Photographic Observations of Tidal Bores (Mascarets) in France

A tidal bore is a series of waves propagating upstream as the tidal flow turns to rising. It forms during spring tide conditions when the tidal range exceeds 4 to 6 m and the flood tide is confined to a narrow funnelled estuary. The existence is based upon a fragile hydrodynamic balance between the tidal amplitude (marnage), the freshwater river flow conditions and the river channel bathymetry, and it is shown that this balance may be easily disturbed by changes in boundary conditions and freshwater inflow. Although the Seine River no longer has its tidal bore, more than of dozen of estuaries are affected by tidal bores in France alone. Herein the writer aims to share his enthusiasm and passion for tidal bores by documenting several tidal bores in France with photographic observations. More than 65 photographs are presented and documented. This technical report is supported by a digital appendix (Appendix B) containing a slide show movie and two sound records available at the University of Queensland institutional open access repositoryUQeSpace. A glossary of technical terms is available after the list of symbols.