Landslide Mapping at the Watershed Level with OBIA — Case studies in the Baichi watershed, Taiwan
Date Issued
2012
Date
2012
Author(s)
Lahousse, Thomas
Abstract
Landslide mapping is a fundamental step to undertake landslide hazard and risk assessments. We designed two case studies in the Baichi watershed, Taiwan, to detect and map landslides with object-based image analysis (OBIA) techniques. We first developed a multiscale OBIA approach to map shallow landslides after Typhoon Aere in 2004. The detection performance reached 86.5% in training and 86% at validation. The method detected substantial number of landslides of all sizes. It could serve for mapping shallow landslides over large areas. We developed a second landslide detection scheme, based on a geographic object-based image change analysis (GEOBICA) methodology, to map landslide for multi-temporal inventories. The technique detected landslide at two dates, 2004 and 2008. Its detection performance was above 83% in both the training and validation watersheds. The technique also provided an account of landslide recovery, occurrence and persistence in the watersheds over the 4-year period. This methodology could serve to develop multi-temporal inventories, to check old landslide maps, and to identify landslide hotspots. Both techniques presented inherent limitations: site and image specificity of the classification thresholds in the first case, a restricted geographic scope and the necessary absence of shadow and clouds in the second case. We suggested further research directions in OBIA landslide mapping, to remedy current limitations and develop the potential of both methodologies. We finally recommended the use of OBIA in landslide hazard and risk assessment, beyond its current landslide mapping scope.
Subjects
OBIA
landslide mapping
multi-scale
GEOBICA
landslide detection
Taiwan
Type
thesis
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