In situ observations of floc settling velocities in Glacier Bay, Alaska

Hill, Paul S.; Syvitski, James P. M.; Cowan, Ellen A.; Powell, Ross D.

doi:10.1016/s0025-3227(97)00109-6

Cited by 122 publications

(92 citation statements)

References 17 publications

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“…Graf and Cellino [2002] also showed that for experiments with a flat bed, was typically lower than unity. Field determinations of the relation between and the ratio w s =u Ã can be cast in power law relations with a wide range of exponents [e.g., Whitehouse, 1995;Kawanisi and Yokosi, 1997;Hill et al, 1988Hill et al, , 1998Rose and Thorne, 2001]. Our observations in a moving bed, sandy environment, provide field evidence showing can exceed unity significantly.…”

Section: Discussionmentioning

confidence: 73%

“…[39] Although field estimates of the ratio between sediment to momentum diffusivity are scarce, several studies suggest considerable variation around unity [e.g., Hill et al, 1988Hill et al, , 1998Whitehouse, 1995;Amos et al, 2010]. In general, a positive correlation is found between and suspended sediment size, which critically depends on the flow conditions [Nielsen and Teakle, 2004].…”

Section: Discussionmentioning

confidence: 99%

“…It is often assumed that the sediment and momentum diffusivities are equal and independent of depth [van Rijn, 1984]. Experiments in flumes [e.g., Hill et al, 1988Hill et al, , 1998Cellino and Graf, 1999;Graf and Cellino, 2002;Nikora and Goring, 2002;Muste et al, 2005], however, indicate a wide range of variation around ¼ 1, where denotes the ratio of sediment and momentum diffusivities. Nikora and Goring [2002] showed that a strong depth-dependence may exist.…”

Section: Introductionmentioning

confidence: 99%

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Sediment discharge division at two tidally influenced river bifurcations

Sassi

Hoitink

Vermeulen

et al. 2013

Water Resources Research

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[1] We characterize and quantify the sediment discharge division at two tidally influenced river bifurcations in response to mean flow and secondary circulation by employing a boatmounted acoustic Doppler current profiler (ADCP), to survey transects at bifurcating branches during a semidiurnal tidal cycle. The ADCP collecting flow velocity and acoustical backscatter data was used to quantify suspended sediment discharge, adopting a recently introduced calibration procedure. Measured profiles of flow velocity and sediment concentration allowed us to compute spatiotemporal distributions of the shear velocity, the roughness length and the Rouse number. Spatiotemporal distributions of the settling velocity were obtained by combining the Rouse number and shear velocity estimates with in situ measurements from a laser particle size analyzer. Bed-load transport rates were inferred from shear stress estimates. The concentration field shows a direct response to bed shear stress, stressing the alluvial context of the system. The flow in the bifurcation regions is characterized by counter rotating secondary-flow cells, which stretch over the full width and depth of the cross sections in the downstream branches, and persist throughout the entire tidal cycle. The pattern of secondary flow suggests the flow approaching the bifurcation is concentrated in two independent threads. A two-cell structure inhibits the exchange of sediment that would occur in case a single cell would stretch over the full channel width. The division of suspended sediment primarily depends on the upstream transverse profile of the suspended sediment concentration, which is in turn dependent on geometrical factors such as upstream curvature.

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Section: Discussionmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sediment discharge division at two tidally influenced river bifurcations

Sassi

Hoitink

Vermeulen

et al. 2013

Water Resources Research

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“…Thick, gray line is an estimate of the particulate DIC photoproduction AQY, based on a 0.45 ratio of DIC : DOC production in Louisiana (LA) coastal suspended sediments (Estapa and Mayer 2010). Hill et al [1998]) of an aggregate starting at the surface. Thin dashed lines denote 1-h and 4-h time periods over which reaction rates were measured in the present study.…”

Section: Discussionmentioning

confidence: 99%

Rate and apparent quantum yield of photodissolution of sedimentary organic matter

Estapa

Mayer

Boss

2012

Limnology & Oceanography

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We quantified rates of photochemical dissolution (photodissolution) of organic carbon in coastal Louisiana suspended sediments, conducting experiments under well-defined conditions of irradiance and temperature. Optical properties of the suspended sediments were characterized and used in a radiative transfer model to compute irradiances within turbid suspensions. Photodissolution rate increased with temperature (T), with activation energy of 32 6 7 kJ mol 21 , which implicates indirect (non-photochemical) steps in the net reaction. In most samples, dissolved organic carbon (DOC) concentration increased approximately linearly with time over the first 4 h of irradiation under broadband simulated sunlight, after higher rates in the initial hour of irradiation. Four-hour rates ranged from 2.3 mmol DOC m 23 s 21 to 3.2 mmol DOC m 23 s 21 , but showed no relation to sample origin within the study area, organic carbon or reducible iron content, or mass-specific absorption coefficient. First-hour rates were higher-from 3.5 mmol DOC m 23 s 21 to 7.8 mmol DOC m 23 s 21 -and correlated well with sediment reducible iron (itself often associated with organic matter). The spectral apparent quantum yield (AQY) for photodissolution was computed by fitting DOC photoproduction rates under different spectral irradiance distributions to corresponding rates of light absorption by particles. The photodissolution AQY magnitude is similar to most published dissolved-phase AQY spectra for dissolved inorganic carbon photoproduction, which suggests that in turbid coastal waters where particles dominate light absorption, DOC photoproduction from particles exceeds photooxidation of DOC.

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“…With a natural environment similar to the ones studied here, w smin is estimated to be 6 × 10 Ϫ4 m s Ϫ1 (Churchill et al, 1994). From various sea and laboratory experiments (Gibbs, 1985;Mehta, 1989;Fennessy et al, 1994;Syvitsky et al, 1995;Hill et al, 1998;Manning and Dyer, 1999;Stenberg et al, 1999), the PM mean settling velocity value disperses between 10 Ϫ5 and 10 Ϫ3 m s…”

mentioning

confidence: 99%