Undular Tidal Bores: Basic Theory and Free-Surface Characteristics

The present study examines the free-surface properties of undular tidal bores observed for 1 < F < 1.5-1.8. The analysis is based on some new experimental results together with a reanalysis of both field and laboratory data. The free-surface profiles followed a pattern somehow similar to the sinusoidal and cnoidal wave shapes, although neither captures the fine details of the undulation profiles. The wave properties highlighted some maxima in amplitude and steepness for a Froude number of about 1.3-1.4 corresponding to the apparition of some wave breaking at the first wave crest.