Mapping Landslides and Modeling of Slope Instability via Optical and PS-InSAR Techniques: A case study in the Birbir Mariam Area of the Southern Region, Ethiopia

Landslides are geohazards that frequently occur in mountainous regions, posing a threat to human lives and causing damage to infrastructure. They can be triggered by natural phenomena such as earthquakes, heavy rainfall and volcanic activities as well as human interference. In this study, landslide hazard zonation and deformation time series mapping were used to study slope instability in the Birbir Mariam area, which is located 47 km northeast of Arba Minch town in southern Ethiopia. The objective of this study was to carry out mapping and zonation of landslide hazards via an analytical hierarchical process and persistent scatterer interferometric synthetic aperture radar techniques. In this study, landslide hazard zones were mapped by analyzing eight key causative factors: slope, lineament density, drainage density, land use and land cover, elevation, lithology, normalized difference vegetation index (NDVI), and aspect. The results of the analysis revealed that 25.7% (28.221 km2) were within a high hazard zone and 14.85% (16.306 km2) were within very high hazard zones. The results from persistent scatterer interferometric synthetic aperture radar analysis revealed that the average displacement ranged from + 5 mm/yr. to -5.4 mm/yr. The positive value of displacement indicates that the area is moving toward the line of sight, whereas the negative values of displacement indicate that the area is moving away from the line of sight. The results indicate that the northwestern, central and southern parts of the area are prone to landslide hazards.