Coupled sandbar patterns and obliquely incident waves

In double sandbar systems, the alongshore variability in the inner bar oftenresembles that of the outer bar, suggesting that the outer bar acts as a morphologicaltemplate for the inner bar. Earlier observations have indicated that this resemblance, alsotermed “coupling,” may take several forms. Here we apply a nonlinear 2DHmorphodynamic model with time-invariant forcing to show that the angle of waveincidence (Â) is crucial for the alongshore-variable morphodynamic evolution of the innerbar, for a given crescentic outer bar. In contrast to previous modeling efforts ofdouble-barred systems, which mostly used highly idealized boundary conditions, weforce our model with realistic hydrodynamics and bathymetrical data derived from videoobservations at the double-barred Gold Coast, Australia. The results show that for smallangles of wave incidence (Â