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Journal : Eksplorium : Buletin Pusat Pengembangan Bahan Galian Nuklir

UPSTREAM HYDRAULIC INTERCONNECTION STUDY OF GUNUNGKIDUL KARST AREA UNDERGROUND RIVERS Sidauruk, Paston; Satrio; Pujiindiyati, Evarista Ristin; Aliyanta, Barokah
EKSPLORIUM Vol. 38 No. 2 (2017): NOVEMBER 2017
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2017.38.2.3715

Abstract

Hydraulic interconnection of Jomblangan (Petung) cave with other caves and water discharges in Gunungkidul karst area has been investigated using tracer techniques and verified by stable isotopes and hydrochemical data interpretation. Many studies have been conducted to study the interconnections of underground rivers around Gunungkidul Karst area, most of them, however, focused on the interconnection of underground rivers around Bribin and Seropan caves. This is because of the development of micro hydro turbines to lift the water from underground river were still focused around Bribin and Seropan caves. Petung, located to the north of Bribin and Seropan caves, was believed to be one of the cave at the upstream of Bribin and Seropan caves, however, there is no evidence yet of the hydraulic interconnection between Petung cave with either Bribin or Seropan caves. The results of tracer technique at the current study, showed that there was no hydraulic interconnection between Petung cave with either Bribin and Seropan caves. On the other hand, the study showed an indication of a direct flow from Petung cave to Sriti and Beton springs. The travel times from Petung to Sriti and Beton springs were found to be around 2 and 10 hours, respectively. This finding is also in agreement with the results of chemical and stable isotopes analysis.
Konsentrasi Radon-222 dalam Gas Tanah untuk Deteksi Distribusi Permeabilitas di Daerah Panas Bumi Tampomas, Jawa Barat Prasetio, Rasi; Laksminingpuri, Neneng; Pujiindiyati, Evarista Ristin
EKSPLORIUM Vol. 41 No. 1 (2020): MEI 2020
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2020.41.1.5642

Abstract

Upflow zone in the geothermal system is a zone with high permeability that serves as a path for geothermal fluid to ascend to the surface, which usually marked with fumarole at the surface. Mount Tampomas, West Java, is a potential geothermal site with some thermal manifestation in the form of hot springs, but no fumarole or steam vent exists. The up-flow or the permeable zone is difficult to identify. 222Rn isotope is a radiogenic isotope that its concentration in soil gas can infer primary permeability as well as secondary permeability (structure). Series of 222Rn measurement in soil gas has been performed from 56 sampling positions around Mount Tampomas to evaluate 222Rn anomaly by a statistical method and its relation with high permeability area, geological structure, and geothermal manifestation. The measurement and statistical evaluation results show that 222Rn concentration clustered into low (background), high, and anomaly concentration. The background values in 16 places are below 825 Bq/m3, while a high level in 32 areas between 825–7688 Bq/m3 and anomaly in 8 places above 7688 Bq/m3. Most of the locations with high and anomaly 222Rn concentrations did not locate near a structure lineament. All measurements near hot springs have a high 222Rn and anomaly. Ciseupan hot spring is an exception which may indicate that the hot spring is discharged laterally (outflow). Furthermore, there is no indication of a correlation between 222Rn with the elevation of the measurement location. The process of 222Rn transfer from the reservoir to the surface is considered by the geothermal reservoir's gas carrier mechanism through permeable zones.
Aplikasi Isotop Alam (18O, 2H dan 14C) untuk Studi Dinamika Air Tanah dan Hubungannya dengan Air Sungai di Daerah Bandung Pujiindiyati, Evarista Ristin; Satrio, Satrio
EKSPLORIUM Vol. 34 No. 2 (2013): NOVEMBER 2013
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2013.34.2.2803

Abstract

Water table in the center of Bandung basin has been decreased around 1-2 m/year since 1990 whereas in the slope has been decreased at higher level of 15 m. Water level decreasing are going to increase continuously because of increasing number of deep wells (>40 m). In 1970, there were 96 deep wells which have been registered, but now number of deep wells is estimated of more than 4700. Therefore, a study of interrelationship between groundwater and surface water, and determination of recharge area for Bandung basin are crucial research to be conducted. Stable isotopes in nature such as 2H and 18O, and radioactive isotope of 14C can give important information about groundwater dynamic pattern. In this research, 24 deep groundwater samples, 28 shallow groundwater and river water samples (Citarum, Cikapundung, Cikeruh and Citarik rivers) and shallow groundwater along the rivers were collected. Results from plotting d18O and d2H showed that most of shallow groundwater did not relate to river water except three locations, they are Loteng Sumbersari and Bojong Mas groundwater near to Citarum river, and groundwater near to Cikapundung river. Isotope 14C analysis indicated that deep groundwater of Bandung basin did not show relationship either by shallow groundwater or river water. Its iso-age line contour determined that dynamic pattern of deep groundwater in Bandung basin comes from northern and southern hills to direction of north-west area such that both areas are suggested as conservation zone. Rate of deep groundwater movement predicted from iso-age contour is around 0.25 to 3 m/year.