Isabelle Ruin:
From daily to crisis activities: Monitoring travel patterns in response to extreme weather stresses
According to the IPCC, flooding is the most widespread serious potential impact of climate change on human settlement. Vulnerability to floods can be thought as a function of exposure and adaptive capacity, and all three entities have been increasing in many areas. Therefore, in order to inform decision-makers, it is crucial to better understand what are the vulnerability factors but also to what extent individuals and societies are capable of adapting their way of life to their changing environment. Flash flood events are examples of the kind of extreme events that societies may have to face more often in the future. Flash floods are characterized by their suddenness, fast and violent movement, small scale and high level of damage. They are particularly difficult to forecast accurately and leave very little lead-time for warnings. Flash floods often surprise people who are in the midst of their daily activities, with particularly serious impacts when people travel across roads vulnerable to flooding. Overall, most of the people killed by flash floods are in cars. Nowadays, hydrometeorological research allows longer prediction lead-times and reduced uncertainty. However, social vulnerability remains high.
In this context, Isabelle’s research focuses on individual and organizational responses to warning and crisis situations by using a comprehensive, coupled natural—human system approach over time and space scales. The objective is to understand i) what cognitive and situational factors help individuals and communities to shift from normal daily activities to adapted crisis response and ii) what is the dynamic of this process compared to the one of the natural phenomenon. The research method uses both individual perception and behavioral intent surveys ("what if" type of survey) and actual behavioral data gathered in a context of post-event investigations. In the first case, findings are based on a large sample of questionnaire-surveys and cognitive mapping interviews used to assess individuals' a priori capacity to cope with flash flood conditions in different situations of the daily life. In the second case, the exploration of fatal circumstances and an individual’s spatio-temporal behaviors during deadly flash flood events allows to better characterize human exposure to such violent phenomenon. The integrated analysis of both approaches outcomes demonstrates that "at risk" travel patterns result in a mix of three factors: geographical and temporal exposure, cognitive understanding of risks on the road, but also daily family and professional constraints.
According to these first outcomes, motorists have shown to be vulnerable targets during flash floods both for perceptual reasons and daily constraints. Climate change with its forecasted increase in extreme weather events and expansion of urbanization leading to more and longer commuting will highlight the need to address this new kind of vulnerability. More behavioral verification surveys are needed to assess adaptive capacities of drivers in different weather conditions and monitor trends over the long term. Isabelle Ruin’s research aims to develop new methods to observe and monitor real-time individual and small-scale organizational responses to extreme weather stresses, especially focusing on mobility issues. Field experiments are currently under progress on selected pilot sites in Missouri, Texas, and in Southern France, in areas where road networks are subjected to frequent flooding. These studies are interdisciplinary collaborations that bridge the scientific and operational communities. Those collaborations take place in the framework of several projects ranging from local (FFRAP - Missouri), national (PREDIFLOOD - France) to international (HyMeX – Mediterranean countries) scales.
ASP Spotlight February 2009
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