Evaluation of Coherent and Incoherent Landslide Detection Methods based on Synthetic Aperture Radar for Rapid Response: A Case Study for Hokkaido Landslide

Damage mapping using SAR imagery has been studied for the past decades to support rapid response to natural disasters. Many researches have been developing coherent and incoherent change detection. However, their performances can vary depending on the types of the damages, characteristics of the scatterers and corresponding capability of algorithms. In particular, the coherence-based methods have been well known as promising detector over the urban area and high-coherence region, but still controversial over the low-coherence area as 2019 Hokkaido landslides. In order to understand the characteristics of landslide (damage) detectors for the low-coherence area and find the alternative and complementary method, we designed the coherence difference, coherence normalized difference, log-ratio, intensity correlation difference, and normalized differences of the intensity correlation assuming limited availability of dataset, and also developed the multi-temporal algorithms using the coherence, intensity, and intensity correlation. They are tested and evaluated using multiple polygons extracted from aerial photos. We were able to observe the multi-temporal intensity correlation method has the potential to detect the landslides over the low coherence region and all types of landuses.