Geologic, topographic and climatic controls in landslide hazard assessment using GIS modeling: A case study of Souk Ahras region, NE Algeria

摘要

Landslides are the most common hazard in mountainous regions of northeast Algeria. In this study, landslide hazard zonation of Souk Ahras province was carried out using a Raster-based GIS and statistical processing. Landslide locations were defined from interpretation of aerial photographs and field surveys. Rotational, planar and complex landslides were identified. To reveal the controlling factors of landslides, a temporal distribution of 603 recognized landslides (1981-2011) is compared with the monthly precipitation variation, indicating a strong correlation between precipitation and landslide occurrence. The correlation between landslide and lithology, slope angle, and elevation shows the same results. Tabular data, maps and satellite images were collected, processed, and constructed into a spatial database in a GIS platform. The factors that influence landslide occurrence, such as slope angle, slope exposition and elevation were derived from the DEM; Lithology, soil deposits and faults were digitalized from the geologic maps; roads, streams and timber were extracted from Landsat image; precipitation was krigged from pluviometric measurement dataset. Different classes of thematic layers were assigned. A corresponding rating value as attribute information and an attribute map was generated for each data layer in the GIS. Landslide hazard areas were assessed and mapped using the landslide occurrence and permanent factor maps, by applying a probabilistic method with a logistic regression approach. The results of the analysis were verified using landslides location map, compared with the probability model. The resulting map can be used to mitigate this hazard, and to plan land use and urbanization.