The management of risk to sudden natural, technological or man-made hazards needs to consider potential harm to people. Commonly, the available information about exposed population is static as it is based on night-time residential locations. People, however, are mobile, and therefore their potential presence in a hazard zone is a function of time and space (Smith, A., 2015, Bhaduri et al., 2007, Martin et al., 2015). The objective of this work is to improve risk assessments to sudden hazards by developing high-resolution population data for different points in time for the area of the Autonomous Province of Bolzano (South Tyrol). The work was carried out with support of the local Civil Protection authorities.
The study area of South Tyrol is a mountainous region located in the Alps in northeast Italy. Because of its steep terrain the entire region is prone to natural hazards, such as landslides, floods, rockfalls and avalanches. In a daily cycle, people commute from their places of residence to their workplaces in regional centres. In an annual cycle, there are significant differences and peaks in the presence of people due to tourism and seasonal foreign workers employed in the agricultural sector.
In this research, we used a bespoke software developed by the University of Southampton. Using Surfacebuilder 247, we modelled population distribution in the study area at 100m resolution for representative times over the day and the year. We populated the model with residence-, workplace-, education-, health- and leisure- location information. Based on literature review and experts opinion we determined capacities, time profiles and catchment areas for each of these locations. The results are visualised within a Geo Information System and represent the variations of population’s mobility at selected times and dates. We integrated this improved exposure layer into a so far static risk assessment related to a potential dam-outburst flood in a mountain valley (municipalitiy of Prad am Stilfserjoch/Prato allo Stelvio). The results show significant variations in the risk of harm to people for different times over the day and over the year. The product can contribute to improved risk management by the civil protection but also to an improved spatial planning and traffic management.