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LANDSLIDE INVESTIGATION AND STABILITY ANALYSIS FOR DESIGNING MONITORING AND WARNING SYSTEM

BUI, TUAN ANH, Prof. Teuku Faisal Fathani, ST., MT., Ph.D.; Dr. Wahyu Wilopo, ST., M.Eng.

2019 | Tesis | MAGISTER TEKNIK PENGELOLAAN BENCANA ALAM

Tanah longsor adalah bencana alam yang paling sering terjadi di Yogyakarta, Indonesia. Pada pertengahan Maret 2018, beberapa retakan muncul di utara bukit di Desa Pendoworejo, Kecamatan Girimulyo, Kabupaten Kulon Progo, Provinsi Daerah Istimewa Yogyakarta. Akibatnya, gerakan tanah longsor di daerah ini mengancam penduduk dan membuat mereka dievakuasi karena ketakutan mereka terhadap potensi bencana tanah longsor. Untuk mengurangi risiko tersebut, beberapa tindakan pencegahan stabilitas dilakukan. Analisis stabilitas dalam hal ini difokuskan pada hubungan faktor keamanan, kecepatan dan fluktuasi muka air tanah akibat curah hujan. Setelah itu, sistem monitoring dan peringatan dini dirancang sebagai salah satu bagian dari upaya mitigasi. Berdasarkan investigasi awal pada April 2018, tidak ada bukti gerakan massa di bagian barat dan selatan bukit. Di sisi lain, daerah bagian utara diperkirakan memiliki risiko longsor karena banyakditemukan situs yang retak. Berdasarkan hasil analisis tersebut, fluktuasi muka air tanah berubah secara substansial baik sebelum maupun sesudah hujan lebat terjadi. Selain itu, faktor keamanan turun sekitar 20% secara signifikan dengan peningkatan kecepatan gerakan tanah longsor. Bahkan, risiko tanah longsor meningkat di setiap musim hujan. Sehingga, risikonya dapat lebih berbahaya di waktu yang akan datang.

Landslide is the most frequent natural disaster in Yogyakarta, Indonesia. In the mid-March 2018, a few cracks appeared in the north of the hill in the Pendoworejo Village, Girimulyo Sub-District, Kulon Progo Regency, Yogyakarta Special Province. Nevertheless, the landslide movement of this area still threatens the residents and makes them evacuated due to their fear upon potential landslide disaster. In order to reduce the risk, some stability actions were conducted. The stability analysis in this case focused on the relationship of the safety factor, the velocity and the fluctuation of groundwater level due to the rainfall density. After that, a monitoring and warning system is designed as a mitigation work. Based on the preliminary investigation on April 2018, there was no evidence of mass movement on the west and south part of the hill. On the other hand, the north part area was estimated to have risk due to occurring many sites of crack. Based on the result of analysis, the fluctuation of the groundwater level rose or droped substantially before and after heavy rainfall. Also, the safety factor dropped about 20% with increase of landslide movement velocity by many time. In fact, the landslide risk increase in every rainy season. So that, the risk could be more dangerous in the future.

Kata Kunci : Slope stability analysis, GIS, Field investigation, Landslide mitigation, Early warning devices.

  1. S2-2019-421331-abstract.pdf  
  2. S2-2019-421331-bibliography.pdf  
  3. S2-2019-421331-tableofcontent.pdf  
  4. S2-2019-421331-title.pdf