Floods and Societies: the Spatial Distribution of Water-related Disaster Risk and its Dynamics

This opinion article posits that the current lack of understanding of the dynamic interactions among the different components of risk (e.g., hazard, exposure, vulnerability, or resilience) is one of the main obstacles for the implementation of effective risk prevention measures. In state‐of‐the‐art methods for risk assessment, natural and social systems are typically treated separately by using different approaches. In flood risk studies, for instance, hydrological scientists typically focus on flood hazard, whereas socioeconomic scientists mainly examine the exposure, vulnerability, or resilience to flood events. However, we argue that these different components are deeply interconnected: for example, changes in flood hazard often trigger changes in vulnerability, and vice versa. These interconnections between the different components of risk remain largely unexplored and poorly understood. This lack of knowledge is of serious concern as it limits our ability to plan appropriate risk prevention measures. To design flood protection structures, for example, current methods can indeed provide quantitative assessments of the corresponding risk reduction associated to the reduced flood hazard. Nevertheless, traditional methods cannot estimate how, and to what extent, the reduced frequency or magnitude of floods might trigger increases of exposure or vulnerability to flooding (e.g., ‘levee effect’). Thus, while many progresses have been made in the static assessment of flood risk, the dynamics of risk are still poorly investigated. We think that this is a major issue in a rapidly changing world, and we therefore propose a transdisciplinary research agenda as a possible way out