An updated sediment source areas inventory in the Rio Cordon catchment (Dolomites)

Abstract

This study presents an inventory of sediment source areas updated to 2016 of the Rio Cordon catchment, a small headwater basin located in the Eastern Italian Alps. The aim of the 2016 inventory was to update an old sediment source areas dataset dating back to 2006, built using LiDAR-derived geomorphometric parameters interpretation and field survey, in order to evaluate the geomorphic changes occurred in the last 10 years in the catchment. The new inventory wasrealized by means of an extensive field survey campaign conducted with a mobile GIS mounted on a rugged notebook integrating a GPS receiver. Pictures of individual or collective sediment source areas were also acquired in order to integrate the GIS dataset and to better define their current status of activity. The images were also used for a comparison with the images acquired in 2006 to identify the evolution or stabilization of each sediment source area. The identification and delimitation of large and/or unreachable areas was carried out in the office by interpreting aerial photo images (Bing satellite images and Web Map Services for AGEA 2009-2012 aerial photographs,compared with the old LiDAR-derived high resolution images used for the 2006 sediment source inventory). The comparison with the previous inventory shows that several old sediment sources resulted totally stabilized indicating a general decrease of erosion processes in the catchment. In contrast, some new sediment source areas were identified. They were mainly related to a very recent rock fall that took place in July 2016 in the Lastoni di Formin group and many new shallow landslides were found in the upper part of small Rio Cordon tributary where a small debris flow event occurred in 2012.