THE GENERATION OF ROGUE WAVES FROM SURF ZONE INFRAGRAVITY MOTIONS PENETRATING A BAR-BUILT SHALLOW ESTUARY

Rogue waves have been the subject of intensive research and scientific debates over the last 20 years. In oceanographic contexts, they are defined as infrequent large waves (with heights more than 2 times the significant wave height of the carrier field) suddenly appearing among a group of smaller wind generated waves (Haver and Anderson, 2000). They have been seldom observed in nature, yet causing significant damage and casualties (Kharif and Pelinovsky, 2003). In the present contribution, we present field measurements of infragravity waves penetrating into a shallow bar-built estuary located in the Pacific border of Central Chile (34.48°S, 72.00°W). We show that the shallow and narrow canal connecting the river to the sea acts as a natural low-pass filter for swell frequencies, as it has been previously documented (Willliams et al., 2016; McSweeney et al., 2020). The quasi-periodic entrance of infragravity motions into the estuary evolve over a shallow bathymetry as highly nonlinear long-waves that fission into solitonic wave trains. The statistical analysis of the measured wave heights show that the resulting field is of strongly non- Gaussian nature, with a frequent appearance of rogue waves.