Effect of the slope angle and its classification on landslides

Abstract

The preparation of landslide susceptibility maps is a complex process with regards to selection of study field, parameters, and methods. The phase after the determination of the landslide distribution in landslide susceptibility studies is selection of methods and parameters to be used. A review of approximately 1500 randomly selected publications revealed that it was necessary to select a parameter based on the area, in each study, the most preferred parameter was the slope angle. Generally, it was observed that automatic slope angle classifications were used in the preparation of landslide maps. Therefore, there is no standard in slope angle maps nor in the class range that is referenced when preparing them. In this study, class ranges and slope angle values of areas where landslides have occurred were determined from the 15 literature, and of these, 40 landslides areas were selected in Turkey and their slope angle maps were created. These were evaluated based on the slope angle classes determined in the published literature. The effects of slope angle on the landslide were determined, and an understanding was gained of how important it was to be careful when determining the classification of slope angle. When smaller class ranges were selected, different results were obtained suggesting that the selection of the range of classes are vital in the preparation of landslide susceptibility maps.