Societal Flood Fatality Risk Assessments: An Advanced Probabilistic Method and Its Application to the Rhine-Meuse Delta (PAP014719)

Código

PAP014719

Autores

Karin M. de Bruijn, Ferdinand Diermanse, W. J. Klerk, Herman van der Most

Tema

Impact of climate change on flood risk

Resumo

In the Netherlands the possibility of societal disruption by floods plays an important role in the discussion on future flood risk management strategies. One of the indicators to assess societal disruption is societal flood fatality risk. Societal flood fatality risk is related to the probability of many fatalities during a single event. In deltas protected by flood defences, such as the Nether-lands, impacts of extreme events depend on the location and number of failures in the flood de-fences. The number and location of breaches depend on the failure probabilities of the embank-ments and the flow of river water through the breaches into the flood-prone areas. These flows reduce the river water levels and discharges and thus the probabilities of failures downstream. This retention effect proved to be very relevant. The assessment of flood risks in deltas protected by defences requires an advanced method which enables (1) the joint analysis of both storm surges and river discharges (2) the incorpora-tion of hydrodynamic interaction of loads and breaches at different locations to include the re-tention effect and (3) a complete and dynamic analysis of flood probabilities, breach growth, flood patterns, and flood consequences. The new developed method meets these requirements. The method results in FN curves which provide the probability of events with N or more fatali-ties. Results further include the potential loss of life (expected annual number of fatalities) and the contribution of the subareas to the total societal flood risk. The method also gives insight in which flood scenarios contribute most to societal disruption. To enhance the discussion on flood risk management strategies, the outcomes were compared with various views on potential toler-able risk levels from different countries and scientific fields. The paper discusses the method, its application to the Rhine-Meuse delta and the use of the out-comes in the discussion on future flood risk management strategies.