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Journal : JLBG (Jurnal Lingkungan dan Bencana Geologi) (Journal of Environment and Geological Hazards)

Kontrol Morfotektonik Terhadap Gerakan Tanah di Daerah Malalak, Sumatra Barat Donny R. Wahyudi; Sumaryono Sumaryono; Emi Sukiyah; Dicky Muslim; Arif R. Darana
Jurnal Lingkungan dan Bencana Geologi Vol 6, No 3 (2015)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1916.137 KB) | DOI: 10.34126/jlbg.v6i3.86

Abstract

ABSTRAKPenelitian ini bertujuan (1) untuk mengidentifikasi tingkat aktivitas tektonik DAS (Daerah Aliran Sungai) Manggur Gadang berdasarkan analisis morfometri yang berupa rasio perbandingan lebar dasar lembah dengan tinggi lembah (Vfw), indeks gradien sungai (SL), asimetri sungai (AF), sinusitas muka gunung (Smf) dan kerapatan sungai (dd).(2) untuk mengetahui hubungan kekar dengan segmen sungai, dan (3) untuk mengetahui hubungan longsor yang disebabkan oleh peristiwa gempa bumi dengan aktivitas tektonik. Aspek-aspek geomorfik seperti dimensi dan bentuk DAS dianalisis menggunakan morfometri untuk mengidentifikasi keaktifan tektonik wilayah penelitian. Azimuth segmen sungai dan struktur geologi berupa data kekar dan kelurusan azimuth mahkota longsor yang terjadi di lokasi penelitian dikumpulkan sebagai sampel yang selanjutnya dilakukan uji statistik untuk mengetahui hubungan antarvariabel tersebut.Hasil uji statistik yang dilakukan pada variabel diatas menunjukkan adanya hubungan antara segmen sungai dengan kekar dan azimuth mahkota longsor yang terjadi. Analisis morfometri juga menunjukkan adanya aktivitas tektonik dengan tingkat yang paling tinggi berada pada DAS Manggur Kecil, sedang pada DAS Manggur Gadang, dan rendah pada DAS Naras. Berdasarkan hasil penelitian diatas diketahui bahwa wilayah penelitian memiliki tingkat aktivitas tektonik aktif.Kata kunci: aktivitas tektonik, longsor, morfometriABSTRACTThis study aims(1)toidentify the level of tectonic activity based on morphometry analysis; ratio of valley floor width to valley height ( Vfw ), stream gradient index ( SL ), asymmetry factors ( AF ), sinuosity of mountain front ( Smf ), drainage density ( Dd). (2) to know the relation between rock joint with river segments, and (3)to determine the relation of landslides caused by earthquakes with tectonic activity. Geomorphic aspects such as the dimensions and shape of the watershed were analyzed by using morphometry to identify the tectonic activity level of the studied area. The river segment azimuths and geological structures such as joint and azimuth of crown landslide lineament that occurred at the studied site were collected as a sample of whichthen statistical tests were performedto determine the relation between these variables.The results of the statistical test that were performed on the variables above show that there is a relation between the river segment with joint and landslide crown azimuth that occurred. Morphometric analysis also shows the presence of tectonic activity with the highest levels on the watershed of ManggurKecil, medium on the watershed of Manggur Gadang, and low on the watershed of Naras. Based on the results of study above it is known that the studied area has an active tectonic activity level.Keywords : tectonic activity, landslide,morphometry
Simulasi aliran bahan rombakan di Gunung Bawakaraeng, Sulawesi Selatan Sumaryono Sumaryono; Yunara Dasa Triyana
Jurnal Lingkungan dan Bencana Geologi Vol 2, No 3 (2011)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2320.637 KB) | DOI: 10.34126/jlbg.v2i3.31

Abstract

SARIAliran bahan rombakan (debris flow) adalah fenomena di mana percampuran air, lumpur, dan kerikil mengalir dengan kecepatan tinggi. Karena aliran debris flow memiliki viskositas dan kecepatan yang tinggi, maka bersifat sangat merusak karena mengangkut material yang dilalui di sepanjang sungai sehingga volume dan energinya semakin meningkat dan dapat merusak rumah, jembatan, dan infrastruktur, dan mengakibatkan korban jiwa. Simulasi numerik penting untuk memastikan bahwa bangunan penahan bekerja secara efisien sebelum dilaksanakan pekerjaan konstruksi seperti dam sabo. Makalah ini menyajikan simulasi numerik dua dimensi dengan menggunakan Kanako, GUI dilengkapi simulator aliran debris, yang memungkinkan visualisasi dengan baik dan mudah. Kanako (ver. 2.0) diterapkan pada studi kasus di Gunung Bawakaraeng, Sulawesi Selatan, Indonesia. Simulasi diuji dalam berbagai kondisi termasuk kasus tanpa dam sabo dan dengan dam sabo seri. Hasil simulasi menunjukkan jika tidak ada dam sabo di Kampung Paragang, Lengkese, dan Raulo berpotensi terlanda debris flow. Over flow dan debris flow dapat ditanggulangi dengan 4 seri dam sabo tipe celah.Kata kunci: aliran bahan rombakan, pencegahan efektif, simulasi numerik, dam saboABSTRACTDebris flow is a phenomenon in which a mixture of large quantities of water, mud, and gravel flows down stream in high speed. Due to its high density and velocity, debris flow is very devastating, it carries along every things on its path that increases its volume and energy, hence it can destroy settlements, bridges, infrastructures as well as loss of lives. Numerical simulation is important to ensure that retaining construction works efficiently before sabo dam is built. This paper presents two-dimensional numerical simulations of a debris flow using Kanako, a user-friendly GUI-equipped with debris flow simulator that allows good visualization and easy explanation. Kanako (Ver. 2.0) was applied as to a case study at Bawakaraeng Mountain, south Sulawesi, Indonesia. Simulations were tested in various conditions with and without sabo dams including sabo dam series. The simulation results showed that without sabo dams, Paragang, Lengkese and Raulo are potentially affected by debris flow. Slit sabo dam of 4 series type is the most appropriate construction from being affected by over flow and debris flow.Keywords: debris flow, effective countermeasure, numerical simulation, sabo dam