On August 29th 2003 many debris flows were activated along different streams of the Fella
river basin (North–East Italy). After that huge event a program of debris flow risk analysis was
started and through the use of FLO-2D software, a new outline of the hazardous areas was
obtained. In the last years, part of a PhD research project was addressed to define a quick field
and laboratory survey methodology suitable to obtain reliable rheological parameters and to
reproduce debris flow scenarios in the absence of back analysis. An example of the
methodology is presented, including grain-size and rheological analysis on samples of a
watershed located in left side of the Fella river, the reconstruction of its DTM starting from
detailed laser scanner data (Civil Defense of Friuli Venezia Giulia Region) and the updating of
the morphometric parameters in virtue of the more detailed data. For the present research, a
comparison between previous simulated scenarios and those obtained through the introduction
of new basic data was provided. In particular, the simulations based on the parameters
collected after the 2003 event on the DTM of 2003 were used as back analysis, whereas new
simulations were performed using the rheological parameters derived from samplings and
laboratory analyses realized during 2013 on the DTMs of 2008, in order to create future
possible flooding scenarios on the actual morphology and to test the effectiveness of the
mitigation measures, built up after the 2003 event.
