Mapping of landslide susceptibility of coastal cliffs: the Mont-Roig del Camp case study

The weathered and fractured conglomerate cliffs of Mont Roig del Camp constitute a rock fall hazard for the surrounding pocket beaches and, therefore, for the population that frequent them, especially over the summer. Landslide susceptibility of the cliff has been assessed using the Rock Engineering System method (RES). The determinant and triggering factors considered in this study include: wave exposure, shoreline variations, cliff height, cliff slope, geotechnical quality of the rocky mass, superficial runoff and cliff orientations favoring landslides. Geographic Information Systems (GIS) have been employed to facilitate the information analysis and generate new susceptibility maps. The quality of the rock mass and cliff orientation are the most interactive factors for the stability of the cliff. However, shoreline variations and surface runoff are the most dominant factors in the system. Thus, the quality of the rock mass has been determined to be a basic variable in the cliff characterization because of its high dependence on the variations of the remaining factors. The landslide susceptibility map depicts a predominance of surfaces with moderate degrees of susceptibility concentrated mainly in the headlands, where the combined actions of subaerial and marine processes control the weathering and eroding processes. Therefore, the landslide susceptibility assessment based on this methodology has allowed the identification of hazardous areas that should be considered in future management plans.