Landslide Hazard Zonation around the route from Alemketema town to Ambat village, North Shewa, Ethiopia
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Date
2014-05
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Addis Ababa Universty
Abstract
In the Present study Landslide Hazard Zonation (LHZ) mapping around the route from Alem ketema town to Ambat village was carried out by applying Slope Stability Susceptibility Evaluation Parameter (SSEP) rating scheme. The main objective of the study was to prepare the LHZ map of the study area and to derive suitable recommendations based on the results of the study. Remote sensing and field survey was conducted to map the distribution of existing landslides and the factors that affect the landslide occurrences. Field measurements on structural discontinuities and observation on field manifestations for landslide and related slope instabilities was carried out. For digitizing, data processing, and analysis purposes, Arc-GIS 9.3 and Global Mapper 12 software were used. In applying SSEP rating scheme, the relative contribution of each of the intrinsic causative and extrinsic triggering factors were evaluated and ratings were assigned for each factor facet wise. The intrinsic parameters considered are; slope geometry, slope material, structural discontinuities, land use/ land cover and groundwater whereas the external triggering factors are; seismicity, rainfall and manmade activities. The sum total of all ratings for causative intrinsic parameters and external triggering parameters are represented as Evaluated Landslide Hazard (ELH) based on which the study area is divided into classes of hazard zones as per the SSEP rating scheme and the LHZ map of the study area was produced in GIS environment. The prepared LHZ map has identified two zones, namely High Hazard (66.9%) and Moderate Hazard (33.1%). Finally, LHZ map was overlaid by past landslide events data out of which 80.3% have fallen in High Hazard zone confirming the validity of the prepared LHZ map. Thus, the satisfactory validation confirms the rationality of considered parameters, the adopted SSEP technique, tools and procedures in developing the LHZ map of the study area.
Key words: Landslide Hazard Zonation (LHZ), Evaluated Landslide Hazard (ELH), Intrinsic, Extrinsic, Alem ketema, Ethiopia.
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Keywords
Landslide Hazard Zonation (LHZ), Evaluated Landslide Hazard (ELH), Intrinsic, Extrinsic, Alem ketema, Ethiopia.