ABSTRACT
ABSTRACT: When a river mouth has a flat converging shape and when the tidal range exceeds 6 to 9 m, the river may experience a tidal bore. A tidal bore is basically a positive surge propagating upstream as the tidal flow turns to rising. The occurrence of a bore has a significant impact on estuarine systems. Bed erosion and scour take place beneath the bore front while suspended matters may be carried upwards in the following wave motion. Analogies between hydraulic jumps and positive surges suggest that mixing coefficients are much greater than in estuary flows. Tidal bores impact also significantly on eco-systems. The existence of tidal bores relies upon a fragile hydrodynamic balance, which may be easily disturbed by changes in boundary conditions and freshwater inflows.
