Landslides identification based on polarimetric decomposition techniques using Radarsat-2 polarimetric images

Abstract

In this article, a method for landslides identification based on polarimetric decomposition techniques and the Wishart classifier is presented. Several parameters of Cloude decomposition and Freeman–Durden decomposition are introduced to analyse the radar scattering mechanisms over landslides and their surroundings. By analysing the polarimetric characteristics of three typical landslides triggered by the 2008 Wenchuan earthquake, the result demonstrates that the dominant scattering mechanism of the landslides is the surface scattering component, and the scattering entropy is centred between 0.6 and 0.8. Besides, the result also indicates that the surroundings show the dominance of the volume scattering component, whereas their scattering entropy is almost similar to the landslides. According to the experimental analysis, two temporal SAR images are classified into nine categories, respectively, based on polarimetric decomposition techniques and the Wishart classifier. By comparing the surface scattering areas in the second image with the volume scattering areas in the first image, and combining the scattering entropy, the new slope failures are obtained using the change detection method. In addition, in order to reduce the errors introduced by the registration and noises, the identification map of new landslides is processed by the morphology algorithm. Finally, a field experiment is carried out to verify the existence of the new slope failures and thereby the result shows the validity of the proposed method.