Improvement of vulnerability curves using data from extreme events: debris flow event in South Tyrol

Alpine hazards such as debris flow, floods, snow avalanches, rock falls, and landslides pose a significant threat to local communities. The assessment of the vulnerability of the built environment to these hazards in the context of risk analysis is a topic that is growing in importance due to global environmental change impacts as well as socio-economic changes. Hence, the vulnerability is essential for the development of efficient risk reduction strategies. In this contribution, a methodology for the development of a vulnerability curve as a function of the intensity of the process and the degree of loss is presented. After some modifications, this methodology can also be used for other types of hazards in the future. The curve can be a valuable tool in the hands of local authorities, emergency and disaster planners since it can assist decision making and cost-benefit analysis of structural protection measures by assessing the potential cost of future events. The developed methodology is applied in two villages (Gand and Ennewasser) located in Martell valley, South Tyrol, Italy. In the case study area, buildings and infrastructure suffered significant damages following a debris flow event in August 1987. The event caused extensive damage and was very well documented. The documented data were used to create a vulnerability curve that shows the degree of loss corresponding to different process intensities. The resulting curve can be later used in order to assess the potential economic loss of future events. Although the validation process demonstrated the reliability of the results, a new damage assessment documentation is being recommended and presented. This documentation might improve the quality of the data and the reliability of the curve. The presented research has been developed in the European FP7 project MOVE (Methods for the Improvement of Vulnerability Assessment in Europe).