Comparison of Debris flow Depositional Scenarios using different DTMs.

The paper reports numerical simulations of two debris flows occurred in 2000, in the middle part of the Stura di Valgrande valley (Lanzo, North-Western Italy). A Cellular Automata Model, based on the dilatant fluid constitutive law, and two different Digital Terrain Models (DTM) were employed. The first simulations were performed with a DTM dated 1999 (grid 10x10 m) and reproducing the site topography before the events. The other simulations were carried out with a DTM dated 2011 (from Light Detection And Ranging surveys) with a grid 5x5 m. Although the results obtained with a post event DTM can be affected by morphological changes, however the agreement with in site evidences seems to be more consistent. The rheological parameters calibrated with back analyses for the two DTMs are different. These results seem to indicate the influence of the topography accuracy for the calibration of the rheological parameters