HR: 16:45h
AN: H54A-03    [Abstracts]
TI: Multi-year tracking of sediment sources in a small agricultural watershed using rare earth elements
AU: * Kimoto, A
EM: akimoto@tucson.ars.ag.gov
AF: USDA-ARS Southwest Watershed Research Center, 2000E Allen Rd., Tucson, AZ 85719 United States
AU: Nearing, M
EM: mnearing@tucson.ars.ag.gov
AF: USDA-ARS Southwest Watershed Research Center, 2000E Allen Rd., Tucson, AZ 85719 United States
AU: Shipitalo, M
EM: martin@coshocton.ars.usda.gov
AF: USDA-ARS North Appalachian Experimental Watershed, P.O. Box 488, Coshocton, OH 43812 United States
AU: Polyakov, V
EM: viktor@hawaii.edu
AF: University of Hawaii, Department of Natural Resources and Environmental Management, 1910 East-West Road, Honolulu, HI 96822 United States
AB: Rare earth elements (REEs) were used to monitor sediment source areas in a small agricultural watershed near Coshocton, Ohio, USA. Six morphological elements within the watershed were tagged with different REEs, and sediment yield was collected at the watershed outlet for nearly four years after the tracer application. The REE concentrations in the sediment yield were measured to evaluate the relative contribution of each morphological element to sediment yield from the watershed. The tracer depletion and the tracer enrichment ratio were evaluated to examine the applicability and accuracy of the REE technique for the experimental period. A minimum of approximately 91% of the mass of the applied elements was still available on any individual morphological element at the end of experimental period. The tracer enrichment ratio varied from 0.4 to 2.3 during the experimental period, and it did not significantly decrease as a function of time. The relative contribution of a morphological element was computed as a proportion of sediment yield from a morphological element to sediment yield from the watershed. The relative contribution of the lower channel was significantly increased as a function of the amount of sediment yield for a given storm, while that of the lower backslope was significantly decreased. The relative contribution of the lower channel significantly decreased as a function of cumulative sediment yield, while the contributions of the shoulder and the upper backslope significantly increased. This study showed that the REE technique has a reasonable potential for studying sediment sources for a multi-year period with significant limitations associated with a selective depletion of tracers and a contamination of downslope areas with tagged sediments from upslope areas.
UR: http://www.ars-grin.gov/ars/MidWest/Coshocton/index.htm
DE: 1815 Erosion
DE: 1850 Overland flow
DE: 1862 Sediment transport (4558)
DE: 1872 Time series analysis (3270, 4277, 4475)
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005