Patrice Langlois

Spatial risks and complex systems : methodological perspectives

Research on risk and industrial catastrophes question the complexity theories. Besides the concepts of complexity which lead us to reconsider concepts of risk, hazard and vulnerability, we propose to think about more practical aspects, for example the modelling of human behaviour in crisis situations. The link between concepts as critical self-organization, emergence, bifurcation, and the methods in the Distributed Artificial Intelligence (DAI) used to model them is however difficult. In this paper, we present ongoing analysis on the key concepts of risk science, such as hazards and catastrophes. We propose to enrich them with complex systems theories. First, we present methodological perspectives of the DAI, for example multi-agent systems, and compare them with other simulation methods used in the context of risks. Secondly, we present the MOSAIIC model (Modelling and Simulation of Industrial Accidents by Individual-Based methods) which gives possibilities to simulate the behaviour of individuals during an industrial accident. The project and the MOSAIIC model aim to explore the effects of a major industrial accident on public health. For instance, the emission and the spread of a toxic gas in an urban environment may be a serious danger for the human health. Thus we propose to study the consequences of this type of event in order to reduce the vulnerability of the populations. In the model, we emphasize both on spatial and behavioral dimensions (ie. mobility and perception of risk). All these questions lead us to use different methodologies of analysis. For example, concerning mobility, the daily traffic can be simulated at a meso scale: a road axis for example. In that way, we aim to simulate the global dynamics of the network from the modelling of flows on arcs of the network (modulated according to the time of day and the day of week). Yet, we plan to use classical models (for instance equilibrium models) because they give an ”average image” of the flows of vehicles on the arcs. Based on this first structural mobility, it is then possible to consider ”a change of level” regarding both the representation and the analysis: if a risk occurs or if a specific context disrupts the structure. As a consequence, from a management of flows on the arc, we turn to an analysis of the individual behaviours in a multi-agent system.