Influence of Rainfall Intensity to Lahar Flood Velocity and Heigth Based on Simlar 2.1 Modelling

Rokhmat Hidayat; Akhyar Musthofa; Pedri Bahri

doi:10.32679/jth.v8i2.482

Influence of Rainfall Intensity to Lahar Flood Velocity and Heigth Based on Simlar 2.1 Modelling

Rokhmat Hidayat, Akhyar Musthofa, Pedri Bahri

Abstract

Large amount of active volcanoes distribution makes Indonesia a country vulnerable to lahar flow. Although lahar flow is categorized under volcanic eruption secondary disaster, it has large impacts in environmental, social, economic, infrastructure and casualties. For example, the incident of lahar flow disaster triggered by high rainfall was occurred in Putih River Magelang, on 24th January 201 . This study discusses the effect of rainfall intensity on lahar flow velocity and height. This study was carried out using a numerical model, SIMLAR 2.1, in Putih River, located on western slopes of Merapi Volcano, Magelang, Central Java. Modeling was performed by using several rain intensity scenarios, i.e. 60mm/hour, 70mm/hour, 80mm/hour, 90mm/hour and 100mm/hour. The velocity of lahar flow simulated by the model was validated using lahar flow velocity data from field measurement. The results showed that rainfall intensity has linear correlation with lahar flow velocity and height. Higher rainfall intensity results in higher lahar flow velocity and height. In addition, the modelling result also showed that the largest lahar flow velocity (2,88m/s) occurred when the rainfall was 100mm/hour and has a deviation of 17.71% compared to previous observations. In average, lahar height in the River increases around 24.31% when the rainfall increases 10 mm/hour.

Keywords

Volcanoes; lahar flow; SIMLAR 2.1; flow velocity; lahar height

Full Text:

PDF (Bahasa Indonesia)

References

Bates R. L., dan Jakcson J. A., 1987, Glossary of Geology, American Geology Institute, Virginia, Amerika

Badan Geologi, 2010, Penurunan status aktivitas Gunung Merapi dari Awas ke Siaga, diakses dari web, http://www.merapi.bgl.esdm.go.id/pdf/2010/1 2/EvaluasiAWAS_SIAGA_Merapi_3Des2010_527 9a6.pdf , pada 22 Januari 1918 BNPB., 2011. Panduan Perencanaan Kontinjensi Menghadapi Bencana, Edisi-2.

Daryono, 2011, Ancaman Banjir Lahar Merapi. dalam http://data.bmkg.go.id/share/ Dokumen/artikelancaman_banjir-lahar-merapi-daryono-bmkg2011.pdf diakses pada tanggal 22 Januari 2018

Hidayat F., Rudiarto, I., 2013. Pemodelan Resiko Banjir Lahar Hujan Pada Alur Kali Putih Kabupaten Magelang, Jurnal Teknik PWK Volume 2 Nomor 4, Universitas Dipenogoro.

Giyarsih S., R., Gamayanti, P. 2014. Dampak Banjir Lahar Terhadap Aspek Sosial: Studi Kasus Banjir Lahar Pasca Erupsi Merapi Gunung Merapi 2010 di Kecamatan Cangkirngan. Yogyakarta: Gadjah Mada University Press.

Ikhsan J., 2014, Studi Numerik Perubahan Elevasi dan Tipe Gradasi Material Dasar Sungai, Simposium Nasional Teknologi Terapan 2 (SNTT 2): S-7 - S-15.

Kumalawati, R., Rijanta, Sartohadi, J., & Pradiptyo, R. 2010. Evaluation of Settlement Damage Due To Lahar Flood in Kali Putih. UGM, Yogyakarta.

Kusumosubroto, H., 2013. Aliran Debris dan Aliran Lahar, Pembentukan, Pengaliran, Pengendapan dan Pengendaliannya, halaman 221-295, Graha Ilmu, Yogyakarta.

Markowska, J., 2012. Aplication of HEC-RAS Model For Estimating Changes In Watercourse Geometry During Floods., Studia Geotechnica et Mechanica, Vol. XXXIV, No. 2: 63-72.

Mulyaningsih, S., 2015. Vulkanologi, Yogyakarta: Penerbit Ombak.

Musthofa, A., 2015. Simulasi Banjir Bandang untuk Sistem Peringatan Dini dan Peta Bahaya. Tesis, Yogyakarta: UGM.

Sanghyun K., Taebok S., Hyunjun K., Kwangjun J., Sungwook K., Khilha L, Sung-Hyo Y. 2013. Prediction of Lahar Inundation Area for Volcanic Eruption of Baegdusan using LAHARZ. IAVCEI Scientific Assembly - July 20 - 24 Kagoshima, Japan Forecasting Volcanic Activity - Reading and translating the messages of nature for society: 972.

Ramadhan S., 2016. Pemanfaatan Aplikasi LAHARZ Untuk Model Lahar di Sungai Gendol Menggunakan Data LIDAR, Tugas Akhir. Yogyakarta: Universitas Gadjah Mada.

Harto S., B., 1993. Hidrologi: Teori, Masalah, Penyelesaian. Nafiri Offset, Yogyakarta.

Shinta D., 2015, Mitigasi Bencana Lahar Hujan Gunungapi Merapi Berbasis Sistem Informasi Geografis dan Penginderaan Jauh di Sub DAS Kali Putih Kabupaten Magelang. thesis, Universitas Muhammadiyah Surakarta

Sulistiyani, Nandaka IGM, Atin L.S., Sulistio A., Nurudin, dan Rozin M., 2015 Aplikasi Metode Korelasi Silang untuk Perhitungan Kecepatan Aliran Lahar di Kali Putih, Kali Boyong, dan Kali Senowo. Yogyakarta: BPPTKG.

Takahashi, T., 2007. Debris FLow: Mechanic, Prediction, and Countermeasures. Leiden: Taylor & Francis. Hardjosuwarno S.,

Raharjo A. P., Ikhsan J., Rosyadi I., 2012, Panduan Pengoperasian Program Simulasi 2D Banjir Lahar (SIMLAR), Balai Litbang Sabo, Kementerian PU, Yogyakarta.

DOI: https://doi.org/10.32679/jth.v8i2.482