic igneous rocks are interpreted as the source of dominance of monocrystalline quartz grains, or the product of long-distance transport of polycrystalline quartz from metamorphic rocks
But, however late Miocene samples (upper part of formation) represent that the size and amount of glauconite grains are increasing, and texturally mud supported. Volcanic rocks materials are also observed. The upper part of Jatiluhur Formation records the starvation of sediment discharge into the basin, which has been also promoted for development of carbonate reef Klapanunggal Formation in the self-margin setting, and suggesting that the basin have directly received or indirectly some contemporaneous volcanic provenances sediment from the southern area