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Modélisation de propagation d’écoulement entre lits mineur et majeur sur les fleuves Sénégal et Niger

Bader, Jean-Claude, Belaud, Gilles, Lamagat, Jean-Pierre, Ferret, Thibaud, Vauchel, Philippe
Hydrological sciences journal 2017 v.62 no.3 pp. 447-466
floodplains, floods, lakes, models, rivers, stream channels, topography, Niger, Senegal
RÉSUMÉ In the Senegal River valley and Niger Inner Delta, the annual floods inundate a wide floodplain consisting of a complex network of lakes and channels, where topographic information needed by standard hydraulic models is difficult to obtain. To represent the flood propagation between mainstream and floodplain, we use a model designed for flood propagation in river mainstreams with flat bed and large overflow and without topographic data. Depending on the water level in the riverbed, the model calibrated on the levels observed at two stations gives the level in the floodplains and propagation time between stations. Several cases are tested for various types of hydraulic connections between mainstream and floodplain. The model could correctly reproduce the flood rise and fall in the floodplain, even for a lake connected by a single channel to the riverbed or in the case of a strong attenuation of the flood between very distant stations.