Reducing Subjectivity in Landslide Hazard Zonation Method: An Integrated Methodology

Abstract This study was conducted in Sheko District, Southwestern Ethiopia. The area has been experiencing recurrent landslide problems for several years. Due to the severity of these slope instability issues, this study was undertaken. The primary objective of the study was to evaluate landslide hazard using a new methodology and to validate its efficiency. An integrated Slope stability Susceptibility Evaluation Parameter and Geographic Information System based statistical Value approach was employed. Facet-wise field measurement and observations were made, and ratings for each parameter class were assigned based on the prevailing conditions on individual facets. By establishing the density relationship between past landslides in the study area computation of hazard index and modifying rating to come up with the new methodology rating has been done. The evaluate landslide hazard map produced by the integrated approach classifies the study area into four zones, low hazard, moderate hazard, high hazard and Vey high hazard zones. Out of a total of 303 facets evaluated using the integrated approach, covering an area of 0.469 km2, 8 facets are classified as falling under the low hazard zone, 232 facets are classified as falling under the moderate hazard zone, 62 facets classified as high hazard zones with area coverage of 27.064\(\:{\:\text{K}\text{m}}^{2}\), which count for approximately 25.7% of the study area, one facet (Facet 286) classified as very high hazard zone with area coverage of 0.223\(\:{\:\text{K}\text{m}}^{2}\), approximately 0.21% of the study area.