Landslide hazard zonation and evaluation around Debre Markos town, NW Ethiopia—a GIS-based bivariate statistical approach

Abstract

The main purpose of this study was to perform landslide hazard zonation and evaluation around Debre Markos town, Northwest Ethiopia. This was achieved using a GIS-based bivariate statistical technique. Initially, a landslide inventory map containing information on past and active landslide locations was prepared. In this study, eight conditioning factors, including slope material (lithology and soil mass), elevation, aspect, slope, land use, land cover, curvature, distance to fault, and distance to drainage, were identified and integrated with the ArcGIS platform. Data were collected from field mapping, satellite images, and digital elevation models. All conditioning factors were statistically analyzed to determine their relationship to previous landslides. The hazard map revealed that 17.15% (40.60 km2) of the study area falls under no hazard zone, 25.53% (60.45 km2) in low hazard zone, 28.04% (66.39 km2) in moderate hazard zone, 18.93% (44.83 km2) in high hazard zone, and the remaining 10.36% (24.54 km2) in very high hazard zone. The validation of the landslide hazard zonation map shows that 94% of past landslides fall in high or very high hazard zones, while 3% fall in moderate hazard zone, 2% fall in low hazard zone, and 1% fall in no hazard zone. The validation of the LHZ map thus, reasonably showed that the adopted methodology produced satisfactory results. The delineated hazard zones may practically be applied for the regional planning and development of infrastructures in the area. The results also indicated that slope angle, distance to fault, distance to drainage, and slope material types were statistically significant in controlling the landslides.