HR: 0800h
AN: H51E-0796    [Abstracts]
TI: Fine sediment infiltration into gravel bed: theory and experiments
AU: * Cui, Y
EM: yantao@stillwatersci.com
AF: Stillwater Sciences, 2855 Telegraph Ave., Berkeley, CA 94705, United States
AU: Wooster, J
EM: wooster@stillwatersci.com
AF: Stillwater Sciences, 2855 Telegraph Ave., Berkeley, CA 94705, United States
AU: Dusterhoff, S
EM: dusterhoff@stillwatersci.com
AF: Stillwater Sciences, 2855 Telegraph Ave., Berkeley, CA 94705, United States
AU: Baker, P
EM: pfb@stillwatersci.com
AF: Stillwater Sciences, 2855 Telegraph Ave., Berkeley, CA 94705, United States
AU: Sklar, L
EM: leonard@sfsu.edu
AF: San Francisco State University, Department of Geosciences, San Francisco, CA 94132, United States
AU: Dietrich, W E
EM: bill@eps.berkeley.edu
AF: Univerisity of California, Department of Earth and Planetary Sciences, Berkeley, CA 94720, United States
AB: We derived partial differential equations (PDEs) that describe the process of fine sediment infiltration into coarse sediment deposits based on mass conservation and our intuitive understanding of the physical processes involved. We reasoned that fine sediment trapping efficiency (FSTE), defined as the volumetric fraction of fine sediment trapped in the deposit per unit downward distance traveled, is either independent of fine sediment fraction (FSF) within the deposit or increases monotonically as the FSF increases. Solution to the PDEs under the assumption that FSTE is independent of FSF indicates that the equilibrium FSF decreases exponentially with depth into the deposit following fine sediment infiltration into a deposit initially void of fine sediment. Solutions to the PDEs under the assumption that FSTE is a function of FSF results in non-exponential decay function for fine sediment fraction that decreases faster into the depth compared to the exponential profile under the assumption that FSTE is independent of FSF. We also conducted flume experiments independent of the theoretical analysis to examine fine sediment infiltration into clean coarse sediment deposits. Experimental results illustrate that an exponential decay function with depth into the deposit adequately describes the FSF profile following infiltration, indicating that FSTE is at most weakly dependent on FSF in the deposit. Results from the experiments also provide quantifications to the coefficients within the theory as functions of the grain size distributions of the infiltrating fine sediment and the coarse deposit. Quantitatively comparing the theoretical solution under the assumption that FSTE is independent of FSF with the experimental data indicates that the root-mean-square- error between theoretical prediction and weighted-averaged experimental data is 7.3 percent of the predicted saturated FSF value (i.e., predicted maximum FSF once fine sediment can no longer infiltrates through the near- surface layer to reach the deeper part of the deposit), indicating a good agreement.
UR: http://www.stillwatersci.com/PubUnderReview
DE: 1813 Eco-hydrology
DE: 1825 Geomorphology: fluvial (1625)
DE: 1861 Sedimentation (4863)
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: 2007 Fall Meeting