HR: 1340h
AN: H43A-0366    [Abstracts]
TI: Effects of Bedload and Suspended Load on the Separation of Sands and Fines in Mixed Sediments
AU: * Roberts, J D
EM: jdrober@sandia.gov
AF: Sandia National Laboratories, Carlsbad Programs 4100 National Parks highway, Carlsbad, NM 88220 United States
AU: James, S C
EM: scjames@sandia.gov
AF: Sandia National Laboratories, Geohydrology Department P.O. Box 5800, Albuquerque, NM 87185-0735 United States
AU: Jepsen, R A
EM: rajepse@sandia.gov
AF: Sandia National Laboratories, Mechanical Environments P.O. Box 5800, Albuquerque, NM 87185-1135 United States
AB: A high-shear stress straight flume commonly used to measure cohesive sediment erosion rates has been modified to include downstream bedload traps. The modified flume, called ASSET Flume, can then be used not only to measure erosion rates, but also to analyze and quantify the modes of transport. The modified flume was used to study erosion rates of quartz particles ranging in size from 19--1250~$\mu$m in order to validate the design and operation. Natural sediments from three locations were studied using the modified flume. Fine sediments with little or no sand eroded as aggregates. These aggregates maintained their integrity in the flume channel and moved as bedload into the traps. Natural sediments that included high percentage of sand also eroded as aggregates. However, these aggregates quickly fell apart with the extent of their disintegration proportional to the initial sand content. The sand moved as bedload and fell into the traps while fine particles separated from the sand and moved predominately in suspension. The ability to accurately quantify the modes of transport and the properties of the transported material by means of direct measurement is unique. These measurements are extremely important in determining whether dredge material made up of mixed sediments is suitable for near-shore placement and beach replenishment. {\st Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.}
DE: 1815 Erosion and sedimentation
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting