Numerical Analysis of Rainfall‐Induced Landslides and Stability Assessment Along the Bonga‐Mizan Road Section, Ethiopia

Landslides along the Bonga‐Mizan road segment in Ethiopia have been persistent despite previous mitigation measures, disrupting socioeconomic activities and increasing maintenance costs. This study aims to investigate the underlying factors contributing to the recurrent landslides and identify practical mitigation strategies. While factors such as rainfall, groundwater, material properties, geology, and topography have been acknowledged in prior studies, the specific impact of rainfall and groundwater on slope stability remains underexplored, particularly in this region. The research evaluates the behavior and stability of slopes at two critical locations: stations 4 + 400 and 197 + 216 km. The findings reveal that rainfall and groundwater significantly reduce the factor of safety (FOS) and increase deformation, with FOS values decreasing from 1.53 to 2.04 under dry conditions to 0.98 and 0.91 under wet conditions, respectively. Deformation patterns and critical slip surfaces at depths of 11 and 10 m were also observed. These results underscore the dominant role of water‐related factors in triggering landslide instability. The study suggests that enhanced drainage systems, including both groundwater and surface management, are essential for mitigating landslide risks in the area. The findings offer valuable insights to improve the resilience of road infrastructure in landslide‐prone regions, thereby contributing to more effective disaster management and road maintenance strategies.