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In this paper, large-scale experimental data are presented showing the beach profile morphological evolution induced by four different bi-chromatic wave conditions characterized by very similar energy content between them but varying the modulation period. Important differences were observed in the resultant beach profiles as a function of the wave group periods. Larger variability in the profile evolution is generally observed for larger wave group periods and, more importantly, as the wave group period increases the distance between the generated breaker bar and the shoreline increases. The measured primary wave height to depth ratio () increases with the wave group period, which is consistent with the observed larger wave height at the breaking location. The primary wave 2 breaking location is also observed at increasing distances with respect to the initial shoreline as the wave group period increases. The variation in  with wave group period is related to the selective energy dissipation of the higher primary frequency component (f1) during the wave group shoaling. Broad bandwith conditions (reduced wave group period) lead to larger dissipation of wave heights at the f1 component relative to f2 resulting in a reduction in the wave modulation and primary wave height at the breaking location. Suspended sediment fluxes obtained from collocated velocity and sediment concentration measurements in the surf zone showed a consistently larger contribution of the mean return flow to the suspended sediment fluxes compared with the wave group and primary wave components. The distinct beach profile evolution in terms of bar location is interpreted from an increasing distance of the mean breakpoint location and the location of maximum return flow with respect to the shoreline as the wave group period increases.Keywords: bi-chromatic wave groups, bar morphology, sediment transport, suspended sediment concentration, large scale experiments, morphodynamics. -IntroductionHigh frequency (hf) wave groups and the associated low frequency (lf) waves are natural characteristics of random waves propagating to coastal areas. Wave grouping has important implications in coastal sediment transport and in the evolution of the coastal morphology.Measured sediment transport rates in surf zone conditions suggest a larger influence of mean components and short-scale wind and swell waves in the net cross-shore sediment transport (Ruessink et al., 1998). However, the relative importance of long waves has been showed to increase within the surf zone, as short wave dissipation occurs via wave breaking, and has 3 been reported to dominate the suspended sediment transport in the inner surf zone (Aagaard and Greenwood, 2008).Moreover, beach evolution is the result of sediment transport gradients that may vary at the time-scales of long waves and wave groups. Wave groups also introduce further intermittency into the short-wave scale hydrodynamics (i.e. wave breaking, slow modulation of the water depth and wave height to water depth ratio...

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