Effect of Organic Materials on Bulk Density and Erodibility of Fine Sediment Beds

摘要

Despite more than a century of research on sediment processes, there still exist a number of knowledge gaps regarding key sediment processes. Research is needed on the description and analysis of sediment processes. The objective of research on sediment processes is to provide new knowledge of cohesive sediment erosion processes and release of associated nutrients plus development of improved algorithms for erosion/release rate as a function of bulk density, organic content, and other easily measured parameters. Most of the fine sediments occurring in natural environments such as lakes, wetlands and estuaries contain organic material. The type and amount of organic contents are site-specific and may vary to a great extent. The bulk density and erosion rates of fine sediment beds are known to be significantly affected by the organic contents; however, their influence has not been adequately quantified. Bulk density and erodibility are the properties of cohesive sediments that are affected by the presence of organic substances. It is essential to know bulk density to be able to predict the erosion rates of cohesive sediment beds because shear strength is often related to bed density of cohesive sediments. The purpose of this report is to present results of laboratory measurements conducted at CHL on the influence of organic contents on bed density and erodibility of cohesive sediments at various project sites. Background information on the basic properties of fine sediments, their characterization, and fine sediment beds is also given.