Fanti, R.

Frodella, W.

Morelli, S.

Pazzi, V.

English

Florence Research

Geophysical Research AbstractsVol. 20, EGU2018-5228, 2018EGU General Assembly 2018© Author(s) 2018. CC Attribution 4.0 license.Analysis of LiDAR derived DEM geomorphometric parameters to assessthe kinematic behaviour of a DSGSDVeronica Pazzi, Stefano Morelli, William Frodella, and Riccardo FantiUniversity of Firenze, Department of Earth Sciences, Firenze, Italy (veronica.pazzi@unifi.it)Slope instability processes in mountainous areas are characterized by a complex interaction between differentlithological, geomorphological, structural features, and processes. Deep-seated gravitational slope deformations(DSGSDs) are largest non-catastrophic slow rock-slope deformation, that until recently, under the present climaticcondition, were considered inactive and not hazardous phenomena. Generally, the entire slope affected by DSGSDcan be differently deformed with millimetric-displacements, that often cannot be observed by means of fieldsurveys. This can generate in the risk management of these phenomena non-exhaustive safety awareness strategies,which on the contrary often focus only on the more short-period localized hazardous effects. DSGSD, in fact,evolve at different time scales and could present sudden and rapid secondary minor landslides. Therefore, acomplete risk assessment strategy must comprise also the analysis of deep-seated impulsive phenomena. This typeof behaviour can be observed effectively only using high-resolution data obtained by means of advanced remotesensing techniques. Among all these technologies applied in landslide analysis the more effective in the DSGSDstudies are: ground-based interferometric radar (GB-InSAR) and Light detection and ranging (LiDAR).On 4th November 2010, after the October-November 2010 rainfalls, the Rotolon deep-seated gravitationalslope deformation (Vicentine Pre-Alps, NE Italy) reactivated with a sudden ground movement. A 450,000 m2mountainous area moved some meter downslope, but the undeniable signs were only connected to the triggeringof a debris flow from the bulging area detrital cover, and the presence of a continuous perimeter fracture nearthe crown area. Therefore, the 2010 event apparently was limited to secondary and localized phenomena, so thatan early-warning system (a GB-InSAR and an automatic monitoring network composed by extensometers and arobotic total station) were installed to monitor the residual risk. Moreover, a 3D landslide runout numerical modelwas performed to identify the source and impact areas of further debris flow, the flow velocity, and the depositdistribution within the Rotolon creek valley. Nevertheless, the analysis of the DEMs parameters, derived from twodetailed LiDAR surveys (2x2 m), performed just few days before and after the event, allowed to highlight somemorphological changes occurred after the 2010 reactivation, and associable not only to shallow movements butalso to deeper ones. The kinematic behavior reconstruction and the geomorphometric parameters analysis wereperformed in a GIS environment, integrating morphometric terrain parameters (slope, aspect, surface roughness,topographic wetness index, hillshade, and curvature) with the results of an accurate geomorphological field survey.This analysis pointed out not only shallower movements in the bulging area, but also regular morphologicalchanges occurred in six main areas of the whole DSGSD, and connected to deeper continuous displacementsalong the maximum slope gradient, confirming the DSGSD reactivation. Moreover, the displacements connectedto the DSGSD reactivation did not cease immediately, in particular far from the break/crown zone (as shown bythe integration of the morphometric terrain parameters and the GB-InSAR data), but continued with very slowdeformations until the new equilibrium was reached, testifying the impulsive behavior of the landslide.

Analysis of LiDAR derived DEM geomorphometric parameters to assess the kinematic behaviour of a DSGSD

https://flore.unifi.it/bitstream/2158/1144945/1/Pazzi%20et%20al%20GRA%20vol%2020EGU%202018.pdf

Analysis of LiDAR derived DEM geomorphometric parameters to assess the kinematic behaviour of a DSGSD

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