Estimating remaining concentration-percentages of resuspended sediments via a non-local particle model for flocculation

Abstract

Maritime works often require sediment handling activities such as dredging and disposal, to maintain harbors and channels, nourish sandy beaches as well as to carefully remove and relocate contaminated materials from the bottom of estuarine and coastal areas. Such operations often lead to an increase in the concentration of suspended sediments in water columns, which in turn causes adverse effects on water quality and aquatic lives. Minimizing these detrimental impacts require designing such maritime works with care, by paying attention to the geometry of areas affected by the sediment resuspension. Numerical modeling has been recognized as a valuable tool to help designers and contractors to optimize such sediment handling works. In obtaining such, one of the most challenging aspects to be tackled is the estimation of the settling velocity of the fine-grained mixture that results from sediment resuspension. These settling velocities are affected by a phenomenon known as flocculation. In this paper, the concept of non-local interacting particles was used to formulate a one-dimensional model for the flocculation phenomenon. Also, a (deterministic) particle transport equation was formulated to reproduce the settling behavior of suspended sediments in a settling column. The proposed model was solved numerically. The simulation results provide an understanding of the mechanisms of flocculation and highlight how flocculation influences floccule-settling velocities and concentration percentages of sediments that remain in suspension.

Keywords:

• sediment transport model
• floccule-settling velocity
• deterministic particle method
• non-local interaction
• settling-column tests