Relationship between Acoustic Backscatter Strength and Suspended Sediment Concentration using a 6 MHz Nortek Vector Velocimeter

This paper presents a laboratory study that evaluates the relationship between suspended sediment concentration (SSC) and the acoustic backscatter strength recorded by a Nortek Vector velocimeter for different natural and commercial sediments. Tests were conducted in a tank using kaolinite and three other types of natural mud taken from the Houston Ship Channel. SSCs ranged from 0.001 to 7 g/l for kaolinite and 3.5 g/l for natural sediments. Results show two regions of response in the relationship between the acoustic return and the SSC. The first region was for concentrations less than 3.2 g/l. In this region, the strength of the return signal is linearly related to the logarithm of concentration with a constant positive slope. Above this concentration, the strength of the acoustic return decreases with increased concentration. The study examines the difference in these basic trends among the different sediment types.