Object-Based Geomorphological Mapping: Application on an Alpine Deep-Seated Gravitational Slope Deformation Contest (Germanasca Valley, Western Alps—Italy)

Abstract

This research reports the use of a new method of geomorphological mapping in GIS environments, using a full-coverage, object-based method, following the guidelines of the new geomorphological legend proposed by ISPRA–AIGEO–CNG. This methodology is applied to a tributary valley of the Germanasca Valley, shaped into calcschist and greenschist, of the Piedmont Zone (Penninic Domain, Western Alps). The investigated sector is extensively affected by dep-seated gravitational slope deformation (DSGSD) that strongly influences the geological setting and the geomorphological features of the area. The mapping of these gravitational landforms in a traditional way creates some difficulties, essentially connected to the high density of information in the same site and the impossibility of specifying the relationships between different elements. The use of the full-coverage, object-based method instead is advantageous in mapping gravitational evidence. In detail, it allows for the representation of various landforms in the same sector, and their relationships, specifying the size of landforms, and with the possibility of multiscale representation in the GIS environment; and, it can progressively be update with the development of knowledge. This research confirms that the use of the full-coverage, object-based method allows for better mapping of the geomorphological features of DSGSD evidence compared to classical representation.

Tectonic architecture of the northern Dora-Maira Massif (Western Alps, Italy): field and geochronological data

“…While the former are covered by a dense forest, the latter are frequently subjected to landslides, which can have very large proportions (the so-called deep-seated gravitational slope deformation DSGSD; e.g. Forno et al, 2022 ). In the study area, glacial erosion and coeval glacial deposits (i.e.…”

The Lac Fallère Area as an Example of the Interplay between Deep-Seated Gravitational Slope Deformation and Glacial Shaping (Aosta Valley, NW Italy)

“…In the context of a DSGSD, it is not uncommon for a glacial landform to be fragmented into slabs by one or more minor scarps (e.g., in the Pointe Leysser DSGSD) [41], while the preservation of a gravitationally displaced moraine is unusual (e.g., Rodoretto DSGSD in the Chisone Valley) [42] or more difficult to recognise (e.g., Arp Vieille DSGSD in the Valgrisenche) [43].…”

“…GeoHazards 2024, 5, x FOR PEER REVIEW 2 of 28 DSGSD in the Chisone Valley) [42] or more difficult to recognise (e.g., Arp Vieille DSGSD in the Valgrisenche) [43]. More generally, both dislocation of the pre-DSGSD glacial landforms and sediments, such as glacially sculpted valley sides and moraines displaced by minor scarps or counterscarps, and glaciers that enlarged syn-glacial trenches and levelled minor scarps, suggest an interplay of glacial and gravitational processes.…”

The Lac Fallère Area as an Example of the Interplay between Deep-Seated Gravitational Slope Deformation and Glacial Shaping (Aosta Valley, NW Italy)

“…in the P. Leysser DSGSD) [41], while the preservation of a gravitationally-displaced moraine is unusual (e.g. Rodoretto DSGSD in the Chisone Valley) [42] or more difficult to recognise (e.g., Arp Vieille DSGSD in Valgrisenche) [43].…”