Changes in Hydrological Risk Perception and Implications for Disaster Risk Reduction

Sammanfattning: Economic losses caused by hydrological extremes, such as floods and droughts, are exacerbating because of increased anthropogenic activities and global environmental changes. Understanding how individuals and communities interact with hydrological extremes thus becomes fundamental to develop effective strategies for disaster risk reduction. Risk perception plays an important role in determining how individuals and communities respond to the occurrence of an extreme event.  This thesis aims at addressing aspects of risk perception that remain largely unknown. They include: i) how flood risk perceptions change over time, ii) the role of previous experiences, and iii) how the perception of flood risk relates to the perception of other natural hazards, such as droughts. The work is based on survey data collected in different study areas – both in Italy and Sweden at the local and national scales – via longitudinal as well as cross-sectional approaches.  In relation to the three main objectives, this thesis found that: i) flood risk perceptions evolve differently over time depending on social groups; ii) different types of previous experiences with floods directly influence specific facets of risk perception, with knowledge deriving from the experience also playing an important role; iii) flood risk perception is heavily intertwined with drought risk perception. These results have policy and theoretical implications. Concerning the former, they can inform disaster risk reduction efforts in terms of risk communication and promote an integrated management of hydrological risk. As for the latter, they stress the importance of taking social heterogeneity into account when modelling the interaction between the social and the hydrological spheres, as this can influence the community’s response to extreme events. Fostering human adaptation to climate extremes is a priority. This thesis argues that adaptation can be achieved by promoting the awareness that not only are we at risk, but also that we have the means to address the risk.