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• 31. [Article] Factors for Improved Fish Passage Waterway Construction

  Streambeds are important fish passageways in Oregon; they provide for the necessary habitats and spawning cycles of a healthy fish population. Oregon state law requires that hydraulic structures located ...

  Citation × Citation Citation Abstract Copy Title: Factors for Improved Fish Passage Waterway Construction Author: Sillars, David N., Moradkhani, Hamid, Tymvios, Nicholas, Smith, Trevor D. Year: 2011 Streambeds are important fish passageways in Oregon; they provide for the necessary habitats and spawning cycles of a healthy fish population. Oregon state law requires that hydraulic structures located in water properly provide fish passage. Increasingly stringent state and federal regulations apply to these fish passageways, and designers must become more cognizant of conditions over a range of flows to accommodate fish movement and avoid expensive structural failure of these passageways. Fish passage structures are built when roads cross streambeds and may include culverts, or bridges. When these structures are built, the streambeds are re-created using a technique called “roughened channels”. Roughened channels are man-made stream channels utilized for re-creating the hydraulics necessary for adequate stream passage, and this may include new constructions or retrofits of older, inadequate structures. Mixtures of materials are used to construct the bed of roughened channels, ranging from fines such as sand, silt and gravel to coarse elements like cobbles and boulders. Fines are a critical element in limiting permeability of the constructed bed thus keeping stream flow at the surface of the roughened channel during low flow periods. This report discusses work of a research project designed to discover factors that are key to successful long-term implementation of fish passageways, especially focused on the construction process. Areas of inquiry postulated in this study are that failures experienced in actual installations may be due to inadequate range and/or mix of soil and rock material gradation; unexpected water velocity, especially during high flows; inadequate mixing of rock and soil materials during construction; and inadequate compaction of rock and soil materials during construction. This report suggests that several factors may be especially important considerations in fish passage success. These factors are the relationship of downstream slope to structure slope, well-graded fine soil materials in the channel fill (improved by choice of fill source), and frequent site visits. Improving fish passages for cost-efficient fish movement is a priority for government agencies such as Oregon Department of Transportation (ODOT) and Oregon Transportation Research and Education Consortium (OTREC). Title: Factors for Improved Fish Passage Waterway Construction Author: Sillars, David N., Moradkhani, Hamid, Tymvios, Nicholas, Smith, Trevor D. Year: 2011 Streambeds are important fish passageways in Oregon; they provide for the necessary habitats and spawning cycles of a healthy fish population. Oregon state law requires that hydraulic structures located in water properly provide fish passage. Increasingly stringent state and federal regulations apply to these fish passageways, and designers must become more cognizant of conditions over a range of flows to accommodate fish movement and avoid expensive structural failure of these passageways. Fish passage structures are built when roads cross streambeds and may include culverts, or bridges. When these structures are built, the streambeds are re-created using a technique called “roughened channels”. Roughened channels are man-made stream channels utilized for re-creating the hydraulics necessary for adequate stream passage, and this may include new constructions or retrofits of older, inadequate structures. Mixtures of materials are used to construct the bed of roughened channels, ranging from fines such as sand, silt and gravel to coarse elements like cobbles and boulders. Fines are a critical element in limiting permeability of the constructed bed thus keeping stream flow at the surface of the roughened channel during low flow periods. This report discusses work of a research project designed to discover factors that are key to successful long-term implementation of fish passageways, especially focused on the construction process. Areas of inquiry postulated in this study are that failures experienced in actual installations may be due to inadequate range and/or mix of soil and rock material gradation; unexpected water velocity, especially during high flows; inadequate mixing of rock and soil materials during construction; and inadequate compaction of rock and soil materials during construction. This report suggests that several factors may be especially important considerations in fish passage success. These factors are the relationship of downstream slope to structure slope, well-graded fine soil materials in the channel fill (improved by choice of fill source), and frequent site visits. Improving fish passages for cost-efficient fish movement is a priority for government agencies such as Oregon Department of Transportation (ODOT) and Oregon Transportation Research and Education Consortium (OTREC). Close

• 32. [Article] Archival Water-Level Measurements: Recovering Historical Data to Help Design for the Future

  Improving methods of assessing risk and designing structures to withstand extreme events and changing sea levels is a vital component of strategies for reducing risk to coastal resources and assets. An ...

  Citation × Citation Citation Abstract Copy Title: Archival Water-Level Measurements: Recovering Historical Data to Help Design for the Future Author: Talke, Stefan A., Jay, David A. Year: 2017 Improving methods of assessing risk and designing structures to withstand extreme events and changing sea levels is a vital component of strategies for reducing risk to coastal resources and assets. An obvious approach to improving the statistical robustness of risk assessments is to increase the number, time span, and quality of available water-level data sets, and to assess trends and non-stationarity. In this report we discuss efforts to recover, digitize, and analyze hundreds of station-years of lost-and-forgotten tide data and other water-level measurements that extend back to the early 19th century. To date, more than 6,500 station-years of previously lost or forgotten tide data have been identified, of which more than 1,600 station-years have been recovered and more than 550 station-years digitized. An additional 500+ years of once-a-day river-stage measurements in tidal rivers have been recovered and digitized. Approximately 300,000 documents have been recovered. In this report we also demonstrate how data recovery can help engineers better characterize their water-level environment and understand long-term trends, resulting in better risk assessment and ultimately more robust design of new infrastructure and adaptation of existing infrastructure. Long records help improve hazard estimates and can help characterize whether statistics are nonstationarity over climate-relevant time scales. Further, long and more complete records exhibit more natural variability and can be used to validate numerical simulations of historical storms (e.g., the 1893 New York hurricane). Historical tide data can help inform how tidal datums such as High Water and Low Water have changed, can be used to hindcast historical river flow, and provide a much richer view of long-term trends in local sea level. Used with numerical models, historical data help explain how anthropogenic activities have changed tide range and river slope, with the largest effects often observed far inland from the coast. Moreover, numerical models combined with tide data can be used to assess whether local engineering or other long-term changes have influenced storm surge risk. In conclusion, improved assessment of the past can help us better plan for the future. Title: Archival Water-Level Measurements: Recovering Historical Data to Help Design for the Future Author: Talke, Stefan A., Jay, David A. Year: 2017 Improving methods of assessing risk and designing structures to withstand extreme events and changing sea levels is a vital component of strategies for reducing risk to coastal resources and assets. An obvious approach to improving the statistical robustness of risk assessments is to increase the number, time span, and quality of available water-level data sets, and to assess trends and non-stationarity. In this report we discuss efforts to recover, digitize, and analyze hundreds of station-years of lost-and-forgotten tide data and other water-level measurements that extend back to the early 19th century. To date, more than 6,500 station-years of previously lost or forgotten tide data have been identified, of which more than 1,600 station-years have been recovered and more than 550 station-years digitized. An additional 500+ years of once-a-day river-stage measurements in tidal rivers have been recovered and digitized. Approximately 300,000 documents have been recovered. In this report we also demonstrate how data recovery can help engineers better characterize their water-level environment and understand long-term trends, resulting in better risk assessment and ultimately more robust design of new infrastructure and adaptation of existing infrastructure. Long records help improve hazard estimates and can help characterize whether statistics are nonstationarity over climate-relevant time scales. Further, long and more complete records exhibit more natural variability and can be used to validate numerical simulations of historical storms (e.g., the 1893 New York hurricane). Historical tide data can help inform how tidal datums such as High Water and Low Water have changed, can be used to hindcast historical river flow, and provide a much richer view of long-term trends in local sea level. Used with numerical models, historical data help explain how anthropogenic activities have changed tide range and river slope, with the largest effects often observed far inland from the coast. Moreover, numerical models combined with tide data can be used to assess whether local engineering or other long-term changes have influenced storm surge risk. In conclusion, improved assessment of the past can help us better plan for the future. Close

• 33. [Article] Interfacial Mixing in a Highly Stratified Estuary: 2. A "Method of Constrained Differences" Approach for the Determination of the Momentum and Mass Balances and the Energy of Mixing

  This article is Part 2 of a set of papers addressing mixing in a highly stratified estuary. In Part 2, turbulence and mean flow measurements are together used to understand the role of mixing in the overall ...

  Citation × Citation Citation Abstract Copy Title: Interfacial Mixing in a Highly Stratified Estuary: 2. A "Method of Constrained Differences" Approach for the Determination of the Momentum and Mass Balances and the Energy of Mixing Author: Kay, David J., Jay, David A. Year: 2003 This article is Part 2 of a set of papers addressing mixing in a highly stratified estuary. In Part 2, turbulence and mean flow measurements are together used to understand the role of mixing in the overall dynamics of the system. Estimates of the partition of energy dissipation between bed-generated and internal mixing suggest that internal mixing accounts for about two thirds of the total turbulent kinetic energy (TKE) produced in the salt-wedge reach of the Columbia River estuary during the neap-tide, moderate river-flow observation period. This suggests that internal mixing plays a larger role in the energetics of such systems than has previously been recognized. The lack of near-bed mixing on the neap is also likely a major factor in the accumulation of sediment in the estuary on neap tides. Profiles of estimated turbulent kinetic energy (TKE) dissipation were obtained using a new approach, which we call the "method of constrained differences," that allows the calculation of all major terms in the momentum and density balances during ebb mixing events from data obtained by a single vessel. The method of constrained differences uses a local equilibrium turbulence closure and measured velocity and density profiles to determine the density flux divergence necessary for internal consistency in the momentum and mass equations. The calculated mixing rates from the iterative procedure compare favorably with measured dissipation rates, tending to validate both the measurements and the procedure. Although this method involves a constraint of the form of a known or inferred stress at some point in the water column, it has the potential for wide application, especially if point measurements of TKE dissipation rates are available. Title: Interfacial Mixing in a Highly Stratified Estuary: 2. A "Method of Constrained Differences" Approach for the Determination of the Momentum and Mass Balances and the Energy of Mixing Author: Kay, David J., Jay, David A. Year: 2003 This article is Part 2 of a set of papers addressing mixing in a highly stratified estuary. In Part 2, turbulence and mean flow measurements are together used to understand the role of mixing in the overall dynamics of the system. Estimates of the partition of energy dissipation between bed-generated and internal mixing suggest that internal mixing accounts for about two thirds of the total turbulent kinetic energy (TKE) produced in the salt-wedge reach of the Columbia River estuary during the neap-tide, moderate river-flow observation period. This suggests that internal mixing plays a larger role in the energetics of such systems than has previously been recognized. The lack of near-bed mixing on the neap is also likely a major factor in the accumulation of sediment in the estuary on neap tides. Profiles of estimated turbulent kinetic energy (TKE) dissipation were obtained using a new approach, which we call the "method of constrained differences," that allows the calculation of all major terms in the momentum and density balances during ebb mixing events from data obtained by a single vessel. The method of constrained differences uses a local equilibrium turbulence closure and measured velocity and density profiles to determine the density flux divergence necessary for internal consistency in the momentum and mass equations. The calculated mixing rates from the iterative procedure compare favorably with measured dissipation rates, tending to validate both the measurements and the procedure. Although this method involves a constraint of the form of a known or inferred stress at some point in the water column, it has the potential for wide application, especially if point measurements of TKE dissipation rates are available. Close

• 34. [Article] River-Tide Dynamics: Exploration of Nonstationary and Nonlinear Tidal Behavior in the Yangtze River Estuary

  River-tide dynamics remain poorly understood, in part because conventional harmonic analysis (HA) does not cope effectively with nonstationary signals. To explore nonstationary behavior of river tides ...

  Citation × Citation Citation Abstract Copy Title: River-Tide Dynamics: Exploration of Nonstationary and Nonlinear Tidal Behavior in the Yangtze River Estuary Author: Guo, Leicheng, van der Wegen, Mick, Jay, David A., Matte, Pascal, Wang, Zheng Bing, Roelvink, Dano, He, Qing Year: 2015 River-tide dynamics remain poorly understood, in part because conventional harmonic analysis (HA) does not cope effectively with nonstationary signals. To explore nonstationary behavior of river tides and the modulation effects of river discharge, this work analyzes tidal signals in the Yangtze River estuary using both HA in a nonstationary mode and continuous wavelet transforms (CWT). The Yangtze is an excellent natural laboratory to analyze river tides because of its high and variable flow, its length, and the fact that there are do dams or reflecting barriers within the tidal part of the system. Analysis of tidal frequencies by CWT and analysis of subtidal water level and tidal ranges reveal a broad range of subtidal variations over fortnightly, monthly, semiannual, and annual frequencies driven by subtidal variations in friction and by variable river discharges. We employ HA in a nonstationary mode (NSHA) by segregating data within defined flow ranges into separate analyses. NSHA quantifies the decay of the principal tides and the modulation of M4 tide with increasing river discharges. M4 amplitudes decrease far upriver (landward portion of the estuary) and conversely increase close to the ocean as river discharge increases. The fortnightly frequencies reach an amplitude maximum upriver of that for over tide frequencies, due to the longer wavelength of the fortnightly constituents. These methods and findings should be applicable to large tidal rivers globally and have broad implications regarding management of navigation channels and ecosystems in tidal rivers. Title: River-Tide Dynamics: Exploration of Nonstationary and Nonlinear Tidal Behavior in the Yangtze River Estuary Author: Guo, Leicheng, van der Wegen, Mick, Jay, David A., Matte, Pascal, Wang, Zheng Bing, Roelvink, Dano, He, Qing Year: 2015 River-tide dynamics remain poorly understood, in part because conventional harmonic analysis (HA) does not cope effectively with nonstationary signals. To explore nonstationary behavior of river tides and the modulation effects of river discharge, this work analyzes tidal signals in the Yangtze River estuary using both HA in a nonstationary mode and continuous wavelet transforms (CWT). The Yangtze is an excellent natural laboratory to analyze river tides because of its high and variable flow, its length, and the fact that there are do dams or reflecting barriers within the tidal part of the system. Analysis of tidal frequencies by CWT and analysis of subtidal water level and tidal ranges reveal a broad range of subtidal variations over fortnightly, monthly, semiannual, and annual frequencies driven by subtidal variations in friction and by variable river discharges. We employ HA in a nonstationary mode (NSHA) by segregating data within defined flow ranges into separate analyses. NSHA quantifies the decay of the principal tides and the modulation of M4 tide with increasing river discharges. M4 amplitudes decrease far upriver (landward portion of the estuary) and conversely increase close to the ocean as river discharge increases. The fortnightly frequencies reach an amplitude maximum upriver of that for over tide frequencies, due to the longer wavelength of the fortnightly constituents. These methods and findings should be applicable to large tidal rivers globally and have broad implications regarding management of navigation channels and ecosystems in tidal rivers. Close

• 35. [Article] Residual Circulation in Shallow Estuaries 1. Highly Stratified, Narrow Estuaries

  Long-wave theory and simple turbulence closures have been used to show that three distinct types of circulation (highly stratified, weakly stratified, and partially mixed) arise in narrow, shallow estuaries ...

  Citation × Citation Citation Abstract Copy Title: Residual Circulation in Shallow Estuaries 1. Highly Stratified, Narrow Estuaries Author: Jay, David A., Smith, J. Dungan Year: 1990 Long-wave theory and simple turbulence closures have been used to show that three distinct types of circulation (highly stratified, weakly stratified, and partially mixed) arise in narrow, shallow estuaries from the finite amplitude of the tide and the interaction of stratification with vertical mixing. Each type has a different dominant process causing the vertical exchange of salt and fresh water on the flood, and each gives rise to a characteristic residual circulation. The tidal circulation in highly stratified shallow estuaries, described herein, is the result of a finite amplitude internal motion driven by the barotropic tide; shear instabilities at the interface are the major vertical exchange mechanism. The residual circulation is caused primarily by ebb-flood asymmetry in interface position and thickness. A model based on our theoretical analysis shows that the interface thickness on flood is much less than the depth of flow up to a critical tidal amplitude at which the two-layer flow is destroyed, and correctly predicts the tidal amplitude of the neap-spring transition in the Columbia River Estuary. Tidal frequency internal wave motion is not found in weakly stratified and partially mixed estuaries. Because of the reduced tidal shear, shear instabilities are weak or absent, and the residual circulation assumes a very different character, as described in part 2. Title: Residual Circulation in Shallow Estuaries 1. Highly Stratified, Narrow Estuaries Author: Jay, David A., Smith, J. Dungan Year: 1990 Long-wave theory and simple turbulence closures have been used to show that three distinct types of circulation (highly stratified, weakly stratified, and partially mixed) arise in narrow, shallow estuaries from the finite amplitude of the tide and the interaction of stratification with vertical mixing. Each type has a different dominant process causing the vertical exchange of salt and fresh water on the flood, and each gives rise to a characteristic residual circulation. The tidal circulation in highly stratified shallow estuaries, described herein, is the result of a finite amplitude internal motion driven by the barotropic tide; shear instabilities at the interface are the major vertical exchange mechanism. The residual circulation is caused primarily by ebb-flood asymmetry in interface position and thickness. A model based on our theoretical analysis shows that the interface thickness on flood is much less than the depth of flow up to a critical tidal amplitude at which the two-layer flow is destroyed, and correctly predicts the tidal amplitude of the neap-spring transition in the Columbia River Estuary. Tidal frequency internal wave motion is not found in weakly stratified and partially mixed estuaries. Because of the reduced tidal shear, shear instabilities are weak or absent, and the residual circulation assumes a very different character, as described in part 2. Close

• 36. [Article] Daily Discharge Forecasting Using Least Square Support Vector Regression and Regression Tree

  Prediction of river flow is one of the main issues in the field of water resources management. Because of the complexity of the rainfall-runoff process, data-driven methods have gained increased importance. ...

  Citation × Citation Citation Abstract Copy Title: Daily Discharge Forecasting Using Least Square Support Vector Regression and Regression Tree Author: Sahraei, Shahram, Andalani, Saeed Zare, Zakermoshfegh, Mohammad, Sisakht, Babak Nikeghbal, Talebbeydokhti, Nasser, Moradkhani, Hamid Year: 2015 Prediction of river flow is one of the main issues in the field of water resources management. Because of the complexity of the rainfall-runoff process, data-driven methods have gained increased importance. In the current study, two newly developed models called Least Square Support Vector Regression (LSSVR) and Regression Tree (RT) are used. The LSSVR model is based on the constrained optimization method and applies structural risk minimization in order to yield a general optimized result. Also in the RT, data movement is based on laws discovered in the tree. Both models have been applied to the data in the Kashkan watershed. Variables include (a) recorded precipitation values in the Kashkan watershed stations, and (b) outlet discharge values of one and two previous days. Present discharge is considered as output of the two models. Following that, a sensitivity analysis has been carried out on the input features and less important features has been diminished so that both models have provided better prediction on the data. The final results of both models have been compared. It was found that the LSSVR model has better performance. Finally, the results present these models as a suitable models in river flow forecasting. Title: Daily Discharge Forecasting Using Least Square Support Vector Regression and Regression Tree Author: Sahraei, Shahram, Andalani, Saeed Zare, Zakermoshfegh, Mohammad, Sisakht, Babak Nikeghbal, Talebbeydokhti, Nasser, Moradkhani, Hamid Year: 2015 Prediction of river flow is one of the main issues in the field of water resources management. Because of the complexity of the rainfall-runoff process, data-driven methods have gained increased importance. In the current study, two newly developed models called Least Square Support Vector Regression (LSSVR) and Regression Tree (RT) are used. The LSSVR model is based on the constrained optimization method and applies structural risk minimization in order to yield a general optimized result. Also in the RT, data movement is based on laws discovered in the tree. Both models have been applied to the data in the Kashkan watershed. Variables include (a) recorded precipitation values in the Kashkan watershed stations, and (b) outlet discharge values of one and two previous days. Present discharge is considered as output of the two models. Following that, a sensitivity analysis has been carried out on the input features and less important features has been diminished so that both models have provided better prediction on the data. The final results of both models have been compared. It was found that the LSSVR model has better performance. Finally, the results present these models as a suitable models in river flow forecasting. Close

• 37. [Article] Maintaining Safe, Efficient and Sustainable Intermodal Transport Through the Port of Portland

  About $15 billion of freight passes annually through the Lower Columbia River (LCR) navigation channel to reach Portland and Vancouver, where most of it connects with land transport. This commerce plays ...

  Citation × Citation Citation Abstract Copy Title: Maintaining Safe, Efficient and Sustainable Intermodal Transport Through the Port of Portland Author: Jay, David A., Pan, Jiayi Year: 2011 About $15 billion of freight passes annually through the Lower Columbia River (LCR) navigation channel to reach Portland and Vancouver, where most of it connects with land transport. This commerce plays a vital role in sustaining the regional economy and connecting Oregon to the global economy. The timely connection of truck and rail transport with vessels is vital, especially for export traffic. This link is susceptible to disruption if water depths in the navigation channel are shallower than expected, leading to delays and/or draft limitations. Moreover, ship drafts have increased in recent decades, 25% of the vessels calling in the river sail with a draft close to the channel depth at low water, and these carry roughly 70% of the cargo. A large vessel may have as little as 0.6 m bed clearance when it passes through a low-tide point in the river, which each vessel in transit must do. Thus, prediction and real-time communication of water level to vessels is vital to safety as well as efficiency. This has been implemented through the LOADMAX system, consisting of telemetered water-level gauges and a forecast model. Moreover, the dilemma has been made more critical by changes in the river – low water levels in the river channel between Wauna and Vancouver have decreased 0.3-1.2 m since 1940. The rate of decrease depends on location and riverflow, but appears to have accelerated in the last decade. The reasons for this decrease are not understood. For perspective, an ongoing 0.9 m channel deepening will cost about $150 million when completed, so unintended decreases in water depths are expensive as well as potentially dangerous. Lower water levels in the river also increase carbon emissions, because smaller loads mean more land and vessel transport trips. Further, navigation and salmon habitat restoration are closely connected. Dredging is used to maintain the channel, and habitat restoration is an integral part of the channel deepening. New dredging strategies are needed to maintain the newly deepened channel, but dredging that removes material permanently from the river may, further lower water levels, limiting possibilities for habitat restoration and reducing bed clearance for large ships. These problems will be exacerbated by future decreases in summer river flows due to climate change. Title: Maintaining Safe, Efficient and Sustainable Intermodal Transport Through the Port of Portland Author: Jay, David A., Pan, Jiayi Year: 2011 About $15 billion of freight passes annually through the Lower Columbia River (LCR) navigation channel to reach Portland and Vancouver, where most of it connects with land transport. This commerce plays a vital role in sustaining the regional economy and connecting Oregon to the global economy. The timely connection of truck and rail transport with vessels is vital, especially for export traffic. This link is susceptible to disruption if water depths in the navigation channel are shallower than expected, leading to delays and/or draft limitations. Moreover, ship drafts have increased in recent decades, 25% of the vessels calling in the river sail with a draft close to the channel depth at low water, and these carry roughly 70% of the cargo. A large vessel may have as little as 0.6 m bed clearance when it passes through a low-tide point in the river, which each vessel in transit must do. Thus, prediction and real-time communication of water level to vessels is vital to safety as well as efficiency. This has been implemented through the LOADMAX system, consisting of telemetered water-level gauges and a forecast model. Moreover, the dilemma has been made more critical by changes in the river – low water levels in the river channel between Wauna and Vancouver have decreased 0.3-1.2 m since 1940. The rate of decrease depends on location and riverflow, but appears to have accelerated in the last decade. The reasons for this decrease are not understood. For perspective, an ongoing 0.9 m channel deepening will cost about $150 million when completed, so unintended decreases in water depths are expensive as well as potentially dangerous. Lower water levels in the river also increase carbon emissions, because smaller loads mean more land and vessel transport trips. Further, navigation and salmon habitat restoration are closely connected. Dredging is used to maintain the channel, and habitat restoration is an integral part of the channel deepening. New dredging strategies are needed to maintain the newly deepened channel, but dredging that removes material permanently from the river may, further lower water levels, limiting possibilities for habitat restoration and reducing bed clearance for large ships. These problems will be exacerbated by future decreases in summer river flows due to climate change. Close

• 38. [Article] Trace Metals in Stormwater: Alternative Best Management Practices

  Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate ...

  Citation × Citation Citation Abstract Copy Title: Trace Metals in Stormwater: Alternative Best Management Practices Author: Mora, Jennifer Ibeth Year: 2017 Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate the heavy metal (Cu and Zn) removal efficiency of perlite and EarthliteTM to improve in-situ filtration systems for stormwater catchment basins. Stormwater samples from two field sites in Portland, OR, chosen to represent a high-use commercial site and high-traffic urban road, were characterized to inform experimental design and compare to values found in literature. The Linear, Freundlich, and Langmuir isotherm models were used to describe equilibrium data and determine partitioning coefficients for single metal batch studies. Both the Freundlich and Langmuir models fit most single metal batch systems, while Cu-Perlite, Zn-Perlite, and Zn-EarthliteTM, were best fit by the Langmuir model, R2 = 0.9594; 0.9538; 0.9811, respectively. Competitive adsorption behaviors for Cu and Zn were evaluated using a synthetic stormwater recipe where relative concentrations of Cu and Zn were maintained to be consistent with representative stormwater samples. Perlite showed a decrease in the sorption capacity of Cu and Zn in the presence of competing ions in solution. EarthliteTM showed no difference in the affinity for copper uptake between competitive and non-competitive batch experiments. EarthliteTM affinity for Zn decreased by two orders of magnitude in the competitive batch system. The results from this study will be applied to estimate filter lifetime for traditional and advanced stormwater filter systems. These results will inform experimental design in dynamic flow-through experiments using various filter media thereby improving filter design and implementation of stormwater best management practices. Title: Trace Metals in Stormwater: Alternative Best Management Practices Author: Mora, Jennifer Ibeth Year: 2017 Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate the heavy metal (Cu and Zn) removal efficiency of perlite and EarthliteTM to improve in-situ filtration systems for stormwater catchment basins. Stormwater samples from two field sites in Portland, OR, chosen to represent a high-use commercial site and high-traffic urban road, were characterized to inform experimental design and compare to values found in literature. The Linear, Freundlich, and Langmuir isotherm models were used to describe equilibrium data and determine partitioning coefficients for single metal batch studies. Both the Freundlich and Langmuir models fit most single metal batch systems, while Cu-Perlite, Zn-Perlite, and Zn-EarthliteTM, were best fit by the Langmuir model, R2 = 0.9594; 0.9538; 0.9811, respectively. Competitive adsorption behaviors for Cu and Zn were evaluated using a synthetic stormwater recipe where relative concentrations of Cu and Zn were maintained to be consistent with representative stormwater samples. Perlite showed a decrease in the sorption capacity of Cu and Zn in the presence of competing ions in solution. EarthliteTM showed no difference in the affinity for copper uptake between competitive and non-competitive batch experiments. EarthliteTM affinity for Zn decreased by two orders of magnitude in the competitive batch system. The results from this study will be applied to estimate filter lifetime for traditional and advanced stormwater filter systems. These results will inform experimental design in dynamic flow-through experiments using various filter media thereby improving filter design and implementation of stormwater best management practices. Close

• 39. [Article] Asymmetry of Tidal Plume Fronts in an Eastern Boundary Current Regime

  The Columbia River tidal plume or near-field is formed twice daily by the ebb outflow of the Columbia River. It is a part of a larger, anticyclonic plume bulge, which in turn is embedded in far-field plume ...

  Citation × Citation Citation Abstract Copy Title: Asymmetry of Tidal Plume Fronts in an Eastern Boundary Current Regime Author: Jay, David A., Pan, Jiayi, Orton, Philip M., Horner-Devine, Alexander R. Year: 2006 The Columbia River tidal plume or near-field is formed twice daily by the ebb outflow of the Columbia River. It is a part of a larger, anticyclonic plume bulge, which in turn is embedded in far-field plume and coastal waters. Because of the mixing caused directly and indirectly by plume fronts, the interaction of the tidal plume and bulge with the California Current upwelling regime plays a vital role in coastal productivity on the Oregon and Washington shelves. The tidal plume is initially supercritical with respect to the internal Froude number on all stronger ebbs. It is separated from the plume bulge by a front, whose properties are very different under upwelling vs. downwelling conditions. Under summer upwelling conditions, this front is sharp and narrow (only 50-100 m wide on its upwind or northern side) and marks a transition from supercritical to subcritical flow for 6-12 hours after high water. This sharp front is a source of turbulent mixing, despite the strong stratification. Because the tidal plume may overlie newly upwelled waters, these fronts can mix nutrients into the plume, enhancing primary productivity. Symmetry would suggest that there should be a sharp front south of the estuary mouth under summer downwelling conditions. Instead, the downwelling tidal plume front is usually broad (up to several km) and diffuse on the upstream side. Less mixing occurs, and the water immediately below the plume consists of old plume and surface ocean waters, both low in nutrients. There is also a second up-welling-downwelling asymmetry. Supercritical upwelling plume fronts often generate solitons trains as they slow and transition to a subcritical state. These soliton trains contribute to vertical mixing in the plume bulge and have a non-zero Stokes drift so that they transport low-salinity water across the tidal plume into the plume bulge. Under downwelling conditions, soliton forma-tion is uncommon. Moreover, solition formation almost always begins on the south side of the plume so that the front "unzips" from south to north. This implies that a frontal transition from supercritical to subcritical conditions first occurs on the south side tidal plume, regardless of whether this is the upwind or downwind side of the plume. This contribution describes and analyzes these two asymmetries using vessel data, SAR images and a vorticity analysis. Internal Froude number and plume depth are key parameters in distinguishing the upwelling and downwelling situations, and the observed asymmetries can be explained in terms of potential vorticity conservation. The tidal outflow embeds relative vorticity in the emerging tidal plume water mass. This vorticity controls the transition of the tidal plume front to a subcritical state and the timing and location of internal wave generation by plume fronts. Title: Asymmetry of Tidal Plume Fronts in an Eastern Boundary Current Regime Author: Jay, David A., Pan, Jiayi, Orton, Philip M., Horner-Devine, Alexander R. Year: 2006 The Columbia River tidal plume or near-field is formed twice daily by the ebb outflow of the Columbia River. It is a part of a larger, anticyclonic plume bulge, which in turn is embedded in far-field plume and coastal waters. Because of the mixing caused directly and indirectly by plume fronts, the interaction of the tidal plume and bulge with the California Current upwelling regime plays a vital role in coastal productivity on the Oregon and Washington shelves. The tidal plume is initially supercritical with respect to the internal Froude number on all stronger ebbs. It is separated from the plume bulge by a front, whose properties are very different under upwelling vs. downwelling conditions. Under summer upwelling conditions, this front is sharp and narrow (only 50-100 m wide on its upwind or northern side) and marks a transition from supercritical to subcritical flow for 6-12 hours after high water. This sharp front is a source of turbulent mixing, despite the strong stratification. Because the tidal plume may overlie newly upwelled waters, these fronts can mix nutrients into the plume, enhancing primary productivity. Symmetry would suggest that there should be a sharp front south of the estuary mouth under summer downwelling conditions. Instead, the downwelling tidal plume front is usually broad (up to several km) and diffuse on the upstream side. Less mixing occurs, and the water immediately below the plume consists of old plume and surface ocean waters, both low in nutrients. There is also a second up-welling-downwelling asymmetry. Supercritical upwelling plume fronts often generate solitons trains as they slow and transition to a subcritical state. These soliton trains contribute to vertical mixing in the plume bulge and have a non-zero Stokes drift so that they transport low-salinity water across the tidal plume into the plume bulge. Under downwelling conditions, soliton forma-tion is uncommon. Moreover, solition formation almost always begins on the south side of the plume so that the front "unzips" from south to north. This implies that a frontal transition from supercritical to subcritical conditions first occurs on the south side tidal plume, regardless of whether this is the upwind or downwind side of the plume. This contribution describes and analyzes these two asymmetries using vessel data, SAR images and a vorticity analysis. Internal Froude number and plume depth are key parameters in distinguishing the upwelling and downwelling situations, and the observed asymmetries can be explained in terms of potential vorticity conservation. The tidal outflow embeds relative vorticity in the emerging tidal plume water mass. This vorticity controls the transition of the tidal plume front to a subcritical state and the timing and location of internal wave generation by plume fronts. Close

• 40. [Article] Improvements in Modeling Dissolved Oxygen in Activated Sludge Systems

  The aim of this research was to show the impact of the flow conditions and variations in the aeration intensity on changes in the predicted dissolved oxygen (DO) concentrations in a full-scale activated ...

  Citation × Citation Citation Abstract Copy Title: Improvements in Modeling Dissolved Oxygen in Activated Sludge Systems Author: Makinia, Jacek, Wells, Scott A. Year: 1999 The aim of this research was to show the impact of the flow conditions and variations in the aeration intensity on changes in the predicted dissolved oxygen (DO) concentrations in a full-scale activated sludge reactor. The Activated Sludge Model No. 1 was used to describe the biochemical processes. The studies were performed at the Rock Creek wastewater treatment plant in Hillsboro, OR (USA). The simulation results were compared with data originating from two 24-hour experiments. The model that best reflected the spatial and diurnal distributions of the DO concentrations was the one-dimensional advection-dispersion equation with a variable overall oxygen mass transfer coefficient in the source term for dissolved oxygen. Title: Improvements in Modeling Dissolved Oxygen in Activated Sludge Systems Author: Makinia, Jacek, Wells, Scott A. Year: 1999 The aim of this research was to show the impact of the flow conditions and variations in the aeration intensity on changes in the predicted dissolved oxygen (DO) concentrations in a full-scale activated sludge reactor. The Activated Sludge Model No. 1 was used to describe the biochemical processes. The studies were performed at the Rock Creek wastewater treatment plant in Hillsboro, OR (USA). The simulation results were compared with data originating from two 24-hour experiments. The model that best reflected the spatial and diurnal distributions of the DO concentrations was the one-dimensional advection-dispersion equation with a variable overall oxygen mass transfer coefficient in the source term for dissolved oxygen. Close