Abstract

Recent studies have emphasized on the drastic morphodynamic evolution of many european urbanized estuaries, which have become more turbid during the XXth century because of human-induced deepening and narrowing (Winterwerp et al., 2013; De-Jonge et al., 2014). For some systems, the availability of data has allowed detailed analysis of evolution (Vandenbruwaene et al., 2013), while for some other estuaries, knowledge remains limited. For the latter, it is difficult to elucidate any effect due to climate change, extreme events or human activities. Among them, the Gironde estuary is a macrotidal funnel-shape system, the largest estuary of Western Europe, and characterized by high levels of turbidity (Figure 1a). Despite numerous investigations on sedimentary processes carried out in this estuary in the past, there is poor knowledge on the evolution of its morphology and tides over the XXth century. Recently, an exhaustive investigation on tidal patterns has started in the Garonne tidal river, where it is known that gravel extraction during the sixties has deeply modified the mean depth of the channel (Jalon-Rojas et al., this issue). In the meantime, there is evidence of a long-term shift of the turbidity maximum in this area, mainly due to a reduction of river flow in the last 40 years (Jalon-Rojas et al., 2015). However, for the main estuarine portion, which represents 80% of the total surface (Figure 1b), morphology evolution and associated physical processes remain underinvestigated.