Engineering geological analysis for landslide susceptibility mapping in Gia Nghia Area, Dak Nong Province Vietnam

TIN, Nguyen Huy, Prof. Ir. Dwikoraita Karnawati, M.Sc., Ph.D

2009 | Tesis | S2 Teknik Geologi

Wilayah Gia Nghia, berlokasi di provinsi Dak Nong, Vietnam, jauh dari kota Ho Chi Minh sekitar 225 km, kota Buon Ma Thuot sekitar 120km dan kota terebut mempunyai arti penting dari provinsi Dak Nong. Kebanyakan belajar wilayah tertutup lapisan basal sepanjang Neogene ke Quatemari (β/N2-Q1tt: Fentuk Tuc Trung); kemanapaun mengarah endapan purba permulaan- pertengahan (J2ln: Fentuk La Nga), di barat (W) dan tengara (SE), diantara mereka, kerusakan lapisan basal adalah sangat rentan untuk terjadinya longsor di wilayah itu. Sebagai bukti, kebanyakan penyaluran longsor yang sudah terjadinya di kerusakan lapisan basal. Penelitian ditunjukan untuk mengembangkan pemetaan kerentanan longsor pada skala 1/25,000 dengan alat-alat system informasi geografi (GIS) yang akan mempertimbangkan kerentanan wilayah longosr dengan derajat bermacam-macam kerentanan. Koleksi data, pengamatan tempat dan kerjaan lainnya dibentuk untuk mengidentifikasi kondisi geomorphology dan geologi penyumbang terhadap kejadian lognsor di wilayah 6 tema data lapisan dihasilkan termasuk: kecondongan miring, ketinggian, jarak dungai, jarak kawah vulkanik, tipe-tipe itiologi dan kegunaan tanah dan yang disiapkan untuk menganalisa. Perlunya pembatsan data, kebanyakan data proses dilakukan dalam kerangka GIS dengan metode gabungan peta kualitas yang berdasar pada pengalaman,pengetahuan dan tinjauan literature dan sebagainya. Terakhir, hasil peta kerentanan longsor menggambarkan wilayah ke dalam perbedaan zona 5 tingkat kerentanan relative: sangat rendah, rendah, sedang, tinggi dan sangat tinggi, hasil diverifikasi dengan membandingkan penyaluran longsor pada waktu dulu. Ada 11/6 poin penyaluran longsor pada waktu dulu ada dalam tingkat kerentanan tinggi dan sangat tinggi

Gia Nghia area, located in Dak Nong province, Vietnam, is far from Ho Chi Minh city about 225km, Buon Ma Thuot city about 120km and it has a good significant of Dak Nong province. Mostly of the study area covered by basalt layer during Neogene to Quaternary (β/N2 – Q1tt: Tuc Trung Formation); somewhere exposed Early – Middle Jurassic sediments (J2ln: La Nga Formation) in West (W) and Southeast (SE), among them, weathering crust of basalt is very susceptible to landslide occurrence in the area. For evidences, most of landslide distribution in the past already occurred in weathering crust of basalt. The research is aimed to develop landslide susceptibility mapping at 1/25,000-scale by Geographic Information System (GIS) tools which will consider the susceptible landslide area with the various degree of susceptible. Data collection, site observations and other works were performed to identify the conditions of geomorphology and geology, contributing to landslide occurrences in the area. Six of thematic data layers were generated include: slope inclination, elevation, distance to rivers, distance to volcanic craters, lithology types and landuse and were prepared to analyze. Due to the limitation of data, most of data processing is done in GIS framework by a qualitative map combination method which based on the field experience, field knowledge, and literature review and so on. Final, the result of landslide susceptibility map delineates the area into different zones of five relative susceptibility classes: very low, low, medium, high and very high susceptibility. The result was verified by comparing to landslide distribution in the past. There are 11/16 points of landslide distribution in the past were in high and very high susceptible classes.

Kata Kunci : Kerentanan longsor,System informasi geografi,Factor keamanan,Gabungan peta kualitas, Landslide susceptibility, Geographic Information System, factor of safety, qualitative map combination