ABSTRACT:
We constructed a landslide susceptibility map of a specific dam site in Korea using GIS technique. Pack’s (1995) Stability INdex MAPping (SINMAP) technique, a stability index approach to terrain stability hazard mapping based upon the infinite slope stability model, is applied to construct a stability index map. Strength parameters such as cohesion (C) and internal friction angle (F) of various types of cover soils were analyzed from the laboratory and in-situ testing. Hydro-geological parameters to determine the wetness index were also calculated from simple laboratory and field tests. Statistical analysis was performed to improve the reliability of the field data. The result shows that the main triggering factors of landslides are geomorphologic and geological conditions (i.e. lithology and geological structures). Detailed field survey was carried out to evaluate the accuracy of the result. Many landslide events were observed in the SINMAP predicted unstable zone.
1 INTRODUCTION
SINMAP is an objective terrain stability mapping method (Pack 1995) that takes advantage of GIS (Geographic Information System) technology to quantify geographic attributes about slope instability and landslide hazard, and to express patterns of instability at the scale of the DEM (Digital Elevation Model). The method is applied to shallow transitional debris landslides controlled by subsurface groundwater. In order to calibrate input parameters during the modeling process and examine the accuracy of the modeling result, detailed field survey is carried out. Through the direct verification, the reliability of the SINMAP approach would be validated.
2 THEORETICAL BACKGROUND OF SINMAP APPROACH
The method is based upon the infinite slope stability model (Fig. 1) with the steady state hydraulic model (Hammond et al. 1992, Montgomery & Dietrich 1994) that balances the destabilizing (gravity) and restoring (friction, cohesion) components.
