The multi-layer safety approach and geodesign: exploring exposure and vulnerability to flooding

Lately, flood risk reducing measures can be assessed quicker and more precise due to increasing computing power and advanced conceptualization of geo-information and geodesign. For flood risk, the multi-layer safety approach is developed to support analysis and assessment of preventive and impact reducing measures. In this multi-layer safety approach, risk is calculated as probability of occurrence of a flood times the consequences of a flooding. The impact of a flooding equals the exposure of capital and people in the flood risk area times the vulnerability for flooding of capital and people. Complexity of flood risk reduction increases when flood risk managers incorporate these consequences. The use of geodesign to assess flood risk reducing measures in such a complex approach, is highly beneficial. We conceptualize flood risk consequences to illustrate the use of geodesign, and calculate inundation depth, velocity and timing of a flood at specific locations in the case ‘Rivierenland’. We assess evacuation possibilities, safety on first and second floors of health care institutions and effects of flood arrival times on evacuation capacity planning. Even the rough information provided by our case gives flood risk managers essential insight in the timing and impact of flooding events, and the possibilities to timely and effectively evacuate healthcare institutions. Advancement of geo-information and geodesign provides the opportunity to design more effective capacity planning schemes, to improve decisions about evacuation strategies and to a more robust design of buildings and critical (infra)structures with respect to flood risk.