A first assessment of the effect of storm climate trends and uncertainties on Dutch levee design

This paper presents a first assessment of the effect of uncertainties in storminess on Dutch levee design. An expert panel was consulted to define a range of plausible trends and uncertainties in extreme wind climate. The design and assessment of the Dutch levees are carried out with official probabilistic tools, which have been developed in the legal assessment and design instrumentation. According to these new risk-based assessment practices (Slomp et al., 2016), uncertainties in hydraulic loads must now explicitly be accounted for, since they can have a major effect on the design and assessment of the water defences.

Three scenarios were defined with variations of the current wind climate, including changes in wind speed high percentiles and in wind direction. For the defined scenarios probabilistic computations were carried out to determine the effect of the wind statistics variations on the water level, wave loads, and required levee height along the Dutch lakes and coast. Given the large impact of the considered changes, it is first recommended to carry out a more robust assessment of the uncertainties in future storm climate and to measure and monitor evolution of future wind speeds.