Michele SANTANGELO, CNR IRPI, Italy
Santangelo CARDINALI, CNR IRPI, Italy
Francesco BUCCI, CNR IRPI, Italy
Federica FIORUCCI, CNR IRPI, Italy
Alessandro Cesare MONDINI, CNR IRPI, Italy
Landslides triggered by intense and prolonged rainfalls occur worldwide and cause extensive and severe damages to structures and infrastructures and loss of life. Obtaining even coarse information on the location of triggered landslides during or immediately after an event can increase the efficiency and efficacy of emergency response activities, possibly reducing the number of victims. In most cases, however, in the immediate aftermath of a meteorological triggering event, optical post-event images are unusable due to cloud cover. The increasing availability of images acquired by satellite Synthetic Aperture Radar (SAR) sensors overcome this limitation, because microwaves do not interact with water vapour. In the literature it has been shown that C-band Sentinel-1 SAR amplitude images allow the detection of known event landslides in different environmental conditions. In this work we explore the use of such images to map event landslides.
SAR backscatter products are generally represented by a grey tone matrix of backscatter values mainly influenced by (i) the projected local incidence angle, (ii) surface roughness, and (iii) the dielectric constant, used as a proxy for soil moisture. Landslides modify the local tone, texture, pattern, mottling and grain of the grey tone matrix. The defined interpretation criteria build on the well-established criteria applied to optical images. The same team of image interpreters mapped two large event landslides, the first with apriori knowledge as opposed to the second, where post-event optical image interpretation was done in the end. Maps obtained from SAR amplitude derived products were quantitatively compared to the maps prepared on post-event optical images, assumed as benchmark, by using a geometrical matching index.
Results of this study proved that Sentinel-1 C-band SAR amplitude derived products can be successfully used to map large event landslides, and that they should be further tested to prepare event inventories.
Mots clés : Event landslides|Sentine-1|C-band SAR|landslide mapping
A103873MS