Numerical calculation methods for landslide hazard assessment are typically applied on small areas. However, based on simple geotechnical models, the application is also useful for large areas. The utilization of grid-based geometrical and geological data in combination with geotechnical parameters allows calculating of well-known safety factors for slope failure in rock and soil. Furthermore, the effect of water availability on slope stability can also be taken into account and is useful to estimate the effect of long-term precipitation events on slope stability. The calculated safety factors can be represented on a map by means of geoinformation systems (GIS). This paper gives an overview of the applied calculation methods as well as GIS-supported visualization of the calculation results.
The assessment of landslide hazard is an important topic in earth sciences for many decades. Due to urbanization on sloping areas and an intensification of heavy precipitation events, a higher occurrence of slope instability and landsliding is reported.
A significant body of qualitative and quantitative methods for the assessment of landslide hazard is available (Aleotti & Chowdhury 1999). The major disadvantage when using qualitative methods is the problem of subjectivity and makes it difficult to compare landslide hazard maps by different experts. The use of quantitative methods, like the application of geotechnical models, based on widely used mathematical methods and is quite comprehensible. The index of stability is the well-known safety factor. The calculation can be fully automated and enables a quick slope stability assessment for large areas. By varying the input parameters, it is easy to calculate a range of possible safety factors. Such methods are typically applied only on small areas because they require many geometrical and geotechnical parameters. However, it is possible and in our opinion useful, to make an estimation of landslide hazard for large areas based on simple geotechnical models.
