Hétérogénéité spatiale et événementielle des vitesses de chute des sédiments décantés dans un bassin de retenue d'eau pluviale

The Django Reinhardt sedimentation basin (in Chassieu, France) provided the basis
for an experimental monitoring campaign to better understand and model
sedimentation behaviour in full-scale sedimentation systems. Twelve sediment traps
placed at the base of the sediment basin permitted solids settled during storm events
to be sampled for both settling velocity (according to the French VICAS laboratoryanalysis protocol) and heavy metal concentrations. The first three monitoring
campaigns demonstrated significant spatial variability in the sediment settling velocity,
within a given storm event. Temporal variability between events was also found to be
substantial. Uncertainties in the estimated setting velocities were found to be
insignificant (typically less than 7%). Importantly, the concentration of heavy metals
was observed to increase with increasing sediment settling velocity.