Landslide Mapping Using SqueeSAR Data
Abstract
SqueeSAR represents the most recent advancement of PSInSAR algorithm. By exploiting signal radar returns both from Permanent and Distributed Scatterers (PS and DS), it is able to detect millimetre displacements over long periods and large areas and to obtain a significant increase in the spatial density of ground measurement points. SqueeSAR analysis is complementary to conventional geological and geomorphological studies in landslide mapping over wide areas, traditionally based on aerial-photo interpretation and field surveys. However, whenever surface displacement rates are low (mm to cm per year), assessing landslide activity is difficult or even impossible without a long-term monitoring tool, as in the case of Deep-seated Gravitational Slope Deformations (DGSD), typically characterized by large areal extent and subtle surface displacement. The availability of surface displacement time series per each measurement point allows one to have both a synoptic overview, at regional scale, as well as an in depth characterization of the instability phenomena analyzed, a meaningful support to the design of traditional monitoring networks and the efficiency testing of remedial works. When data archives are available, SqueeSAR can also provide valuable information before the installation of any terrestrial measurement system. The Italian authorities increasing interest in the application of SqueeSAR as a standard monitoring tool to help hydrogeological risk assessment, resulted in a national project, Piano Straordinario di Telerilevamento (PST), founded by the Ministry of the Environment. The aim of the project was to create the first interferometric database on a national scale for mapping unstable areas. More than 12,000 ERS and ENVISAT radar scenes acquired over Italy were processed spanning the period 1992-2010, proving that, in less than ten years, radar interferometry has become a standard monitoring tool. Recently, many regional governments in Italy have applied SqueeSAR to map and monitor slope instabilities using ESA-ERS and RADARSAT images. One of the most successful was carried out in the Valle d'Aosta Region (NW Italy). The aim of the study was to support, verify and update the regional landslide inventory. The study covered a time span of about twenty years, from mid 1992 to late 2010. As many unstable areas of the region were reactivated in October 2000 by an intense meteorological event, the surface displacement data provided by traditional monitoring networks were compared at local scale with the displacement measured provided by SqueeSAR. This helped in better understanding the effects of the reactivation of the major landslides identified. Valle d'Aosta Region was the first authority to complete such a project at regional scale and make interpreted data officially available to professionals. Examples of integration of SqueeSAR data with other conventional geological and geomorphological studies at local and regional scale will be presented, with particular focus on DGSDs.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMNH51C..05F
- Keywords:
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- 1810 HYDROLOGY / Debris flow and landslides;
- 4337 NATURAL HAZARDS / Remote sensing and disasters