Landslide-Susceptibility Mapping in the Amahata River Basin, Japan

Abstract

Abstract This study is concerned with (1) defining the terrain parameters and attributes that are important to landsliding in the Amahata River basin near Tokyo, Japan and (2) mapping landslide susceptibility from these characteristics. After aerial photographic interpretation and field surveys, ten terrain parameters, which were thought to be important to landsliding, were measured at each landslide and at the intersections of a 250-meter grid. Failure rate analysis and quantification scaling type II suggest that slope gradient, aspect, slope plan form, break of slope, elevation, and vegetation are the most critical site characteristics. Landslide-susceptibility mapping was then accomplished by combining the three most basic terrain parameters: slope gradient, aspect, and slope plan form. First, stable and unstable categories were separated; then each category was divided into two classes to give four susceptibility classes: high, moderate, low, and least. These classes represent a qualitative index of the likelihood of a landslide occurring during heavy rainfall.