COMPARING SCOOP3D AND GIS-TISSA MODELS FOR SLOPE STABILITY ANALYSIS IN IDUKKI, KERALA, INDIA

Abstract

Landslides are the most destructive hazard in the mountainous Idukki district in the State of Kerala, India. Therefore, evaluating the possible occurrence of landslides and analyzing the factors that trigger failure is an essential part of a reliable landslide assessment. Physics-based models are commonly used to determine potential landslide susceptible areas in terms of Factor of Safety (FS). Recent years have seen the use of physics-based methods for regional-scale landslide susceptibility analysis using geospatial tools. In this study, we compare two physics-based models using the same data from Idukki. The two models are the Geographic Information System-Tool for Infinite Slope Stability Analysis (GIS-TISSA) that utilizes the infinite slope stability analysis, and the Scoops3D algorithm that uses limit-equilibrium analysis. The significant difference between these two physics-based models is that the GIS-TISSA assumes a shallow failure surface parallel to the slope angle. In contrast, the Scoops3d evaluates deeper rotational failure surfaces. The results from these two physics-based landslide models are critically evaluated with the existing landslide database to verify the validity of these methods for Idukki. The results show that the GIS-TISSA model is more effective in landslide-prone area mapping, with 41% of the actual landslides identified as unstable. For the Scoops3D, the same output only identifies 16% of the landslides. The GIS-TISSA model matched 87% landslides with the FS values less than 1.7 within unstable-medium stable classes, while the Scoops3D model shows 62% landslides.