Flow Depths and Velocities across a Smooth Dike Crest

Thiscontributionproposesasystematicanalysisoftheovertoppingprocessatdikes,focused on the statistical description of the extreme flow characteristics across the dike crest. The specific objective of the analysis is the investigation of structures subjected to high run-up levels and low freeboards, under severe or extreme conditions that are likely to occur in the future due to climate change. Theadoptedmethodologyisbasedonthecollectionofnewexperimentalandnumericaltests ofwaveovertoppingatsmoothdikesatvariouscrestlevels. Thereliabilityofthenewdataischecked in terms of average overtopping discharge and wave reflection coefficient, against consolidated predicting methods from the literature. An update and refitting of the existing formulae for the prediction of the extreme flow depths and velocities at the dike off-shore edge is proposed based on the experimental and numerical outcomes. The dynamics of the overtopping flow propagation along the dike crest under breaking and non-breaking waves, in emerged and submerged conditions, is investigated. Guidelines to update the state-of-the-art formulae for a more cautious estimation of the water depths and the velocities of propagation of the flow in the landward area are provided.