Mapping Landslide Hazard Zone and Modelling Slope Insatiability using Optical and PS-InSAR Technique

No Thumbnail Available

Date

2020-09

Journal Title

Journal ISSN

Volume Title

Publisher

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)

Citation