GIS-Based Landslide Susceptibility Analyses: Case Studies at Different Scales

Abstract

Landslide hazards occur throughout the world. There were 18,000 deaths worldwide due to landslides between 1998 and 2017 (World Health Origination, n.d.). Furthermore, landslides are often triggered by other newsworthy hazards, such as earthquakes and hurricanes. As a result, the economic losses due to landslide hazards are generally more significant than those recognized. With the advancement of technology in geographic information systems (GIS), landslide hazards can be analyzed on different scales in a time-efficient and cost-effective fashion. However, methods have to be selected prudently relative to the study’s scale to take full advantage of the GIS. This paper focuses on landslide susceptibility analysis at different scales by using GIS-based methods. A typical GIS-based landslide susceptibility analysis includes (1) landslide inventory, (2) spatial data acquisition, (3) landslide susceptibility map generation, and (4) result accuracy assessment. We intend to demonstrate different landslide inventory techniques, data collection, map generation, and accuracy assessment through three case studies. The scales of these studies range from site-specific (up to 10s km2) to local (up to 100s km2) and regional (up to 1,000s km2). GIS-based landslide susceptibility studies can produce continuous landslide zonation maps and are typically conducted before the landslide risk analysis and mitigation design. The results of the landslide susceptibility studies can be used for dispatching limited resources to the areas in need of detailed research and mitigation, which is beyond the scope of this paper. The scale of the study area and data availability dictate the selection of methods in the case studies. The availability of time and budget also constrains the choice of methods for a project. For example, field mapping was used for landslide inventory for the site-specific study, while the interpretation of aerial photos and satellite images was used for the inventory of local and regional studies. Infinite slope and Bishop’s simplified method of slices were used to calculate the factor of safety in the site-specific studies. In contrast, empirical methods and the analytical hierarchy process (AHP) method were used for local and regional studies. The presented methods are applied in three case studies on GIS platforms. The suggested methods are not intended to be absolute and unchangeable. Instead, they are intended to provide insight to practitioners, researchers, and decision makers.