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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.
Laju Sedimentasi di Dataran Banjir Sungai Ciujung Hulu Berdasarkan Profil Pb-210 Excess Aliyanta, Barokah; Suhartini, Nita
EKSPLORIUM Vol. 39 No. 1 (2018): MEI 2018
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2018.39.1.4165

Abstract

The rate of deposition of sediment on the floodplain area is one of the constituent component of the sediment budget in watersheds. Therefore, the sedimentation rate estimation has been made in two locations of the floodplains based on the age sediment obtained using Pb-210 excess technique. Sediment cores were taken in the Ciujung Hulu River floodplain every 10 cm depth intervals up to a depth of 120 cm. Sediment was obtained then dried, disaggregated, sifted, weighing 150–300 gr, placed into the special containers and tightly closed. After a month in a sealed condition, samples were measured using gamma spectrometer Multichannel analyzer (MCA) to find out the activity of Pb-210 total and Pb-210 supported. Based on the data of Pb-210 total and Pb-210 supported, there are three different ways to get Pb-210 excess profiles. Obtained Pb-210 excess data is used to calculate the age of the sediments on the basis of the method of constant rate of supply (CRS). Through the age of sediment layers, can be recognized the existence of transitional zone of sediment deposition rate at both locations. The rate of sedimentation ranged from 1.028 cm/year from the years 1968–1987, and rose to about 2.83 cm/year from the years 1987–2016 (28.95 years) at location 1. While in location 2, the rate of sedimentation ranged 0.676 cm/year from the years 1950–1993, and rose to about 3.231 cm/year from the years 1993–2016 (2 years).