Interpretasi Citra untuk Analisis Kapasitas Sungai Unda sebagai Tampungan Lahar Dingin Erupsi Gunung Agung Bali

Interpretasi Citra untuk Analisis Kapasitas Sungai Unda sebagai Tampungan Lahar Dingin Erupsi Gunung Agung Bali NI KADEK DIAN ASRI LESTARI NI MADE TRIGUNASIH*) I NYOMAN DIBIA R. SUYARTO Program Studi Agroekoteknologi Fakultas Pertanian Universitas Udayana Jl. PB. Sudirman Denpasar Bali 80232 Bali *)Email: trigunasih@unud.ac.id ABSTRACT Imagery Interpretation for Analysis of Unda River Capacity to Retain Lahars Flow of Agung Volcano Eruption This study aims to determine the flow capacity of Unda River to retain lahars flow of Agung Volcano eruption using a descriptive exploratory method, the data through field surveys and analysis of satellite imagery. Sampling was determined based on the gradient and river's meander to produce 14 samples and 13 segments in the river flow. The cross section of the river is measured at each sample point with the mean section method, then estimating the volume of the river by multiplying the area between the two sections with the distance of the sample point. The lahar flood hazard assessment uses the Laharz application with the lahars scenario 1 million m3; 5 million m3; and 10 million m3. The results of the study showed that the capacity volume of the Unda River was 26.336.548,79 m3. Estimated area affected by scenario 1 million m3 covering 162,60 Ha; scenario 5 million m3 covering 399,19 Ha; and the scenario of 10 million m3 covering 533,77 Ha. The affected area reached 27 villages in the Karangasem Regency region and 20 villages in the Klungkung Regency area. The highest affected area for scenario of 1 million m3 is Muncan Village about 32,70 Ha; scenario 5 million m3 in Selat Village, Klungkung is 68,43 Ha; and the scenario of 10 million m3 in Tangkas Village about 266,01 Ha. The type of land use that affected is rice field land about 458,08 Ha; moor / mixed garden at 71,33 Ha; settlements is 147,72 Ha; and shrubs about 3,98 Ha. Keywords: meanders, cross sections, river basins, lahar scenarios