Mapping Landslide Hazard Zone and Modelling Slope Insatiability using Optical and PS-InSAR Technique
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Date
2020-09
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Addis Ababa University
Abstract
Landslides are geo-hazard that mostly occur in mountainous terrain and affect human lives and
damage infrastructures. They can be triggered by natural phenomena such as earthquakes, heavy
rains and volcanic eruptions. Construction works, legal and illegal mining, as well as the
unregulated cutting of hills (carving out land on a slope) caused most of the humaninduced
landslides.
In order to manage and mitigate their negative impact, landslide hazard
zonation mapping and slope instability assessment is crucial. In this study, landslide hazard
zonation mapping and deformation time series map for slope instability assessment were
implemented in Birbir Mariam area. The study area is in Southern region, around 47km northeast
of Arbaminch town. The main objective of the study was to carry out the mapping and zonation
of landslide hazards using analytical hierarchical process of remotely sensed data and assess slope
instability. In order to map landslide hazard zones, eight possible causative factors were studied.
These are slope, lineament density, drainage density, land-use and land-cover, elevation, lithology,
normalized difference vegetation index and aspect. These factors were compared using analytical
hierarchical process method to understand, which factors contribute a significant role for the
landslide occurrences and hence analyze the zones that are vulnerable to landslide. The result of
the analysis showed that, 15% (16.466km
) of the study area falls on very low hazard zone, 21.45
%( 23.547km
2
) within moderate hazard zone, 25.7 %(
28.221km
2
) under low hazard zone, 23 %( 25.25km
2
) within very high hazard zones.
For the slope instability assessment in the area, a time series map was generated from
Interferometric Synthetic Aperture Radar by making use of sentinel-1A data from 2014 to 2019.
The result from this persistent scatterer InSAR analysis showed that the average displacement
ranging from +5 mm/yr. to -5.4 mm/yr. with Positive values of the displacement shows that the
area is moving towards to line of sight while the negative values of the displacement shows the
area is moving away from line of sight. At last by integrating information obtained from optical
remote sensing, PS-InSAR and a landslide inventory map a conclusion is drawn that selected areas
in the north west, west, central and southern part of the survey area are prone to landslide hazards.
Description
Keywords
Landslide, Persistent Scatterer, Interferometric Synthetic Aperture Radar (InSAR)