Evaluation of Landslide Based Settlement Distribution in Manado City

Abstract

This research was conducted in Manado with the aim of identifying factors that could potentially cause landslide susceptibility, mapping the distribution of potential landslides, and evaluating the distribution of landslide-based settlements.The materials used in this study are daily rainfall maps, slope maps, geological / rock maps, fault maps, soil solum depth maps, land use maps, infrastructure maps and population density maps on a scale of 1: 75 000. The map used as research material sourced from documentation studies and interpretation of maps of the earth and satellite imagery. Likewise, other data needed to support this research was obtained through documentation studies and field measurements. Each variable is used to determine landslide scaling and weighting vulnerability. The sum of the multiplication scores and weights of each variable is categorized into five classes of landslide susceptibility levels, which are very light, mild, moderate heavy and very heavy. Settlement distribution analysis is carried out by overlapping between landslide maps and settlement maps using geographic information system (GIS) technology with ArcView GIS 3.3 software.The results of the study indicated that there were three factors that triggered landslide susceptibility in Manado that had a significant effect, namely geological / rock constituent factors, fault factors, and depth of soil solum. Other factors both physical and management factors have a weak influence on landslides because they are on slopes <25%. Most (91.57%) of the study area had very low to low landslide susceptibility. Therefore, the distribution of settlements in the study area is generally in areas that are safe from landslides. Only about 46.12 ha or around 1.17% of settlements in Manado are located in high landslide susceptibility areas. Settlements located in areas with high landslide susceptibility are spread across seven sub-districts, which are located in Bunaken, Tuminting, Mapanget, Sinkil, Pal Dua, Wanea and Malalayang Districts.