Moskalski, S.; Floc'h, F.; Verney, R.; Fromant, G.; Le Dantec, N., and Deschamps, A., 2018. Sedimentary dynamics and decadal-scale changes in the macrotidal Aulne River estuary, Brittany, France.

Studies of macrotidal estuaries have been dominated by large, high-turbidity systems like the Gironde and Severn, but some macrotidal estuaries are different from these systems. The goal of this study was to document the state of hydrosedimentary processes in the macrotidal, low-turbidity Aulne River estuary and, where possible, compare it to a previous study. Study sites from a 1977 study were revisited in 2013. Observations of velocity, salinity, and suspended sediment concentration were analyzed and compared to the 1977 study, with particular attention given to hourly data. The results illustrate the impact of shallowing on hydrosedimentary processes. The estuary is strongly dominated by spring–neap variability and shallowing, with increasing tidal distortion in the landward direction and a turbidity maximum zone created by sediment resuspension. The maximum flooding and ebbing velocity were stronger and tidal velocity distortion was more pronounced than in 1977. The salinity intrusion moved farther landward during low discharge in 2013 than in 1977, but not during average and high discharge. Other hydrosedimentary processes remained consistent with the previous study. This study also illustrates potential problems that can occur when attempting to use historical analyses.