Particular risk analysis case studies

The paper presents a fuzzy FMECA and makes a comparison between the new approach and the traditional one with the analysis of a case study. The results underline the main differences between the two methodologies, like the possibility of giving different weights to the risk factors (S, O D) or to define a risk profile which can vary according to the attitude to risk that a particular company or group of people may have, thus influencing priorities of intervention. 

Each of the case studies has been drawn from work carried out at the organisational level, as distinct from the project level. Each piece of work was motivated by senior management concern over liabilities or risk to which the particular organisation may have been exposed and a positive proactive desire to instigate remedial action where deficiencies were identified. Each case study involved some form of multi-perspective review, analysis, discussion of results, and remediation programme. 

The Champeyron Creek was chosen as a case study because of the availability of documentation on past debris flow events, of clearly visible tracks of past debris flow processes, and because of the presence of elements at risk. A geomorphological analysis of the basin, carried out through a multi-temporal photo interpretation, allowed to reconstruct the development of the debris flow in 3D. For this purpose also some photos of the period were used, together with interviews of witnesses and some specific field surveys. In particular the areas of debris supply for the 1981 event were identified. These latter corresponded to the extended screes visible in Fig. 24.2 and to some other areas prone to periodic rockfalls. The available DTM was adjusted to obtain the needed scale that allowed a simulation of the process. The characteristics of the debris flow mixture (solid fraction in % and dimensions of the largest boulders) were faithfully reconstructed, and this allowed to appreciate the dynamics of the process evolution and the mass transport capacity. Furthermore the expansion areas of the debris flow on the fan and the flow directions have been defined, which are essential components for the interpretation and numerical simulation of the 1981 event (Fig. 24.3). 

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