The severe 1374 Rhine river flood event in present times

The severe 1374 Rhine river flood represents the largest flood in the past 1,000 years and exceeds the maximum discharge measured at Cologne, Germany, so far. The Dutch water policy is designed such that it should be able to withstand design discharges with a maximum return period of 100,000 years. The question arises whether the current flood protection measures along the Dutch Rhine river branches are sufficient to cope with an extreme event that is as severe as the 1374 flood event. In this study, a 1D-2D coupled model is set up to accurately simulate flood wave propagation with low computational cost. This model is used to simulate the consequences of the 1374 flood event in present times. The study shows that the maximum discharge along the Lower Rhine decreases significantly in downstream direction as a result of dike breaches and overflow. Therefore, the amount of water that reaches the Netherlands through the main channel is restricted to a maximum value. However, overland flow patterns influence the discharge partitioning of the Rhine river branches. Furthermore, the overland flow patterns change the most vulnerable areas in terms of flood risk.