Wave breaking and runup of long waves approaching a cliff over a variable bathymetry

Long waves approaching a cliff are significantly affected by a variable bathymetry. Wave breaking is observed, and determined by both the bathymetry and nonlinear interactions of the waves with the cliff and other waves. Geometric and kinematic measures are applied to determine a breaking criteria, however there are inconsistencies in both when the wave parameters are close to breaking/non-breaking interface values. Wave crest cliff interaction is discussed in terms of its effect on the phase and fluid velocities. Runup amplification increases with the number of waves in the approaching wavepacket, their amplitude, and the bathymetry slope, but is approximately independent of the wave period. Runup amplifications approaching a factor of 12 are observed for a bathymetry approximating that of the Aran Islands, Ireland. (C) 2017 The Authors. Published by Elsevier B.V. Selection and peer-review under responsibility of IUTAM Symposium on Storm Surge Modelling and Forecasting.