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PENGARUH TEKTONIK PADA LEMBAH SUNGAI CILIWUNG DENGAN PENGUKURAN GPS- RTK BERDASARKAN NILAI VALLEY-FLOOR RATIO (Vf) Witjahjati, Retno; Sukiyah, Emi; Winantris, .; Arya, Pulung P; Nugroho, Bani
Bulletin of Scientific Contribution Vol 16, No 2 (2018): Bulletin of Scientific Contribution GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/bsc.v16i2.18171

Abstract

Most of Jakarta's Special Capital Region (DKI) has relatively flat topography covered by alluvial deposit. Alluvial deposit derives from rock deformation of volcanic activity in the south, and also coastal deposits at the north part. The upstream rivers located in hilly, mountainous terrain, as well as through sloping hills to the lower plains downstream. The relatively rapid flow velocity in the upstream forms the parallel pattern and the downstream are slowly forming a sub dendritic pattern until it empties into the Jakarta Bay. Ciliwung River is one of 13 rivers passing through DKI Jakarta.The morphology of DKI Jakarta area is formed by exogenous energy caused by highly intensive sedimentation and human activities. In addition, there is also endogenous energy to produce folds and fracture structures. The presence of endogenous power results from the convergence interaction between the Indian-Australian Ocean Plate and the Eurasian Plate.This research was conducted to find out the influence of endogenous power in the form of tectonic control on the pattern of landscape shape in DKI Jakarta. The manifestation of these endogenous influences can be seen in the morphological formation in the Ciliwung River. The method used is calculated of morphometry with a value of the VF - ratio (Valley Floor Ratio) from topographic measurement using GPS-RTK device (Global Position System - Real Times Kenematic). Measurements were made as many as 7 trajectories on the river banks in order to know the difference of elevation on the left and right side. Based on the calculation, the Vf value ranged from 1.65 to 3.47. Through these results, it can be concluded that the morphology of DKI Jakarta is controlled by tectonic process with medium category.
KUALITAS BATUGAMPING BERDASARKAN ANALISIS KLASIFIKASI GEOMEKANIK DI GOA SEROPAN, GUNUNG KIDUL, YOGYAKARTA Nugroho, Bani; Pranantya, Pulung Arya; Utomo, Edi Prasetyo
Bulletin of Scientific Contribution Vol 14, No 1 (2016): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1136.284 KB) | DOI: 10.24198/bsc.v14i1.9792

Abstract

Seropan cave is one of the caves in Semanu sub District, located in the karst region, Gunung Kidul, Yogyakarta. Based on reserach of Karlsruhe Institut of Teknology (KIT) German, is known underground river in the cave is very potential to be developed. Underground dams and micro hydro installations built to pump water upwards the river. These are used as raw water for daily needs and irrigation in the surface.  For this purpose it is necessary to study the stability of the rock mass in the cave Seropan. The stability of a tunnel or cave is heavily influenced by geological and non-geological factors. The most dominant geological factors in general are geological structures, can be muscular or fault, the type of rock and rock mass quality.The rocks at the cave Seropan in general are limestones. Based on rock mass classification of Rock Mass Rating (Bieniawski, 1989) otherwise known as the geomechanics classification, these rocks are included in class III and class IV. These rocks include moderate to bad quality. Until now the cave conditions remained relatively stable and secure. This is due to the naturally formed cave. The process of distribution of stresses around the cave coincided with the formation of caves and takes place in a relatively long time. However, in some parts of the cave should be because the effect of fractures can lead to collapse of the roof of the cave.