It is well known that colloidal particles, such as clay minerals, which enter into the sea from river inflow, change their sedimentation velocity due to the interaction with other particles as aggregation and disaggregating. These mechanisms are comparable to that of the scavenging effect used for the sedimentation/diffusion analysis of radioactive materials. So, in this research, concentration analysis was conducted on the basis of a soil discharge scenario with considerations given to flow, mixing, scavenging. Using this sedimentation-diffusion model it is possible to predict the amount of clay particles, which reach the seabed near shore or river mouth based on aggregation/disaggregating interactions.