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Application of frequency ratio and likelihood ratio model for geo-spatial modelling of landslide hazard vulnerability assessment and zonation: a case study from the Sikkim Himalayas in India |
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| Authors: | L.P. Sharma Nilanchal Patel M.K. Ghose P. Debnath |
| Affiliation: | 1. Geo-Informatics , National Informatics Centre , Gangtok, Sikkim , India lp.sharma@nic.in;3. Department of Remote Sensing , Birla Institute of Technology , Mesra, Ranchi , India;4. Department of Computer Science , Sikkim Manipal Institute of Technology , Mazitar, Sikkim , India;5. College of Horticulture and Forestry , Central Agricultural University , Pashighat, Arunachal Pradesh , India |
| Abstract: | The Likelihood Ratio (LR) Model has been applied as an improvement upon the Frequency Ratio (FR) that computes the ratio of the percentage of the landslide pixels to the percentage of the non-landslide pixels instead of the total number of pixels used in the denominator as in case of the FR. The comparative assessment of the two techniques is made through spatial modelling of GIS vector data using the ArcGIS software. Two different Landslide Information Values were computed for each polygon element of the study area employing the two FR techniques that categorized the study area into five classes of vulnerability using natural breaks (Jenks) technique. Subsequently, vulnerability zonation maps were prepared showing the different levels of landslide vulnerability. The LR technique yielded significantly higher vulnerability assessment accuracy (77%) as compared to the standard FR (71%). |
| Keywords: | landslides vulnerability geographical information system frequency ratio likelihood ratio |