Settling velocity of sediments from reservoirs, laboratory measurements and numerical modeling

The assessment of the settling velocity of cohesive sediments is a major issue when dealing with reservoir sediment management. Laboratory measurements using several devices have been performed. Traditional measurements with an Andreasen pipette or a weighting device are compared with the ones obtained with an innovative device, based on an optical settling column (SCAF). Sediments were sampled in nine French reservoirs exhibiting contrasted sediment characteristics (grain-size, organic content, mineralogy.). The dependence of settling velocity on concentration is evaluated for a wide range of concentrations. Measurement results are analyzed, discussed and assimilated in a 3D numerical model to assess the sensitivity of simulations to settling velocity.