In situ Particle Size and Volume Concentration of Suspended Sediment in Seomjin River Estuary, Determined by an Optical Instrument, 'LISST-100'

摘要

In situ particle size and volume concentration of suspended sediment was measured at the mouth of Seomjin River Estuary in February 2001, using an optical instrument, 'LISST-100'. Time variation of in situ particle size and concentration shows: (1) during ebb tide, Seomjin River supplies relatively fine-grained particles with less-fluctuated, compared to during flood tide, and well-behaved concentrations following the tidal cycle; and (2) during flood tide, relatively coarse-grained particles with highly variable in size distribution and concentration flow upstream from Kwangyang Bay. This explains a poor correlation (r"=0.10) between sediment concentration and beam attenuation coefficient during flood and a high degree of correlation (r2=0.80) during ebb tide. Relatively fine grained and well defined, monotonous size distribution may promote the correlation between concentration and beam attenuation coefficient due to optical homogeneity of particles during ebb tide. Abundance of large aggregateswith time-varying size and shape distributions may be mainly responsible for variations in optical properties of the sediment during flood tide, and thus may confound the relationship between the two variables. The difference in particle sizes and shapesbetween flood and ebb tides can also be observed on SEM images.