NWO ICOWEX – Impacted by Coincident Weather Extremes
In January 2012 strong Northerly winds, associated with two major storm systems, resulted in very high water levels near the coast of Groningen. Persistent rainfall had occurred over the area in the days prior to the event. This coincidence led to a hazardous situation, as it was not possible to drain the water into the Wadden Sea. Flooding threatened Groningen and dikes had to be broken temporarily to give more space to the water. Importantly, neither the rainfall nor the winds would have caused major problems had they occurred at different times.
This “compound” event renewed discussion on the safety of our nation to flooding and rising sea levels. It demonstrated the urgent need for rigorous statistical knowledge and sound dynamical understanding of such events. In much the same way the 1953 historic flooding of Zeeland had triggered the formulation of a national Deltaplan and the construction of the Deltaworks. Since then knowledge has greatly improved, however with a focus on single catastrophic events, rather than on coinciding events such as in Groningen.
ICOWEX contributes to this challenging topic, by studying three aspects of extreme events that increase their impact. These are the persistence, clustering and compound nature of extreme events. We propose to study their present-day occurrence and predictability, as well as possible changes under scenarios of future climate. With sea level rising and the new Deltaplan-2014 having just appeared, this proposal provides a timely and unique opportunity to contribute to the safety of the Dutch Delta.