Hydrogéomorphologie et inondabilité

Abstract

Hydrogeo-morphological mapping is used in France to delimit river flood areas. Several thousands of kilometers of watercourse have thus been analysed then mapped, due to the flood hazard prevention policy urged by the Equipment and Environment ministries since the Barnier law (1995). The problematic of flood hazard leads to observe familiar functional floodplain objects with a point of view slightly different from those generally admitted in fluvial dynamics. Interest in microtopog-raphy and its variations thus allows to distinguish up to four beds in a watercourse. In particular, an intermediate flow channel can be distinguished depending on the order and zone of the watercourse. The inundability problematic also oblige to be particularly careful with the external limit of the flood area. Currently under development, it already produced new results with the description of exceptional high water beds in some watercourses. Finally, the need for precise knowledge of hazard characteristics, such as water height and speed, have led to the development of the integrated method, based on the hydroge-omorphological discharge concept, whose first experimentations are promising.