SUSPENDED SEDIMENT CONCENTRATIONS IN SHALLOW SEA: COMPARATIVE STUDY OF METHODS

Various methods were used to measure the suspended sediment concentrations (SSCs) in the Jiulong Estuary in March, 2010 and in the North Branch of Yangtze Estuary in February, 2011. The synchronous acoustics and optical data including OBS, LISST-100X, ADCP, ADP and ADV were obtained by profiling and seabed tripod measurements. During these surveys, water samples were collected from the water columns form the sea surface down to the bottom, and then the SSC was retrieved by filtration in the lab.Distinctions were discerned among the above methods. Firstly, the seawater filtration is a benchmark method. Secondly, SSCs could be successfully and accurately estimated from acoustic and optical instruments installed at the same height above the seabed, with small measurement errors. Hence, they can be replaced each other, as a case of complementary measurement. Finally, the settling method may overestimate the SSCs, comparing to the filtration method due to the saline substance remained in the sediments. Thus, in order to estimate better SSCs, a suitable method should be selected according to the study purpose and local SSC background.