Experimental Study of Salinity Effects on Time Variation of Suspended cohesive Sediment Concentration Using an Annular Flume

Behaviors of cohesive sediments are influenced by many physicochemical properties. In this study in order to investigate salinity effects on time variation of suspended cohesive sediment concentration some experimental tests were conducted in an annular flume. Sediment samples were composed 63.2% of clay, 36.1 %of silt and 0.7% of sand. Velocity and shear stress profiles were measured by ADV velocimeter. Duration for each experiment was 360 minutes and the equilibrium condition was occurred in ranging of 40 min to 2 hours, for different tests. The results showed that different level of salinity has similar effect on flocculation of cohesive sediments. In a higher value of shear stress (i.e. 0.593 N/m2) the salinity hadn’t significant effect on reaching of suspended cohesive sediment to an equilibrium condition, but in a lower value of shear stress (i.e. 0.299 N/m2) the salinity had more significant effect. The results also showed that in flocculation processes of cohesive sediments shear stress was an effective parameter comparing to salinity.