Analysis of discharge and area of the debris flow based on geological structural and rainfall levels in the slopes of Mount Abang, Kintamani

Abstract

Geological structural and rainfall intensity causes the parameters of soil shear strength to decline, especially in the surface layer of soil in volcanic rocks that have not experienced weathering. Study of geological structures and rainfall intensity against the hazard of a landslide was destroyed on the slopes of Mount Abang in the Abang Batudinding Village. Soil investigations using the Geoelectric method and sampling at 6 boreholes. Geological analysis on interpretation of slope outcrops, average rainfall analysis of the Thiessen Polygon method and analysis of design flood discharge using the NHSU method. Analysis results show the morphology of the slopes of Mount Abang with a slope of more than 40% and lithology of weathered volcanic rocks consisting of volcanic breccias, and tuffs breccias in conditions rather mild to moderate weathering, if have average effective rainfall for 10-50 years at 238 mm/day. The results also show that the peak discharge of debris flow was 98.639 m3/sec with the volume of debris flow 50072.85 m3 and the width of the range was 49.5 m. This debris flow volume indicated that residents around the river with a range of 49.5 m are at risk of debris flow sediment with a thickness of 1-1.5 m.