A Review of the Uses of GIS Relating to Landslide Mapping

GIS and Landslide Susceptibility Mapping Regardless of criteria, landslides can be considered one of the most costly natural hazards. They do enormous damage to infrastructure, water and electricity networks and there exists the ever- present possibility to cause loss of life. Whilst not the focus of t his essay, it is worth noting that the causes of landslides are exceptionally complex and incorporate geological, geomorphologic and meteorological pro cesses (Sarkar and Kanungo, 2004). Unlike some hazard events l andslides are world-wide phenomena and as such the approaches to mapping them vary enormously. Mapping landslides is very useful in managing and mitigating the impacts of landslides (Anbalagan et al, 1993 and Kienholz, 1978). GIS is used extensively to map landslide events, it is possible to identify three main approaches to this. These broad categories tend to have differing focuses and work best at a specific scale or location. The first of these approaches is know n as heuristic mapping. Heuristics comes from the Greek , meaning to find or discover, in the context of GIS it refers to an experience or knowledge based methodology. Heuristic approaches can take two forms, either direct or indirect mapping. Direct mapping involves the production of a field map based on observations conducted by a professional. The study area is divided into polygons base d on g eological characteristics. These polygons can then be assessed by a specialist . The results of this analysis usually take the form of a series of qualitative statements e.g., highly susceptible to landslides, somewhat susceptible to landslides etcetera. These results are mapped using GIS to give the final output. The second form of heuristic mapping is known as indirect mapping. In this an expert assesses the likelihood of a landslide based on existing data. Of all methods studied this is the most subjective. The second method identified from literature is known as deterministic mapping. This method involves the use of detailed geological data and physical characteristics as well as hydrological data for the study area. This data is placed within a modelling e nvironment, commonly a dedicated piece of software, to calculate values based on slope s tability models (Vanackera et al, 2003). The most widely used slope model is known as the infinite slope model.

A Review of the Uses of GIS Relating to Landslide Mapping

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