Landslide susceptibility mapping by frequency ratio and fuzzy logic approach: a case study of Mogods and Hedil (Northern Tunisia)

The aim of this study is to produce a landslide susceptibility map in Mogods and Hedil using the fuzzy logic method. To increase the objectivity of the approach, the fuzzy membership was calculated using the frequency ratio (FR). Nine factors were considered for landslide control, including slope, aspect, plan curvature, profil curvature, distance from faults, distance from rivers, land use, precipitation, and lithology. The frequency ratio was used to calculate the fuzziness of each factor, and these results were then applied to the fuzzy operators to produce the landslide susceptibility map. The selection of the susceptibility map closest to reality was based on the spatial distribution of landslides in each susceptibility class of each fuzzy operator and on the application of the receiver operating curve (ROC). The results of the area under curve (AUC) analysis show that the GAMMA operator (0.90) provided the most accurate prediction of the landslide susceptibility map, as indicated by the prediction accuracy of the model (0.766). The study area was classified into four classes using Jenks natural fracture classification method: low susceptibility zone, moderate susceptibility zone, high susceptibility zone, and very high susceptibility zone. The use of the fuzzy GAMMA operator for landslide susceptibility mapping gave a very satisfactory result with a reliability rate of 76.6%.