Simulating Spatial and Temporal Flood Risk Dynamics with a Coupled Agent-Based and Hydraulic Model

Abstract: Floods are one of the most costly natural hazards worldwide, affecting millions of people every year. Flood risk management is of global concern, and a deeper understanding of dynamic flood risk development is needed. Currently,vulnerability and exposure are often assumed to be constant in quantitative flood risk assessments, which does not reflect patterns observed in real life. In fact, flood protection measures on individual and community level can induce changes in both vulnerability and exposure, as well as alter river and floodplain hydraulics. The human-flood system is complex, incorporating two-way interactions between both subsystems. To build up these dynamics from the bottom up with a focus on the role of the individual, an agent-based model was combined with a hydraulic model. It was shown that this coupled model is capable of replicating levee and adaptation effects which are commonly knownto occur in the context of river floods and flood protection measures. Moreover,the new modeling approach can explicitly simulate the spatial distribution of flood risk which allowed for an analysis of conflicting interests in urban and rural areas. Here, model outcomes suggest that a shift of flood risk from high-value urban to lower-value rural areas can reduce system-wide flood losses. However, decreasing flood awareness in the city will push population growth rates, and discontent in rural areas might nally induce a shift of higher floodrisk back to the urban area. In the end, one low-probability high-intensity event might cause a disastrous outcome.