Participatory Causal Loop Diagrams Building for Supporting Decision-Makers Integrating Flood Risk Management in an Urban Regeneration Process

Several modeling tools commonly used for supporting flood risk assessment and management are highly effective in representing physical phenomena, but provide a rather limited understanding of the multiple implications that flood risk and flood risk reduction measures have on highly complex systems such as urban areas. In fact, most of the available modeling tools do not fully account for this complexity-and related uncertainty-which heavily affects the interconnections between urban systems evolution and flood risk, ultimately resulting in an ineffective flood risk management. The present research proposes an innovative methodological framework to support decision-makers involved in an urban regeneration process at a planning/strategic level, accounting for the multi-dimensional implications of flood risk and of different flood risk management strategies. The adopted approach is based on the use of System Thinking principles and participatory System Dynamics modeling techniques, and pursues an integration between scientific and stakeholder knowledge. Reference is made to one of the case studies of the CUSSH and CAMELLIA projects, namely Thamesmead (London), a formerly inhospitable marshland currently undergoing a process of urban regeneration, and perceived as being increasingly vulnerable to flooding. It represents an interesting opportunity for building a replicable modeling approach to integrate urban development dynamics with flood risk, ultimately supporting policy and decision-makers in identifying mitigation/prevention measures and understanding how they could help achieve multi-dimensional benefits (e.g., environmental, social and economic). Flooding is one of the most harmful natural disasters that cities may encounter, particularly considering the impacts of climate change and the highly dynamic evolution of urban areas. As traditional modeling approaches tend to provide an effective yet simplified view of flood risk assessment and management in urban areas, decision-makers need integrated approaches that can capture on the one hand the complex implications of flood events and flood risk management strategies in urban areas and, on the other hand, the impacts of urban development on flood risk. This work proposes an innovative approach based on qualitative modeling tools for urban flood risk analysis, which also incorporates the knowledge provided by local stakeholders. Although applied to a specific case study, the approach can be implemented in different contexts. The results highlight the importance of integrating urban dynamics and flood risk, especially in the preliminary identification of mitigation/prevention measures. However, further activities have already been started to support their operationalization. Stakeholders' knowledge can provide relevant insights into the urban dynamics related to flooding Causal Loop Diagrams support better integrating flood risk management in evolving urban systems Behavior Over Time graphs support scenario analysis including the impact of prevention/mitigation measures