Non-destructive Image Analysis to Determine Suspended Sediment Size Distribution Characteristics under Varying Flow Conditions, Cazenovia Creek, Ny

Recent studies suggest that suspended sediment in rivers may move predominantly as floes rather than as individual (discrete) particles. Research on flocculation has been facilitated by improved analytical technologies, including image analysis. Because image analysis is a relatively new analytical approach, there is limited information on quality assurance/quality control (QAlQC) procedures. Non-destructive image analysis was used to determine si;:.e distribution characteristics of suspended sediment samples collected from a site 011 Ca;:.enovia Creek, NY, during storm and non-storm events. An important focus of the study was refinement of QAIQC procedures. Samples could be refrigerated for up to 22 days without significant change in si;:.e distribution. Imaging approximately 1,000 particles appears optimum in providing a reliable size distribution and minimizing analytical time. The Pearson Type VI probability distribution typically provided the best fit for the flocculated sediment, while the Extreme Value Type I was best for the primary particle size distributions and the lognormal was best for watershed soils (i.e. source material). Differences between the flocculated size distribution, primary particle size distribution, and soil size distributions may be related to hydraulic sorting and the flocculation process. There was relatively little difference in the flocculated size characteristics of the event and nOIl-el'ent samples and the suspended sediment samples from Cazenovia Creek were not as highly flocculated as samples collected in other rivers. Previous studies have shown environmental factors such as total bacteria, dissolved organic carbon content, and suspended sediment conce1ltration, were related to floc size characteristics, but this typically was not the case for Cazenovia Creek. Ca::.enovia Creek is located in a highlands region and even during non-events the flow is very turbulent. The most important factor governing floc size characteristics for the creek therefore seems to be flow hydraulics. INTRODUCTION aI., 1989; Urbain et aI., 1993; Li and Ganczarezyk, 1986), but it is only within the past decade that flocculation has been examined as a dominant mode The literature is replete on sediment of transport in freshwater fluvial systems (e.g. flocculation characteristics in marine and urban Ongley et aI., 1992; Droppo and angley, 1992; sewage systems (e.g. Kranck, 1984; Muschenheim et Walling and Woodward, 1993; Droppo and angley,