Landslides qualitative hazard and risk assessment method and its reliability

Landslide hazard and risk assessment methods can be broadly characterised as site specific or area specific. Site specific assessments may be qualitative (denoted Type I) or quantitative—based on detailed investigation and data (Type III). Area specific assessments are denoted as Type II.This paper describes the University of Wollongong Type I method which analyses hazard and risk assessment for four different conditions: natural slopes, embankments and side fills, rock slopes and cuttings and soil cuttings. Field sheets have been developed for each type of slope to enable scoring of the factors contributing to hazard and to consequence and therefore to risk. These have been tested at 23 sites in New South Wales, Australia, by two independent professionals to establish consistency levels. Some Type III assessments have been made against which the Type I assessments were compared. In the three areas reported, the comparisons indicate that the qualitative approach is conservative.