Rhamadianto, Yogic Wahyu (2020) PEMETAAN POTENSI SINKHOLE DENGAN METODE VLF-EM (STUDI KASUS : PROYEK BENDUNGAN PENGENDALI AIR DAERAH BANYULANGSE, TUBAN). Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Kabupaten Tuban terletak di sisi Pantai Utara Jawa yang didominasi lingkungan pengendapan laut dangkal. Di beberapa area tertentu, terbentuk karst atau kompleks batukapur. Dalam waktu dekat, akan dibangun bendungan pengendali yang berlokasi di Banyulangse, Kecamatan Semanding. Bendungan ini memanfaatkan karst yang mengelilingi sungai sebagai penahan alami. Namun karst memiliki karakteristik yang mudah tererosi dan bereaksi oleh zat kimia terutama air sehingga kemungkinan besar terdapat sinkhole atau lubang bawah permukaan. Hal ini menjadi problematika ketika bendungan beroperasi nanti terutama saat debit air mencapai puncaknya.Untuk menangani hal tersebut, dilakukan pemetaan awal kondisi bawah permukaan area Banyulangse. Salah satu metode yang sesuai dengan alokasi medan adalah metode VLF-EM. Dengan sifatnya yang mobile dan rapid, metode VLF-EM dapat memetakan zona potensi sinkhole berdasarkan parameter konduktivitas yang dimiliki tanpa bantuan medium dan injeksi sumber energi. Lintasan akuisisi sebanyak 5 buah sepanjang 500-515 meter mengikuti aliran sungai dan 1 buah sepanjang 220 meter yang memotong sungai di ujung area pengukuran. Dari pengolahan data tipper, menjadi model kualitatif dan kuantitatif, diperoleh titik dugaan sinkhole berisi air dengan resistivitas 100-300 Ω.m dan berisi udara dengan resistivitas 550-650 Ω.m. Sinkhole berisi air terlihat pada lintasan 1 offset 100-200 meter dan kedalaman 45-50 meter, lintasan 4 pada offset 50-150 meter dan kedalaman 50-150 meter dan pada offset 440 meter dan kedalaman 45 meter. Sedangkan sinkhole berisi udara terlihat pada lintasan 5 pada offset 350 meter dan kedalaman 30-40 meter.
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Tuban Regency is located on the side of the North Coast of Java which discusses the shallow marine depositional environment. In certain areas, karst or limestones complexes are formed. In the near future, a dam will be built in Banyulangse, Semanding District. This dam utilizes karst which uses the river as a natural barrier. However, karst has characteristics that are easily eroded and reacted by chemicals that are needed so that most of them are sinkholes or subsurface holes. This is a serious problem of dam operation later especially when the water flow reaches its peak. For handling it, early survey should be conducted. One method that is suitable for field survey is VLF-EM method. By its mobility and rapid operation, the VLF-EM method can map the sinkhole zone based on the conductivity parameters without the aid of medium and injection of energy sources. Tracks has been obtained as many as 5 lines along 500-515 meters through the river and 1 lines 220 meters along which cut the river at the end of the acquisition track. From data tipper processing into qualitative and quantitative models, it is obtained that the alleged sinkhole contains water with interval of resistivity between 100-300 Ω.m and contains air with a resistivity of 550-650 Ω.m. Sinkhole containing water is seen at line 1 offset 100-200 meters and depth of 45-50 meters, line 4 at offset 50-150 meters and depth of 50-150 meters, and line 4 at offset 440 meters and depth of 45 meters. Whereas sinkhole filled with air is seen on line 5 at offset 350 meters and 30-40 meters depth.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Uncontrolled Keywords: | Bendungan,dam, karst, sinkhole, VLF-EM |
| Subjects: | G Geography. Anthropology. Recreation > GB Physical geography > GB600 Karst conservation. |
| Divisions: | Faculty of Civil Engineering and Planning > Geophysics Engineering > 33201-(S1) Undergraduate Thesis |
| Depositing User: | Yogic Wahyu Rhamadianto |
| Date Deposited: | 31 Aug 2020 02:05 |
| Last Modified: | 18 May 2023 14:54 |
| URI: | http://repository.its.ac.id/id/eprint/80877 |
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