ABSTRACT
In macro-tidal estuaries, a tidal bore may form during spring tide conditions when the flood tide is confined to a narrow channel. The bore is a series of waves propagating upstream as the tidal flow turns to rising (Fig. 1). The occurrence of tidal bores has a significant impact on river mouths and estuarine systems. Bed erosion and scour take place beneath the bore front while suspended matters are carried upwards in the ensuing wave motion. The process contributes to significant sediment transport with deposition in upstream intertidal areas. Tidal bores induce also strong mixing and dispersion in the river mouth, but classical mixing theories do not account for such type of discontinuities. The existence of tidal bores is based upon a fragile hydrodynamic balance which may be easily disturbed by changes in boundary conditions and freshwater inflow (e.g. Chanson 2004a, 2005a).
