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• 1. [Article] Particle Trapping in Stratified Estuaries - Definition of a Parameter Space

  Estuarine turbidity maxima (ETM) retain suspended particulate matter (SPM) through advection, settling, aggregation and non-linearities in bed processes. This contribution defines for the first time a ...

  Citation × Citation Citation Abstract Copy Title: Particle Trapping in Stratified Estuaries - Definition of a Parameter Space Author: Jay, David A., Orton, Philip M., Chisholm, Thomas A., Wilson, Douglas J., Fain, Annika M., McGinity, John Year: 2003 Estuarine turbidity maxima (ETM) retain suspended particulate matter (SPM) through advection, settling, aggregation and non-linearities in bed processes. This contribution defines for the first time a parameter space descriptive of ETM water-column particle trapping processes through a scaling analysis of the local and integral SPM balances. In the absence of long-term deposition, there are five primary parameters for the large particles or aggregates that are typically trapped. Rouse number P, the ratio of settling velocity WS of the SPM relative to the shear velocity U*, describes the material trapped in the ETM in terms of the local vertical balance between vertical mixing and aggregate settling. Advection number A= P ΔU/UT scales the landward transport of SPM by tidal and mean flow processes in terms of flood-ebb velocity difference (ΔU) and maximum tidal current (UT). Supply number SR = P UR/UT defines SPM supply and removal (UR is river flow). Changes in the estuarine inventory of SPM are described in terms of a Trapping Efficiency E, a ratio of peak ETM concentration to fluvial or marine supply concentration. The effects of aggregation in the integral dynamic balance are quantified by a Floc number F that describes the tendency of aggregates to form through shear-driven collisions. This study uses observations from two strongly advective systems (the Columbia and Fraser Rivers) plus literature values from 13 other estuaries to illustrate the applicability of the above scaling. The primary question investigated is the relationship of trapping efficiency E and Floc number F to other parameters, especially river flow (expressed in terms of supply number SR). The strongest SPM trapping (high E) occurs in mid-ETM, where A ~0. The extreme high flows observed in the Fraser River estuary show how ETM trapping becomes ineffective as the estuary length contracts to one tidal excursion or less (limit of high SR). Use of data from all 15 estuaries shows that there is a strong trend toward more efficient trapping for low SR. E and F are positively correlated, so that aggregation becomes more prominent in systems with weak to moderate river flow. Examination of tidal monthly and seasonal particle properties at four closely-spaced moorings in the Columbia emphasize the importance of strong ETM gradients – particle properties are diverse even when the hydrodynamic regime is apparently similar. Finally, scaling variables and data are combined to express ETM properties in terms of U*, UR and UT.. Title: Particle Trapping in Stratified Estuaries - Definition of a Parameter Space Author: Jay, David A., Orton, Philip M., Chisholm, Thomas A., Wilson, Douglas J., Fain, Annika M., McGinity, John Year: 2003 Estuarine turbidity maxima (ETM) retain suspended particulate matter (SPM) through advection, settling, aggregation and non-linearities in bed processes. This contribution defines for the first time a parameter space descriptive of ETM water-column particle trapping processes through a scaling analysis of the local and integral SPM balances. In the absence of long-term deposition, there are five primary parameters for the large particles or aggregates that are typically trapped. Rouse number P, the ratio of settling velocity WS of the SPM relative to the shear velocity U*, describes the material trapped in the ETM in terms of the local vertical balance between vertical mixing and aggregate settling. Advection number A= P ΔU/UT scales the landward transport of SPM by tidal and mean flow processes in terms of flood-ebb velocity difference (ΔU) and maximum tidal current (UT). Supply number SR = P UR/UT defines SPM supply and removal (UR is river flow). Changes in the estuarine inventory of SPM are described in terms of a Trapping Efficiency E, a ratio of peak ETM concentration to fluvial or marine supply concentration. The effects of aggregation in the integral dynamic balance are quantified by a Floc number F that describes the tendency of aggregates to form through shear-driven collisions. This study uses observations from two strongly advective systems (the Columbia and Fraser Rivers) plus literature values from 13 other estuaries to illustrate the applicability of the above scaling. The primary question investigated is the relationship of trapping efficiency E and Floc number F to other parameters, especially river flow (expressed in terms of supply number SR). The strongest SPM trapping (high E) occurs in mid-ETM, where A ~0. The extreme high flows observed in the Fraser River estuary show how ETM trapping becomes ineffective as the estuary length contracts to one tidal excursion or less (limit of high SR). Use of data from all 15 estuaries shows that there is a strong trend toward more efficient trapping for low SR. E and F are positively correlated, so that aggregation becomes more prominent in systems with weak to moderate river flow. Examination of tidal monthly and seasonal particle properties at four closely-spaced moorings in the Columbia emphasize the importance of strong ETM gradients – particle properties are diverse even when the hydrodynamic regime is apparently similar. Finally, scaling variables and data are combined to express ETM properties in terms of U*, UR and UT.. Close

• 2. [Article] Impacts of Columbia River Discharge on Salmonid Habitat: 1. A Nonstationary Fluvial Tide Model

  This is the first part of a two-part investigation that applies nonstationary time series analysis methods and the St. Venant equations to the problem of understanding juvenile salmonid access to favorable ...

  Citation × Citation Citation Abstract Copy Title: Impacts of Columbia River Discharge on Salmonid Habitat: 1. A Nonstationary Fluvial Tide Model Author: Jay, David A., Kukulka, Tobias Year: 2003 This is the first part of a two-part investigation that applies nonstationary time series analysis methods and the St. Venant equations to the problem of understanding juvenile salmonid access to favorable shallow-water habitat in a tidal river. Habitat access is a function of river stage, tidal range, and the distribution of bed elevation. Part 1 models nonstationary tidal properties: species amplitudes and phases and tidal range. Part 2 models low-frequency river stage in the Lower Columbia River and reconstructs historical water levels, using the tidal model from part 1. To incorporate the nonstationary frictional effects of variable river discharge into the tidal model, we decompose the tidal wave into tidal species and calculate daily tidal range. Our one-dimensional tidal model is based on analytic wave solutions to the linearized St. Venant equation and uses six coefficients per tidal species to represent the upstream evolution of the frictionally damped tidal wave. The form of the coefficients is derived from the St. Venant equations, but their values are determined objectively from the data. About 50 station-years of surface elevation data collected (1981-2000) below Bonneville Dam (235 km from the ocean) were processed with a wavelet filter bank to retrieve time series of tidal species properties. A min-max filter was used to estimate daily tidal range. Tidal range, diurnal, and semidiurnal amplitudes were predicted with mean root mean square errorsmm, which is significantly more accurate than predictions obtained from harmonic analysis. Thus despite the compact form of our solution, we model nonstationary fluvial tidal properties with a high level of accuracy. Title: Impacts of Columbia River Discharge on Salmonid Habitat: 1. A Nonstationary Fluvial Tide Model Author: Jay, David A., Kukulka, Tobias Year: 2003 This is the first part of a two-part investigation that applies nonstationary time series analysis methods and the St. Venant equations to the problem of understanding juvenile salmonid access to favorable shallow-water habitat in a tidal river. Habitat access is a function of river stage, tidal range, and the distribution of bed elevation. Part 1 models nonstationary tidal properties: species amplitudes and phases and tidal range. Part 2 models low-frequency river stage in the Lower Columbia River and reconstructs historical water levels, using the tidal model from part 1. To incorporate the nonstationary frictional effects of variable river discharge into the tidal model, we decompose the tidal wave into tidal species and calculate daily tidal range. Our one-dimensional tidal model is based on analytic wave solutions to the linearized St. Venant equation and uses six coefficients per tidal species to represent the upstream evolution of the frictionally damped tidal wave. The form of the coefficients is derived from the St. Venant equations, but their values are determined objectively from the data. About 50 station-years of surface elevation data collected (1981-2000) below Bonneville Dam (235 km from the ocean) were processed with a wavelet filter bank to retrieve time series of tidal species properties. A min-max filter was used to estimate daily tidal range. Tidal range, diurnal, and semidiurnal amplitudes were predicted with mean root mean square errorsmm, which is significantly more accurate than predictions obtained from harmonic analysis. Thus despite the compact form of our solution, we model nonstationary fluvial tidal properties with a high level of accuracy. Close

• 3. [Article] Effects of Ambient Velocity Shear on Nonlinear Internal Wave Associated Mixing at the Columbia River Plume Front

  Large-amplitude nonlinear internal waves (NLIWs) are frequently observed propagating away from Columbia River tidal plume fronts. They are generated because of the deceleration of the frontal bulge. During ...

  Citation × Citation Citation Abstract Copy Title: Effects of Ambient Velocity Shear on Nonlinear Internal Wave Associated Mixing at the Columbia River Plume Front Author: Pan, Jiayi, Jay, David A. Year: 2008 Large-amplitude nonlinear internal waves (NLIWs) are frequently observed propagating away from Columbia River tidal plume fronts. They are generated because of the deceleration of the frontal bulge. During the River Influences on Shelf Ecosystems project cruises, the velocity, density structure and acoustic backscatter of the plume fronts and frontal NLIWs were observed using a towed vehicle, vessel-mounted instrumentation, and a vessel X band radar. These observations indicate that in the presence of strong ambient velocity shear, the NLIWs with maximum amplitudes occur well below the density interface and at a depth deeper than in the absence of shear. This deepening of the NLIW shear is associated with intensified vertical mixing below the interface. This is consistent with a dynamic analysis of NLIWs under the influence of sheared ambient flow, obtained from a high-order KdV model. There are two mechanisms responsible for the vertical turbulent mixing intensification. The nonlinear interaction between ambient shear and the NLIWs increases total velocity shear and causes the gradient Richardson number Rig to decrease below a critical value in certain depth ranges. Also, because of the presence of the ambient shear, the maximum NLIW velocity shear occurs at a depth below the density interface where there is less stratification. Title: Effects of Ambient Velocity Shear on Nonlinear Internal Wave Associated Mixing at the Columbia River Plume Front Author: Pan, Jiayi, Jay, David A. Year: 2008 Large-amplitude nonlinear internal waves (NLIWs) are frequently observed propagating away from Columbia River tidal plume fronts. They are generated because of the deceleration of the frontal bulge. During the River Influences on Shelf Ecosystems project cruises, the velocity, density structure and acoustic backscatter of the plume fronts and frontal NLIWs were observed using a towed vehicle, vessel-mounted instrumentation, and a vessel X band radar. These observations indicate that in the presence of strong ambient velocity shear, the NLIWs with maximum amplitudes occur well below the density interface and at a depth deeper than in the absence of shear. This deepening of the NLIW shear is associated with intensified vertical mixing below the interface. This is consistent with a dynamic analysis of NLIWs under the influence of sheared ambient flow, obtained from a high-order KdV model. There are two mechanisms responsible for the vertical turbulent mixing intensification. The nonlinear interaction between ambient shear and the NLIWs increases total velocity shear and causes the gradient Richardson number Rig to decrease below a critical value in certain depth ranges. Also, because of the presence of the ambient shear, the maximum NLIW velocity shear occurs at a depth below the density interface where there is less stratification. Close