LAMBERTI UNIBO-UPD ____________________________________________________________________________________ - 2.23.1 - TENTATIVE RISK MAP OF THE AREA OF CORTINA D’AMPEZZO (EASTERN ALPS, ITALY) A. Lamberti 1 , R. Genevois 2 , M. Berti 3 , S. Orlandini 4 , M. Papa 5 , A. Simoni 6 , P.R. Tecca 7 1 Professor, DISTART Università di Bologna, viale Risorgimento 1, 40136 Bologna Italy; E-mail lamberti@idraulica.ing.unibo.it 2 Professor, Dip. Geologia, Università di Padova, via Giotto 1, 35137 Padova Italy; E-mail rinaldo@geol.unipd.it 3 Phd, Dip. Scienze della Terra, Università di Bologna, via Zamboni 67, 40126 Bologna Italy: E-mail berti@geomin.unibo.it 4 Researcher, Dip. di Ingegneria, Università di Ferrara, Via Saragat 1, I-44100 Ferrara, Itlay; E-mail: stefano@idra.ing.unife.it 5 Phd student, DISTART Università di Bologna, viale Risorgimento 1, 40136 Bologna Italy; E-mail papa@idraulica.ing.unibo.it 6 Phd, Dip. Scienze della Terra, Università di Bologna, via Zamboni 67, 40126 Bologna Italy: E-mail simoni@geomin.unibo.it 7 Researcher, CNR-IRPI Padova, Corso Stati Uniti 4, 35127 Padova Italy: E-mail pia.tecca@irpi.pd.cnr.it Abstract A tentative technique to evaluate debris flow hazard in the area of Cortina d’Ampezzo (Eastern Alps, Italy) is presented. The method consists of a multisciplinary approach in which the geomorphological and hydrological characteristics of some representative basins are defined by aerial photo analyses, field survey and small scale studies, and the extension of debris flows is computed by numerical modelling. The computation of debris flow extension is based on a one-dimensional routing model of a Bingham fluid (COLD-1D) calibrated with data from actual debris flow events. Three return periods of the hydrograph of liquid discharge (namely 2, 25, and 200 years) were considered in the simulations of debris flow extension and the computed runout were compared with the extension of the trace left by past debris flows. If due account is given to uncertainty of observations, the moderately good agreement between computed and observed extensions validate the method applied, indicating that more frequent or extraordinary debris flows can be simulated. The evaluation of areas at risk, resulting from the overlap of the computed extensions with the vulnerable elements recognised in four sample areas, showed the main national road to be the structure most prone to debris flow damaging. 1 Introduction Debris flow occur in many different geomorphic and climatic condition and are initiated by a variety of mechanisms (Pierson et al., 1990; Cruden and Lu, 1992; Dietrich and Sitar, 1997; Debris Flow Triggering, thematic report, Vol.1). Regardless the triggering factor, however, the rapid mobilisation of failed masses and the tendency of debris flows to bulk up as they scour along their downstream paths enables relatively small volumes to become highly destructive forces.