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• 1. [Article] Occurrence of Synthetic Amino-Polycarboxylate Chelating Compounds in Oregon Surface Waters

  Cation sequestering compounds are contained in many industrial, commercial and personal care products. The most widely used chelating agents, EDTA and DTPA, are commonly found in natural and industrial ...

  Citation × Citation Citation Abstract Copy Title: Occurrence of Synthetic Amino-Polycarboxylate Chelating Compounds in Oregon Surface Waters Author: Hersey, Nathan A Year: 2014 Cation sequestering compounds are contained in many industrial, commercial and personal care products. The most widely used chelating agents, EDTA and DTPA, are commonly found in natural and industrial settings. When chelating compounds are present, the activity and transport of metal cations in the environment and the uptake of metals in natural systems can be affected. Surface water samples from across the United States were analyzed, as well as local collection and analysis of surface waters and wastewater treatment plant effluent from around Northwest Oregon. Results indicate presence of synthetic chelating compounds in areas with human activity, and absence in areas that are less populated. As a stable and water soluble compound, monitoring for chelates could have potential use as an effective indicator of further anthropogenic effects. Title: Occurrence of Synthetic Amino-Polycarboxylate Chelating Compounds in Oregon Surface Waters Author: Hersey, Nathan A Year: 2014 Cation sequestering compounds are contained in many industrial, commercial and personal care products. The most widely used chelating agents, EDTA and DTPA, are commonly found in natural and industrial settings. When chelating compounds are present, the activity and transport of metal cations in the environment and the uptake of metals in natural systems can be affected. Surface water samples from across the United States were analyzed, as well as local collection and analysis of surface waters and wastewater treatment plant effluent from around Northwest Oregon. Results indicate presence of synthetic chelating compounds in areas with human activity, and absence in areas that are less populated. As a stable and water soluble compound, monitoring for chelates could have potential use as an effective indicator of further anthropogenic effects. Close

• 2. [Article] Nonstationary Internal Tides Observed Using Dual-Satellite Altimetry

  Dual-satellite crossover data from the Jason-2 and Cryosat-2 altimeter missions are used in a novel approach to quantify stationary and nonstationary tides from time-lagged mean square sea surface height ...

  Citation × Citation Citation Abstract Copy Title: Nonstationary Internal Tides Observed Using Dual-Satellite Altimetry Author: Zaron, Edward D. Year: 2015 Dual-satellite crossover data from the Jason-2 and Cryosat-2 altimeter missions are used in a novel approach to quantify stationary and nonstationary tides from time-lagged mean square sea surface height (SSH) differences, computed for lags from 1 to 1440 h (60 days). The approach is made feasible by removing independent estimates of the stationary tide and mesoscale SSH variance, which greatly reduces the sampling error of the SSH statistics. For the semidiurnal tidal band, the stationary tidal variance is approximately 0.73 cm(2), and the nonstationary variance is about 0.33 cm(2), or 30% of the total. The temporal correlation of the nonstationary tide is examined by complex demodulation and found to be oscillatory with first 0 crossing at 400 h (17 days). Because a significant fraction of the time-variable mesoscale signal is resolved at time scales of roughly 150 h by the present constellation of satellite altimeters, the results suggest that it may be feasible to predict the nonstationary tide from modulations of the resolved mesoscale, thus enhancing the efficacy of tidal corrections for planned wide-swath altimeters such as the Surface Water and Ocean Topography (SWOT) mission. Title: Nonstationary Internal Tides Observed Using Dual-Satellite Altimetry Author: Zaron, Edward D. Year: 2015 Dual-satellite crossover data from the Jason-2 and Cryosat-2 altimeter missions are used in a novel approach to quantify stationary and nonstationary tides from time-lagged mean square sea surface height (SSH) differences, computed for lags from 1 to 1440 h (60 days). The approach is made feasible by removing independent estimates of the stationary tide and mesoscale SSH variance, which greatly reduces the sampling error of the SSH statistics. For the semidiurnal tidal band, the stationary tidal variance is approximately 0.73 cm(2), and the nonstationary variance is about 0.33 cm(2), or 30% of the total. The temporal correlation of the nonstationary tide is examined by complex demodulation and found to be oscillatory with first 0 crossing at 400 h (17 days). Because a significant fraction of the time-variable mesoscale signal is resolved at time scales of roughly 150 h by the present constellation of satellite altimeters, the results suggest that it may be feasible to predict the nonstationary tide from modulations of the resolved mesoscale, thus enhancing the efficacy of tidal corrections for planned wide-swath altimeters such as the Surface Water and Ocean Topography (SWOT) mission. Close

• 3. [Article] A Method for Processing Acoustic Doppler Current Profiler Velocity Data from Towed, Undulating Vehicles

  The utility of the acoustic Doppler current profiler (ADCP) for sampling small time and space scales of coastal environments can be enhanced by mounting a high-frequency (1200 kHz) ADCP on an oscillating ...

  Citation × Citation Citation Abstract Copy Title: A Method for Processing Acoustic Doppler Current Profiler Velocity Data from Towed, Undulating Vehicles Author: Jay, David A., Pan, Jiayi Year: 2008 The utility of the acoustic Doppler current profiler (ADCP) for sampling small time and space scales of coastal environments can be enhanced by mounting a high-frequency (1200 kHz) ADCP on an oscillating towed body. This approach requires both an external reference to convert the measured shears to velocities in the earth coordinates and a method to determine the towed body velocities. During the River Influence on the Shelf Ecosystems (RISE) project cruise, a high-frequency (1200 kHz) and narrowbeam ADCP with mode 12 sampling was mounted on a TRIAXUS oscillating towfish, which steers a 3D path behind the ship. This deployment approach extended the vertical range of the ADCP and allowed it to sample near-surface waters outside the ship?s wake. The measurements from a ship-mounted 1200-kHz narrowbeam ADCP are used as references for TRIAXUS ADCP data, and a method of overlapping bins is employed to recover the entire vertical range of the TRIAXUS ADCP. The TRIAXUS vehicle horizontal velocities are obtained by removing the derived ocean current velocity from the TRIAXUS ADCP measurements. The results show that the method is practical. Title: A Method for Processing Acoustic Doppler Current Profiler Velocity Data from Towed, Undulating Vehicles Author: Jay, David A., Pan, Jiayi Year: 2008 The utility of the acoustic Doppler current profiler (ADCP) for sampling small time and space scales of coastal environments can be enhanced by mounting a high-frequency (1200 kHz) ADCP on an oscillating towed body. This approach requires both an external reference to convert the measured shears to velocities in the earth coordinates and a method to determine the towed body velocities. During the River Influence on the Shelf Ecosystems (RISE) project cruise, a high-frequency (1200 kHz) and narrowbeam ADCP with mode 12 sampling was mounted on a TRIAXUS oscillating towfish, which steers a 3D path behind the ship. This deployment approach extended the vertical range of the ADCP and allowed it to sample near-surface waters outside the ship?s wake. The measurements from a ship-mounted 1200-kHz narrowbeam ADCP are used as references for TRIAXUS ADCP data, and a method of overlapping bins is employed to recover the entire vertical range of the TRIAXUS ADCP. The TRIAXUS vehicle horizontal velocities are obtained by removing the derived ocean current velocity from the TRIAXUS ADCP measurements. The results show that the method is practical. Close

• 4. [Article] The Small Volume Autonomous Water Sampler (SVAWS): An Innovative, Cost- Effective, Adaptable Protocol

  As of 2007, U.S. pesticide use stood at 1.1 billion pounds with 80% of all usage in agriculture. Such realities pose a potentially dangerous threat to our surface water bodies. This research provides a ...

  Citation × Citation Citation Abstract Copy Title: The Small Volume Autonomous Water Sampler (SVAWS): An Innovative, Cost- Effective, Adaptable Protocol Author: Fitzgerald, Nicholas B Year: 2014 As of 2007, U.S. pesticide use stood at 1.1 billion pounds with 80% of all usage in agriculture. Such realities pose a potentially dangerous threat to our surface water bodies. This research provides a detailed analysis of the design, operation and field testing of a prototype water sampler, the Small Volume Autonomous Water Sampler (SVAWS). The research includes a discussion of the design and construction of the SVAWS. Seven USGS employees operated the SVAWS in a number of different states and conditions in order to collect samples for pesticide analysis. Field-testing outcomes of the SVAWS were measured through a Participant Survey Request and a Likert-Scale Assessment. Overall, survey data proved the SVAWS to be an effective device for collecting water samples in different locations and conditions. Users also understood the SVAWS has significant potential for applications other than pesticide studies. While feedback did show a number of alterations or modifications could improve the design, the device proved to be effective across many of its goals, from valid water sampling to reducing costs of sample acquisition. Recommendations for future research include these and other avenues of research. A conclusion addresses the potential future of the SVAWS with respect to water sampling applications. Title: The Small Volume Autonomous Water Sampler (SVAWS): An Innovative, Cost- Effective, Adaptable Protocol Author: Fitzgerald, Nicholas B Year: 2014 As of 2007, U.S. pesticide use stood at 1.1 billion pounds with 80% of all usage in agriculture. Such realities pose a potentially dangerous threat to our surface water bodies. This research provides a detailed analysis of the design, operation and field testing of a prototype water sampler, the Small Volume Autonomous Water Sampler (SVAWS). The research includes a discussion of the design and construction of the SVAWS. Seven USGS employees operated the SVAWS in a number of different states and conditions in order to collect samples for pesticide analysis. Field-testing outcomes of the SVAWS were measured through a Participant Survey Request and a Likert-Scale Assessment. Overall, survey data proved the SVAWS to be an effective device for collecting water samples in different locations and conditions. Users also understood the SVAWS has significant potential for applications other than pesticide studies. While feedback did show a number of alterations or modifications could improve the design, the device proved to be effective across many of its goals, from valid water sampling to reducing costs of sample acquisition. Recommendations for future research include these and other avenues of research. A conclusion addresses the potential future of the SVAWS with respect to water sampling applications. Close

• 5. [Article] Non-Stationary Internal Tides Observed with Satellite Altimetry

  Temporal variability of the internal tide is inferred from a 17-year combined record of Topex/Poseidon and Jason satellite altimeters. A global sampling of along-track sea-surface height wavenumber spectra ...

  Citation × Citation Citation Abstract Copy Title: Non-Stationary Internal Tides Observed with Satellite Altimetry Author: Ray, R. D., Zaron, Edward D. Year: 2011 Temporal variability of the internal tide is inferred from a 17-year combined record of Topex/Poseidon and Jason satellite altimeters. A global sampling of along-track sea-surface height wavenumber spectra finds that non-stationary variance is generally 25% or less of the average variance at wavenumbers characteristic of mode-1 tidal internal waves. With some exceptions the non-stationary variance does not exceed 0.25 cm2. The mode-2 signal, where detectable, contains a larger fraction of non-stationary variance, typically 50% or more. Temporal subsetting of the data reveals interannual variability barely significant compared with tidal estimation error from 3-year records. Comparison of summer vs. winter conditions shows only one region of noteworthy seasonal changes, the northern South China Sea. Implications for the anticipated SWOT altimeter mission are briefly discussed. Title: Non-Stationary Internal Tides Observed with Satellite Altimetry Author: Ray, R. D., Zaron, Edward D. Year: 2011 Temporal variability of the internal tide is inferred from a 17-year combined record of Topex/Poseidon and Jason satellite altimeters. A global sampling of along-track sea-surface height wavenumber spectra finds that non-stationary variance is generally 25% or less of the average variance at wavenumbers characteristic of mode-1 tidal internal waves. With some exceptions the non-stationary variance does not exceed 0.25 cm2. The mode-2 signal, where detectable, contains a larger fraction of non-stationary variance, typically 50% or more. Temporal subsetting of the data reveals interannual variability barely significant compared with tidal estimation error from 3-year records. Comparison of summer vs. winter conditions shows only one region of noteworthy seasonal changes, the northern South China Sea. Implications for the anticipated SWOT altimeter mission are briefly discussed. Close

• 6. [Article] Regional Models of Internal Tides

  Internal tides are ubiquitous in the ocean, and they play an important role in a range of ocean processes, for example, particle dispersal, acoustics, and vertical buoyancy flux. The wavelength of internal ...

  Citation × Citation Citation Abstract Copy Title: Regional Models of Internal Tides Author: Carter, Glenn S., Fringer, Oliver B., Zaron, Edward D. Year: 2012 Internal tides are ubiquitous in the ocean, and they play an important role in a range of ocean processes, for example, particle dispersal, acoustics, and vertical buoyancy flux. The wavelength of internal tides can be as much as 250 km in the open ocean, but as the generation of these tides depends on the angle between the depth-averaged current and the topography, there can be considerable local spatial variability. This range of scales makes it difficult to develop a comprehensive understanding of the processes involved from observations alone. Regional numerical modeling provides a way to study the generation and early propagation of internal tides at high resolution. Here, we review the role that regional internal tide models, primarily hydrostatic models, can play in increasing our understanding. Title: Regional Models of Internal Tides Author: Carter, Glenn S., Fringer, Oliver B., Zaron, Edward D. Year: 2012 Internal tides are ubiquitous in the ocean, and they play an important role in a range of ocean processes, for example, particle dispersal, acoustics, and vertical buoyancy flux. The wavelength of internal tides can be as much as 250 km in the open ocean, but as the generation of these tides depends on the angle between the depth-averaged current and the topography, there can be considerable local spatial variability. This range of scales makes it difficult to develop a comprehensive understanding of the processes involved from observations alone. Regional numerical modeling provides a way to study the generation and early propagation of internal tides at high resolution. Here, we review the role that regional internal tide models, primarily hydrostatic models, can play in increasing our understanding. Close

• 7. [Article] Potential Impacts of Climate Change on Flood-Induced Travel Disruptions: A Case Study of Portland, Oregon, USA

  This study investigated potential impacts of climate change on travel disruption resulting from road closures in two urban watersheds in the Portland, Oregon, metropolitan area. We used ensemble climate ...

  Citation × Citation Citation Abstract Copy Title: Potential Impacts of Climate Change on Flood-Induced Travel Disruptions: A Case Study of Portland, Oregon, USA Author: Chang, Heejun, Lafrenz, Martin, Jung, Il-won, Figliozzi, Miguel, Platman, Deena, Pederson, Cindy Year: 2010 This study investigated potential impacts of climate change on travel disruption resulting from road closures in two urban watersheds in the Portland, Oregon, metropolitan area. We used ensemble climate change scenarios, a hydrologic model, a stream channel survey, a hydraulic model, and a travel forecast model to develop an integrated impact assessment method. High-resolution climate change scenarios are based on the combinations of two emission scenarios and eight general circulation models. The Precipitation-Runoff Modeling System was calibrated and validated for the historical period of 1988 and 2006 and simulated for determining the probability of floods for 2020 through 2049. We surveyed stream cross-sections at five road crossings for stream channel geometry and determined flood water surface elevations using the Hydrologic Engineering Centers River Analysis System (HEC-RAS) model. Four of the surveyed bridges and roadways were lower in elevation than the current 100-year flood water surface elevation, leading to relatively frequent nuisance flooding. These roadway flooding events will become more frequent under some climate change scenarios in the future, but climate change impacts will depend on local geomorphic conditions. Whereas vehicle miles traveled was not significantly affected by road closure, vehicle hours delay demonstrated a greater impact from road closures, increasing by 10 percent in the Fanno Creek area. Our research demonstrated the usefulness of the integration of top-down and bottom-up approaches in climate change impact assessment and the need for spatially explicit modeling and participatory planning in flood management and transportation planning under increasing climate uncertainty. Title: Potential Impacts of Climate Change on Flood-Induced Travel Disruptions: A Case Study of Portland, Oregon, USA Author: Chang, Heejun, Lafrenz, Martin, Jung, Il-won, Figliozzi, Miguel, Platman, Deena, Pederson, Cindy Year: 2010 This study investigated potential impacts of climate change on travel disruption resulting from road closures in two urban watersheds in the Portland, Oregon, metropolitan area. We used ensemble climate change scenarios, a hydrologic model, a stream channel survey, a hydraulic model, and a travel forecast model to develop an integrated impact assessment method. High-resolution climate change scenarios are based on the combinations of two emission scenarios and eight general circulation models. The Precipitation-Runoff Modeling System was calibrated and validated for the historical period of 1988 and 2006 and simulated for determining the probability of floods for 2020 through 2049. We surveyed stream cross-sections at five road crossings for stream channel geometry and determined flood water surface elevations using the Hydrologic Engineering Centers River Analysis System (HEC-RAS) model. Four of the surveyed bridges and roadways were lower in elevation than the current 100-year flood water surface elevation, leading to relatively frequent nuisance flooding. These roadway flooding events will become more frequent under some climate change scenarios in the future, but climate change impacts will depend on local geomorphic conditions. Whereas vehicle miles traveled was not significantly affected by road closure, vehicle hours delay demonstrated a greater impact from road closures, increasing by 10 percent in the Fanno Creek area. Our research demonstrated the usefulness of the integration of top-down and bottom-up approaches in climate change impact assessment and the need for spatially explicit modeling and participatory planning in flood management and transportation planning under increasing climate uncertainty. Close

• 8. [Article] Bottom Topography Mapping via Nonlinear Data Assimilation

  A variational data assimilation method is described for bottom topography mapping in rivers and estuaries using remotely sensed observations of water surface currents. The velocity field and bottom topography ...

  Citation × Citation Citation Abstract Copy Title: Bottom Topography Mapping via Nonlinear Data Assimilation Author: Zaron, Edward D., Pradal, Marie-Aude, Miller, Patrick D., Blumberg, Alan F., Georgas, Nickitas, Li, Wei, Cornuelle, Julia Muccino Year: 2011 A variational data assimilation method is described for bottom topography mapping in rivers and estuaries using remotely sensed observations of water surface currents. The velocity field and bottom topography are related by the vertically integrated momentum and continuity equations, leading to a nonlinear inverse problem for bottom topography, which is solved using a Picard iteration strategy combined with a nonlinear line search. An illustration of the method is shown for Haverstraw Bay, in the Hudson River, where the known bottom topography is well reconstructed. Once the topography has been estimated, currents and water levels may be forecast. The method makes feasible 1) the estimation of bottom topography in regions where in situ data collection may be impossible, dangerous, or expensive, and 2) the calibration of barotropic shallow-water models via control of the bottom topography. Title: Bottom Topography Mapping via Nonlinear Data Assimilation Author: Zaron, Edward D., Pradal, Marie-Aude, Miller, Patrick D., Blumberg, Alan F., Georgas, Nickitas, Li, Wei, Cornuelle, Julia Muccino Year: 2011 A variational data assimilation method is described for bottom topography mapping in rivers and estuaries using remotely sensed observations of water surface currents. The velocity field and bottom topography are related by the vertically integrated momentum and continuity equations, leading to a nonlinear inverse problem for bottom topography, which is solved using a Picard iteration strategy combined with a nonlinear line search. An illustration of the method is shown for Haverstraw Bay, in the Hudson River, where the known bottom topography is well reconstructed. Once the topography has been estimated, currents and water levels may be forecast. The method makes feasible 1) the estimation of bottom topography in regions where in situ data collection may be impossible, dangerous, or expensive, and 2) the calibration of barotropic shallow-water models via control of the bottom topography. Close

• 9. [Article] A Comparison of Five Models for Estimating Clear-Sky Solar Radiation

  Many agencies in the USA are developing management approaches to address water quality concerns and threatened and endangered species habitat requirements in water bodies. Many of these water bodies are ...

  Citation × Citation Citation Abstract Copy Title: A Comparison of Five Models for Estimating Clear-Sky Solar Radiation Author: Annear, Robert Leslie, Wells, Scott A. Year: 2007 Many agencies in the USA are developing management approaches to address water quality concerns and threatened and endangered species habitat requirements in water bodies. Many of these water bodies are water quality limited for temperature. Factors influencing stream temperature include: streamside vegetation, topographic shading, inflows and outflows, stream width, stream depth, light extinction and solar radiation. One of the key driving factors in estimating a water body heat budget is calculating the amount of solar radiation incident on the water surface. Even though it is preferable to measure clear-sky solar radiation, many temperature models rely on theoretical estimates of clear-sky solar radiation. The literature on estimating short-wave solar radiation by calculating the position of the sun and attenuating the radiation through the atmosphere was reviewed. As a first step in relating water temperature to solar radiation, several empirical solar radiation models were calibrated to data at seventeen sites around the United States for clear-sky days. Sensitivity analyses were conducted and differences between the models were examined. Results indicated that the more complex models for calculating solar radiation resulted in better estimates of clear-sky solar radiation once they were calibrated to data. When no data were available, models with one or no calibration parameters did reasonably well at estimating clear-sky solar radiation. Title: A Comparison of Five Models for Estimating Clear-Sky Solar Radiation Author: Annear, Robert Leslie, Wells, Scott A. Year: 2007 Many agencies in the USA are developing management approaches to address water quality concerns and threatened and endangered species habitat requirements in water bodies. Many of these water bodies are water quality limited for temperature. Factors influencing stream temperature include: streamside vegetation, topographic shading, inflows and outflows, stream width, stream depth, light extinction and solar radiation. One of the key driving factors in estimating a water body heat budget is calculating the amount of solar radiation incident on the water surface. Even though it is preferable to measure clear-sky solar radiation, many temperature models rely on theoretical estimates of clear-sky solar radiation. The literature on estimating short-wave solar radiation by calculating the position of the sun and attenuating the radiation through the atmosphere was reviewed. As a first step in relating water temperature to solar radiation, several empirical solar radiation models were calibrated to data at seventeen sites around the United States for clear-sky days. Sensitivity analyses were conducted and differences between the models were examined. Results indicated that the more complex models for calculating solar radiation resulted in better estimates of clear-sky solar radiation once they were calibrated to data. When no data were available, models with one or no calibration parameters did reasonably well at estimating clear-sky solar radiation. Close

• 10. [Article] Idaho Pend Oreille River Model: Model Development and Calibration

  The objectives of this project were to: • Develop a hydrodynamic and temperature model of Pend Oreille River using CE-QUAL-W2 Version 3.2 • Calibrate the CE-QUAL-W2 model to field data collected during ...

  Citation × Citation Citation Abstract Copy Title: Idaho Pend Oreille River Model: Model Development and Calibration Author: Annear, Robert Leslie, Berger, Chris, Wells, Scott A. Year: 2006 The objectives of this project were to: • Develop a hydrodynamic and temperature model of Pend Oreille River using CE-QUAL-W2 Version 3.2 • Calibrate the CE-QUAL-W2 model to field data collected during 2004 and 2005 using the following water quality variables: flow, water surface elevation, and velocity temperature o dissolved oxygen nutrients (NO3-N+NO2-N, NH4-N, PO4-P) algae – chlorophyll a BOD5 and dissolved organic matter and particulate organic matter compartments (both labile and refractory) for the organic matter cycling with algae periphyton The model chosen for development was CE-QUAL-W2 Version 3.2 (Cole and Wells, 2004). This is a two-dimensional unsteady hydrodynamic and water quality model that includes typical eutrophication constituents (algae, nutrients, temperature, organic matter, dissolved oxygen, pH). Portland State University’s Water Quality Research Group is a center for development of this modeling tool (see http://www.cee.pdx.edu/w2). The model simulation was run from January 1st, 2004 to September 25th, 2005. The calibration period focused on the summers during each year when water quality data were obtained. Title: Idaho Pend Oreille River Model: Model Development and Calibration Author: Annear, Robert Leslie, Berger, Chris, Wells, Scott A. Year: 2006 The objectives of this project were to: • Develop a hydrodynamic and temperature model of Pend Oreille River using CE-QUAL-W2 Version 3.2 • Calibrate the CE-QUAL-W2 model to field data collected during 2004 and 2005 using the following water quality variables: flow, water surface elevation, and velocity temperature o dissolved oxygen nutrients (NO3-N+NO2-N, NH4-N, PO4-P) algae – chlorophyll a BOD5 and dissolved organic matter and particulate organic matter compartments (both labile and refractory) for the organic matter cycling with algae periphyton The model chosen for development was CE-QUAL-W2 Version 3.2 (Cole and Wells, 2004). This is a two-dimensional unsteady hydrodynamic and water quality model that includes typical eutrophication constituents (algae, nutrients, temperature, organic matter, dissolved oxygen, pH). Portland State University’s Water Quality Research Group is a center for development of this modeling tool (see http://www.cee.pdx.edu/w2). The model simulation was run from January 1st, 2004 to September 25th, 2005. The calibration period focused on the summers during each year when water quality data were obtained. Close

• 11. [Article] Analysis of Landsat Satellite Data to Monitor Water Quality Parameters in Tenmile Lake, Oregon

  The health of North and South Tenmile Lakes in coastal Oregon has declined since the introduction of invasive species of fish and plant life in the 1920s. The lakes are now on the Federal Clean Water Act ...

  Citation × Citation Citation Abstract Copy Title: Analysis of Landsat Satellite Data to Monitor Water Quality Parameters in Tenmile Lake, Oregon Author: Waxter, Michael T. Year: 2014 The health of North and South Tenmile Lakes in coastal Oregon has declined since the introduction of invasive species of fish and plant life in the 1920s. The lakes are now on the Federal Clean Water Act list of impaired water bodies due, in part, to a lack of dissolved oxygen and Hazardous Algae Blooms (HAB) blooms that occur during June through September. In this report we discuss the possibility of detecting and monitoring these blooms using satellite measurements of water surface color. In-situ measurements obtained from the Tenmile Lakes Basin Partnership were used to calibrate reflectance from the Thematic Mapper on the Landsat 5 satellite. Results show a good linear correlation between turbidity and radiance, which are inversely related in algal dominated lakes. Additionally, a correlation between biovolume and reflectance was obtained. Spatial patterns of turbidity and biovolume are observed, with large concentrations observed in lake areas with large residence times. The comparatively lowest concentrations are observed along the probable pathway of cleaner water input by creeks into the lake. However, the ability to predict turbidity and biovolume from satellite reflectance data is currently complicated by the lack of coincident in-situ and satellite data, and the limited number of spectral bands available to separate turbidity from different species of bacteria and algae. Title: Analysis of Landsat Satellite Data to Monitor Water Quality Parameters in Tenmile Lake, Oregon Author: Waxter, Michael T. Year: 2014 The health of North and South Tenmile Lakes in coastal Oregon has declined since the introduction of invasive species of fish and plant life in the 1920s. The lakes are now on the Federal Clean Water Act list of impaired water bodies due, in part, to a lack of dissolved oxygen and Hazardous Algae Blooms (HAB) blooms that occur during June through September. In this report we discuss the possibility of detecting and monitoring these blooms using satellite measurements of water surface color. In-situ measurements obtained from the Tenmile Lakes Basin Partnership were used to calibrate reflectance from the Thematic Mapper on the Landsat 5 satellite. Results show a good linear correlation between turbidity and radiance, which are inversely related in algal dominated lakes. Additionally, a correlation between biovolume and reflectance was obtained. Spatial patterns of turbidity and biovolume are observed, with large concentrations observed in lake areas with large residence times. The comparatively lowest concentrations are observed along the probable pathway of cleaner water input by creeks into the lake. However, the ability to predict turbidity and biovolume from satellite reflectance data is currently complicated by the lack of coincident in-situ and satellite data, and the limited number of spectral bands available to separate turbidity from different species of bacteria and algae. Close

• 12. [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

• 13. [Article] On the Observability of Bottom Topography from Measurements of Tidal Sea Surface Height

  of whether features of the ocean bottom topography can be identified from measurements of water level is investigated using a simplified one-dimensional barotropic model. Because of the nonlinear dependence ...

  Citation × Citation Citation Abstract Copy Title: On the Observability of Bottom Topography from Measurements of Tidal Sea Surface Height Author: Zaron, Edward D. Year: 2016 of whether features of the ocean bottom topography can be identified from measurements of water level is investigated using a simplified one-dimensional barotropic model. Because of the nonlinear dependence of the sea surface height on the water depth, a linearized analysis is performed concerning the identification of a Gaussian bump within two specific depth profiles, (1) a constant depth domain, and, (2) a constant depth domain adjoining a near-resonant continental shelf. Observability is quantified by examining the estimation error in a series of identical-twin experiments varying data density, tide wavelength, assumed (versus actual) topographic correlation scale, and friction. For measurements of sea surface height that resolve the scale of the topographic perturbation, the fractional error in the bottom topography is approximately a factor of 10 larger than the fractional error of the sea surface height. Domain-scale and shelf-scale resonances may lead to inaccurate topography estimates due to a reduction in the effective number of degrees of freedom in the dynamics, and the amplification of nonlinearity. A realizability condition for the variance of the topography error in the limit of zero bottom depth is proposed which is interpreted as a bound on the fractional error of the topography. Appropriately designed spatial covariance models partly ameliorate the negative impact of shelf-scale near-resonance, and highlight the importance of spatial covariance modeling for bottom topography estimation. Title: On the Observability of Bottom Topography from Measurements of Tidal Sea Surface Height Author: Zaron, Edward D. Year: 2016 of whether features of the ocean bottom topography can be identified from measurements of water level is investigated using a simplified one-dimensional barotropic model. Because of the nonlinear dependence of the sea surface height on the water depth, a linearized analysis is performed concerning the identification of a Gaussian bump within two specific depth profiles, (1) a constant depth domain, and, (2) a constant depth domain adjoining a near-resonant continental shelf. Observability is quantified by examining the estimation error in a series of identical-twin experiments varying data density, tide wavelength, assumed (versus actual) topographic correlation scale, and friction. For measurements of sea surface height that resolve the scale of the topographic perturbation, the fractional error in the bottom topography is approximately a factor of 10 larger than the fractional error of the sea surface height. Domain-scale and shelf-scale resonances may lead to inaccurate topography estimates due to a reduction in the effective number of degrees of freedom in the dynamics, and the amplification of nonlinearity. A realizability condition for the variance of the topography error in the limit of zero bottom depth is proposed which is interpreted as a bound on the fractional error of the topography. Appropriately designed spatial covariance models partly ameliorate the negative impact of shelf-scale near-resonance, and highlight the importance of spatial covariance modeling for bottom topography estimation. Close

• 14. [Article] Mass Exchange Dynamics of Surface and Subsurface Oil in Shallow-Water Transport

  We formulate a model for the mass exchange between oil at and below the sea surface. This is a particularly important aspect of modeling oil spills. Surface and subsurface oil have different chemical and ...

  Citation × Citation Citation Abstract Copy Title: Mass Exchange Dynamics of Surface and Subsurface Oil in Shallow-Water Transport Author: Moghimi, Saeed, Ramirez, Jorge, Restrepo, Juan M., Venkataramani, Shankar Year: 2017 We formulate a model for the mass exchange between oil at and below the sea surface. This is a particularly important aspect of modeling oil spills. Surface and subsurface oil have different chemical and transport characteristics and lumping them together would compromise the accuracy of the resulting model. Without observational or computational constraints, it is thus not possible to quantitatively predict oil spills based upon partial field observations of surface and/or sub-surface oil. The primary challenge in capturing the mass exchange is that the principal mechanisms are on the microscale. This is a serious barrier to developing practical models for oil spills that are capable of addressing questions regarding the fate of oil at the large spatio-temporal scales, as demanded by environmental questions. We use upscaling to propose an environmental-scale model which incorporates the mass exchange between surface and subsurface oil due to oil droplet dynamics, buoyancy effects, and sea surface and subsurface mechanics. While the mass exchange mechanism detailed here is generally applicable to oil transport models, it addresses the modeling needs of a particular to an oil spill model [1]. This transport model is designed to capture oil spills at very large spatio-temporal scales. It accomplishes this goal by specializing to shallow-water environments, in which depth averaging is a perfectly good approximation for the flow, while at the same time retaining mass conservation of oil over the whole oceanic domain. Title: Mass Exchange Dynamics of Surface and Subsurface Oil in Shallow-Water Transport Author: Moghimi, Saeed, Ramirez, Jorge, Restrepo, Juan M., Venkataramani, Shankar Year: 2017 We formulate a model for the mass exchange between oil at and below the sea surface. This is a particularly important aspect of modeling oil spills. Surface and subsurface oil have different chemical and transport characteristics and lumping them together would compromise the accuracy of the resulting model. Without observational or computational constraints, it is thus not possible to quantitatively predict oil spills based upon partial field observations of surface and/or sub-surface oil. The primary challenge in capturing the mass exchange is that the principal mechanisms are on the microscale. This is a serious barrier to developing practical models for oil spills that are capable of addressing questions regarding the fate of oil at the large spatio-temporal scales, as demanded by environmental questions. We use upscaling to propose an environmental-scale model which incorporates the mass exchange between surface and subsurface oil due to oil droplet dynamics, buoyancy effects, and sea surface and subsurface mechanics. While the mass exchange mechanism detailed here is generally applicable to oil transport models, it addresses the modeling needs of a particular to an oil spill model [1]. This transport model is designed to capture oil spills at very large spatio-temporal scales. It accomplishes this goal by specializing to shallow-water environments, in which depth averaging is a perfectly good approximation for the flow, while at the same time retaining mass conservation of oil over the whole oceanic domain. Close

• 15. [Article] Cohstrex: Coherent Structures in Rivers and Estuaries Experiment

  COHSTREX, the Coherent Structures in Rivers and Estuaries Experiment, was a five-year project to exploit the remotely sensed signatures of coherent flow structures in rivers and estuaries. The purpose ...

  Citation × Citation Citation Abstract Copy Title: Cohstrex: Coherent Structures in Rivers and Estuaries Experiment Author: Jessup, Andrew, Chickadel, C., Talke, Stefan, Horner-Devine, Alexander Year: 2013 COHSTREX, the Coherent Structures in Rivers and Estuaries Experiment, was a five-year project to exploit the remotely sensed signatures of coherent flow structures in rivers and estuaries. The purpose of the study was to use remote-sensing measurements of coherent structures at a river surface to characterize and quantify the flow. Two major field experiments were undertaken on the Snohomish River near Everett, WA, United States. The first experiment took place near the mouth of the river where stratification was strong due to a tidally driven salt wedge. Flow over a rocky sill generated a field of boils (bottom-generated fluid upwellings) on the flow surface that propagated downstream and provided insight into mixing layer dynamics. The second experiment took place approximately 15[t#]km upstream from the mouth of the river where the tide still affected the river level and velocity, but stratification was minimal. The focus of the unstratified flow experiment was the study of boils generated by flow over flat beds and beds with a bottom roughness. Herein, we provide an overview of infrared measurements of thermal variability on the surface and in-situ measurements of turbulent velocities beneath the surface. A major finding of COHSTREX is that infrared imagery of the thermal signature of coherent flow structures in estuarine rivers is a powerful tool for visualizing and quantifying the flow. Thermal signatures include mixing of water masses with different temperatures, and disruptions of the flow surface by coherent flow structures generated by bottom roughness. Through use of particle image velocimetry (PIV) techniques applied to infrared imagery of the river surface, we are able to estimate mean and turbulent properties of the flow. Title: Cohstrex: Coherent Structures in Rivers and Estuaries Experiment Author: Jessup, Andrew, Chickadel, C., Talke, Stefan, Horner-Devine, Alexander Year: 2013 COHSTREX, the Coherent Structures in Rivers and Estuaries Experiment, was a five-year project to exploit the remotely sensed signatures of coherent flow structures in rivers and estuaries. The purpose of the study was to use remote-sensing measurements of coherent structures at a river surface to characterize and quantify the flow. Two major field experiments were undertaken on the Snohomish River near Everett, WA, United States. The first experiment took place near the mouth of the river where stratification was strong due to a tidally driven salt wedge. Flow over a rocky sill generated a field of boils (bottom-generated fluid upwellings) on the flow surface that propagated downstream and provided insight into mixing layer dynamics. The second experiment took place approximately 15[t#]km upstream from the mouth of the river where the tide still affected the river level and velocity, but stratification was minimal. The focus of the unstratified flow experiment was the study of boils generated by flow over flat beds and beds with a bottom roughness. Herein, we provide an overview of infrared measurements of thermal variability on the surface and in-situ measurements of turbulent velocities beneath the surface. A major finding of COHSTREX is that infrared imagery of the thermal signature of coherent flow structures in estuarine rivers is a powerful tool for visualizing and quantifying the flow. Thermal signatures include mixing of water masses with different temperatures, and disruptions of the flow surface by coherent flow structures generated by bottom roughness. Through use of particle image velocimetry (PIV) techniques applied to infrared imagery of the river surface, we are able to estimate mean and turbulent properties of the flow. Close

• 16. [Article] Hydrologic Remote Sensing and Land Surface Data Assimilation

  Accurate, reliable and skillful forecasting of key environmental variables such as soil moisture and snow are of paramount importance due to their strong influence on many water resources applications ...

  Citation × Citation Citation Abstract Copy Title: Hydrologic Remote Sensing and Land Surface Data Assimilation Author: Moradkhani, Hamid Year: 2008 Accurate, reliable and skillful forecasting of key environmental variables such as soil moisture and snow are of paramount importance due to their strong influence on many water resources applications including flood control, agricultural production and effective water resources management which collectively control the behavior of the climate system. Soil moisture is a key state variable in land surface?atmosphere interactions affecting surface energy fluxes, runoff and the radiation balance. Snow processes also have a large influence on land-atmosphere energy exchanges due to snow high albedo, low thermal conductivity and considerable spatial and temporal variability resulting in the dramatic change on surface and ground temperature. Measurement of these two variables is possible through variety of methods using ground-based and remote sensing procedures. Remote sensing, however, holds great promise for soil moisture and snow measurements which have considerable spatial and temporal variability. Merging these measurements with hydrologic model outputs in a systematic and effective way results in an improvement of land surface model prediction. Data Assimilation provides a mechanism to combine these two sources of estimation. Much success has been attained in recent years in using data from passive microwave sensors and assimilating them into the models. This paper provides an overview of the remote sensing measurement techniques for soil moisture and snow data and describes the advances in data assimilation techniques through the ensemble filtering, mainly Ensemble Kalman filter (EnKF) and Particle filter (PF), for improving the model prediction and reducing the uncertainties involved in prediction process. It is believed that PF provides a complete representation of the probability distribution of state variables of interests (according to sequential Bayes law) and could be a strong alternative to EnKF which is subject to some limitations including the linear updating rule and assumption of jointly normal distribution of errors in state variables and observation. Title: Hydrologic Remote Sensing and Land Surface Data Assimilation Author: Moradkhani, Hamid Year: 2008 Accurate, reliable and skillful forecasting of key environmental variables such as soil moisture and snow are of paramount importance due to their strong influence on many water resources applications including flood control, agricultural production and effective water resources management which collectively control the behavior of the climate system. Soil moisture is a key state variable in land surface?atmosphere interactions affecting surface energy fluxes, runoff and the radiation balance. Snow processes also have a large influence on land-atmosphere energy exchanges due to snow high albedo, low thermal conductivity and considerable spatial and temporal variability resulting in the dramatic change on surface and ground temperature. Measurement of these two variables is possible through variety of methods using ground-based and remote sensing procedures. Remote sensing, however, holds great promise for soil moisture and snow measurements which have considerable spatial and temporal variability. Merging these measurements with hydrologic model outputs in a systematic and effective way results in an improvement of land surface model prediction. Data Assimilation provides a mechanism to combine these two sources of estimation. Much success has been attained in recent years in using data from passive microwave sensors and assimilating them into the models. This paper provides an overview of the remote sensing measurement techniques for soil moisture and snow data and describes the advances in data assimilation techniques through the ensemble filtering, mainly Ensemble Kalman filter (EnKF) and Particle filter (PF), for improving the model prediction and reducing the uncertainties involved in prediction process. It is believed that PF provides a complete representation of the probability distribution of state variables of interests (according to sequential Bayes law) and could be a strong alternative to EnKF which is subject to some limitations including the linear updating rule and assumption of jointly normal distribution of errors in state variables and observation. Close

• 17. [Article] 3D Hydrodynamic Model Development and Verification

  A three-dimensional numerical model was developed to simulate hydrodynamic, temperature, and water quality distributions in rivers and lakes. In an attempt to get rid of the extra approximation and complexity, ...

  Citation × Citation Citation Abstract Copy Title: 3D Hydrodynamic Model Development and Verification Author: Al-Zubaidi, Hussein A. M. Year: 2016 A three-dimensional numerical model was developed to simulate hydrodynamic, temperature, and water quality distributions in rivers and lakes. In an attempt to get rid of the extra approximation and complexity, no coordinate transformation has been done and z-coordinate system has been employed. The governing equations are the continuity equation, free surface equation, momentum equations, and conservation equations of temperature and water quality. The model employs the time splitting technique which allows splitting the directions in which we end with two-dimensional governing equations and eventually the solution ends with a tri-diagonal matrix, which is easily solved by Thomas algorithm. The first step after developing a numerical model and before adding more features or applying the model to a real case, the model should be verified. The verification of the model was done by implementing the model to known solutions test cases in additional to evaluating whether the code preserves fluid mass. A series of test cases is performed by comparing the model results with the analytical solutions as proposed by many modelers. The model showed good agreement between the analytical and the numerical solution. Title: 3D Hydrodynamic Model Development and Verification Author: Al-Zubaidi, Hussein A. M. Year: 2016 A three-dimensional numerical model was developed to simulate hydrodynamic, temperature, and water quality distributions in rivers and lakes. In an attempt to get rid of the extra approximation and complexity, no coordinate transformation has been done and z-coordinate system has been employed. The governing equations are the continuity equation, free surface equation, momentum equations, and conservation equations of temperature and water quality. The model employs the time splitting technique which allows splitting the directions in which we end with two-dimensional governing equations and eventually the solution ends with a tri-diagonal matrix, which is easily solved by Thomas algorithm. The first step after developing a numerical model and before adding more features or applying the model to a real case, the model should be verified. The verification of the model was done by implementing the model to known solutions test cases in additional to evaluating whether the code preserves fluid mass. A series of test cases is performed by comparing the model results with the analytical solutions as proposed by many modelers. The model showed good agreement between the analytical and the numerical solution. Close

• 18. [Article] Lake Whatcom Water Quality Model

  A water quality model of Lake Whatcom, Washington was developed as part of a Total Maximum Daily Load Study for the Washington Department of Ecology. Lake Whatcom is a large natural lake which is listed ...

  Citation × Citation Citation Abstract Copy Title: Lake Whatcom Water Quality Model Author: Berger, Chris Year: 2005 A water quality model of Lake Whatcom, Washington was developed as part of a Total Maximum Daily Load Study for the Washington Department of Ecology. Lake Whatcom is a large natural lake which is listed on the 1998 Washington State 303(d) list of waterbodies which do not meet the criterion for dissolved oxygen. Located next to the city of Bellingham, it is approximately 10 miles long and has a surface area of approximately 5000 acres and a maximum depth of over 100 meters. Eutrophication processes in the lake have been accelerated in recent years perhaps by the availability of nutrients from tributary discharges to the basin. Many of these tributaries have accelerated their nutrient loading to the system as a result of development in the watershed. The lake is being modeled using the Corps of Engineer’s model CE-QUAL-W2, which is a two-dimensional, hydrodynamic and water quality model. The project is managed by the Washington Department of Ecology which plans to make recommendations for reduction and allocation of pollutant loads. The objectives of this study were then to develop a hydrodynamic and water quality model of Lake Whatcom, calibrate the model to field data collected from February 2002 through December 2003, and use the model to evaluate strategies for water quality improvement. Title: Lake Whatcom Water Quality Model Author: Berger, Chris Year: 2005 A water quality model of Lake Whatcom, Washington was developed as part of a Total Maximum Daily Load Study for the Washington Department of Ecology. Lake Whatcom is a large natural lake which is listed on the 1998 Washington State 303(d) list of waterbodies which do not meet the criterion for dissolved oxygen. Located next to the city of Bellingham, it is approximately 10 miles long and has a surface area of approximately 5000 acres and a maximum depth of over 100 meters. Eutrophication processes in the lake have been accelerated in recent years perhaps by the availability of nutrients from tributary discharges to the basin. Many of these tributaries have accelerated their nutrient loading to the system as a result of development in the watershed. The lake is being modeled using the Corps of Engineer’s model CE-QUAL-W2, which is a two-dimensional, hydrodynamic and water quality model. The project is managed by the Washington Department of Ecology which plans to make recommendations for reduction and allocation of pollutant loads. The objectives of this study were then to develop a hydrodynamic and water quality model of Lake Whatcom, calibrate the model to field data collected from February 2002 through December 2003, and use the model to evaluate strategies for water quality improvement. Close

• 19. [Article] Observations at the Tidal Plume Front of a High-Volume River Outflow

  We present shipboard observations of very strong convergence, vertical velocities and mixing, and near-bed impacts associated with the leading-edge front of the tidally-pulsed Columbia River plume. With ...

  Citation × Citation Citation Abstract Copy Title: Observations at the Tidal Plume Front of a High-Volume River Outflow Author: Orton, Philip M., Jay, David A. Year: 2005 We present shipboard observations of very strong convergence, vertical velocities and mixing, and near-bed impacts associated with the leading-edge front of the tidally-pulsed Columbia River plume. With upwelling-favorable winds and riverflow of 4900 m3s−1, the plume propagates as a buoyant gravity current with a rotary, bore-like vertical frontal circulation and downwelling as strong as 0.35 m s−1. In waters as deep as 65 m, near-bed currents intensify to as much as 1.0 m s−1 after frontal passage, and are often associated with elevated acoustic backscatter. Mixing is locally strong, with an eddy diffusivity of O(0.2 m2s−1) 50 m behind the front, and T-S diagrams imply plume mixing with 10 m deep ocean water. These observations indicate that the leading-edge front of a surface-advected plume can cause exchanges of (a) nutrients between cold subsurface shelf waters and the river plume, and (b) nutrients and sediments across the sediment-water interface. Title: Observations at the Tidal Plume Front of a High-Volume River Outflow Author: Orton, Philip M., Jay, David A. Year: 2005 We present shipboard observations of very strong convergence, vertical velocities and mixing, and near-bed impacts associated with the leading-edge front of the tidally-pulsed Columbia River plume. With upwelling-favorable winds and riverflow of 4900 m3s−1, the plume propagates as a buoyant gravity current with a rotary, bore-like vertical frontal circulation and downwelling as strong as 0.35 m s−1. In waters as deep as 65 m, near-bed currents intensify to as much as 1.0 m s−1 after frontal passage, and are often associated with elevated acoustic backscatter. Mixing is locally strong, with an eddy diffusivity of O(0.2 m2s−1) 50 m behind the front, and T-S diagrams imply plume mixing with 10 m deep ocean water. These observations indicate that the leading-edge front of a surface-advected plume can cause exchanges of (a) nutrients between cold subsurface shelf waters and the river plume, and (b) nutrients and sediments across the sediment-water interface. Close

• 20. [Article] Evaluating the Performance of Contech’s StormFilter with ZPG Media Under the City of Portland’s 2016 Stormwater Management Manual Requirements for Manufactured Stormwater Treatment Technologies

  Stormwater runoff is the water generated from excess rainfall or snowmelt that flows over impervious surfaces such as paved roads, parking lots, and on roofs, it often carries a variety of pollutants that ...

  Citation × Citation Citation Abstract Copy Title: Evaluating the Performance of Contech’s StormFilter with ZPG Media Under the City of Portland’s 2016 Stormwater Management Manual Requirements for Manufactured Stormwater Treatment Technologies Author: Khammas, Mawj TH Year: 2017 Stormwater runoff is the water generated from excess rainfall or snowmelt that flows over impervious surfaces such as paved roads, parking lots, and on roofs, it often carries a variety of pollutants that adversely affect water quality in that region. Portland is a well-developed city; the majority of the streets are paved and impervious and will consequently generate a tremendous amount of stormwater this creates the necessity for management to help preserve and mimic natural hydrologic cycle through improving water quality. The StormFilter® with ZPG media, manufactured by CONTECH, is a manufactured stormwater treatment technology(MSTT) in which zeolite, perlite, and granular activated carbon are used. The device has a current Routine Use Level Designation (GULD) for basic treatment from the Washington State Department of Ecology (WA DOE) under the Technology Assessment Protocol-Ecology (TAPE). Storm data from two different sites were used to evaluate the performance of The StormFilter-ZPG with respect to Portland’s pollution reduction requirements, as prescribed in the 2016 Stormwater Management Manual (SWMM). The results of the evaluation suggest approving the device for use in the City of Portland at the TAPE-approved flow rate of 1 gpm/ft². Title: Evaluating the Performance of Contech’s StormFilter with ZPG Media Under the City of Portland’s 2016 Stormwater Management Manual Requirements for Manufactured Stormwater Treatment Technologies Author: Khammas, Mawj TH Year: 2017 Stormwater runoff is the water generated from excess rainfall or snowmelt that flows over impervious surfaces such as paved roads, parking lots, and on roofs, it often carries a variety of pollutants that adversely affect water quality in that region. Portland is a well-developed city; the majority of the streets are paved and impervious and will consequently generate a tremendous amount of stormwater this creates the necessity for management to help preserve and mimic natural hydrologic cycle through improving water quality. The StormFilter® with ZPG media, manufactured by CONTECH, is a manufactured stormwater treatment technology(MSTT) in which zeolite, perlite, and granular activated carbon are used. The device has a current Routine Use Level Designation (GULD) for basic treatment from the Washington State Department of Ecology (WA DOE) under the Technology Assessment Protocol-Ecology (TAPE). Storm data from two different sites were used to evaluate the performance of The StormFilter-ZPG with respect to Portland’s pollution reduction requirements, as prescribed in the 2016 Stormwater Management Manual (SWMM). The results of the evaluation suggest approving the device for use in the City of Portland at the TAPE-approved flow rate of 1 gpm/ft². Close

• 21. [Article] Impacts of Columbia River Discharge on Salmonid Habitat: 2. Changes in Shallow-Water Habitat

  This is the second part of an investigation that analyzes human alteration of shallow-water habitat (SWH) available to juvenile salmonids in the tidal Lower Columbia River. Part 2 develops a one-dimensional, ...

  Citation × Citation Citation Abstract Copy Title: Impacts of Columbia River Discharge on Salmonid Habitat: 2. Changes in Shallow-Water Habitat Author: Jay, David A., Kukulka, Tobias Year: 2003 This is the second part of an investigation that analyzes human alteration of shallow-water habitat (SWH) available to juvenile salmonids in the tidal Lower Columbia River. Part 2 develops a one-dimensional, subtidal river stage model that explains ~90% of the stage variance in the tidal river. This model and the tidal model developed in part 1 (Kukulka and Jay, 2003) uncouple the nonlinear interaction of river tides and river stage by referring both to external forcing by river discharge, ocean tides, and atmospheric pressure. Applying the two models, daily high-water levels were predicted for a reach from rkm-50 to rkm-90 during 1974 to 1998, the period of contemporary management. Predicted water levels were related to the bathymetry and topography to determine the changes in shallow-water habitat area (SWHA) caused by flood control dikes and altered flow management. Model results suggest that diking and a >40% reduction of peak flows have reduced SWHA by ~62% during the crucial spring freshet period during which juvenile salmon use of SWHA is maximal. Taken individually, diking and flow cycle alteration reduced spring freshet SWHA by 52% and 29%, respectively. SWHA has been both displaced to lower elevations and modified in its character because tidal range has increased. Our models of these processes are economical for the very long simulations (seasons to centuries) needed to understand historic changes and climate impacts on SWH. Through analysis of the nonlinear processes controlling surface elevation in a tidal river, we have identified some of the mechanisms that link freshwater discharge to SWH and salmonid survival. Title: Impacts of Columbia River Discharge on Salmonid Habitat: 2. Changes in Shallow-Water Habitat Author: Jay, David A., Kukulka, Tobias Year: 2003 This is the second part of an investigation that analyzes human alteration of shallow-water habitat (SWH) available to juvenile salmonids in the tidal Lower Columbia River. Part 2 develops a one-dimensional, subtidal river stage model that explains ~90% of the stage variance in the tidal river. This model and the tidal model developed in part 1 (Kukulka and Jay, 2003) uncouple the nonlinear interaction of river tides and river stage by referring both to external forcing by river discharge, ocean tides, and atmospheric pressure. Applying the two models, daily high-water levels were predicted for a reach from rkm-50 to rkm-90 during 1974 to 1998, the period of contemporary management. Predicted water levels were related to the bathymetry and topography to determine the changes in shallow-water habitat area (SWHA) caused by flood control dikes and altered flow management. Model results suggest that diking and a >40% reduction of peak flows have reduced SWHA by ~62% during the crucial spring freshet period during which juvenile salmon use of SWHA is maximal. Taken individually, diking and flow cycle alteration reduced spring freshet SWHA by 52% and 29%, respectively. SWHA has been both displaced to lower elevations and modified in its character because tidal range has increased. Our models of these processes are economical for the very long simulations (seasons to centuries) needed to understand historic changes and climate impacts on SWH. Through analysis of the nonlinear processes controlling surface elevation in a tidal river, we have identified some of the mechanisms that link freshwater discharge to SWH and salmonid survival. Close

• 22. [Article] A Multi-Class Suspended Particulate Matter Calibration for Bottom Boundary Layers

  We present a multi-class suspended particulate matter (SPM) calibration for use with in situ water sample SPM concentration data and backscatter (or transmission) from one or more acoustic and optical ...

  Citation × Citation Citation Abstract Copy Title: A Multi-Class Suspended Particulate Matter Calibration for Bottom Boundary Layers Author: Orton, Philip M., Jay, David A., Wilson, D. J. Year: 2003 We present a multi-class suspended particulate matter (SPM) calibration for use with in situ water sample SPM concentration data and backscatter (or transmission) from one or more acoustic and optical sensors. The output of this calibration is high-resolution SPM concentration data in several discrete settling velocity (Ws) classes. Separately for each sensor, the calibration involves three steps: (1) a calibration of backscatter to total SPM concentration; (2) a decomposition of resulting concentration data into several Wsclasses, utilizing a dynamical vertical SPM profile model; and (3) a sensor bias calibration where water sample concentration data are used to correct for the sediment size-dependence of sensor response. Multiple sensors can be incorporated to improve the results, as step 3 can objectively choose the best sensor for monitoring each Ws-class. The calibration is generally applicable in wave-current boundary layers, though this paper is focused on currents only. We demonstrate the method using data from greater-ebb SPM export events in the Fraser River estuary, when salt has washed out beyond the river entrance, surface currents are strong (3+ m s??) and turbulent mixing is intense. The resulting concentration estimates show good agreement with in situ particle-size observations near the bed, but discrepancies increasing with height above the bed, likely due to violation of model assumptions in the outer part of the water column. An uncertainty analysis indicates that the standard deviation in concentration estimates is 32-48%, primarily due to poor near-bed acoustic data coverage and uncertainty in water sample concentration data. We conclude by discussing planned improvements for strongly advective and aggregate-dominated systems. Title: A Multi-Class Suspended Particulate Matter Calibration for Bottom Boundary Layers Author: Orton, Philip M., Jay, David A., Wilson, D. J. Year: 2003 We present a multi-class suspended particulate matter (SPM) calibration for use with in situ water sample SPM concentration data and backscatter (or transmission) from one or more acoustic and optical sensors. The output of this calibration is high-resolution SPM concentration data in several discrete settling velocity (Ws) classes. Separately for each sensor, the calibration involves three steps: (1) a calibration of backscatter to total SPM concentration; (2) a decomposition of resulting concentration data into several Wsclasses, utilizing a dynamical vertical SPM profile model; and (3) a sensor bias calibration where water sample concentration data are used to correct for the sediment size-dependence of sensor response. Multiple sensors can be incorporated to improve the results, as step 3 can objectively choose the best sensor for monitoring each Ws-class. The calibration is generally applicable in wave-current boundary layers, though this paper is focused on currents only. We demonstrate the method using data from greater-ebb SPM export events in the Fraser River estuary, when salt has washed out beyond the river entrance, surface currents are strong (3+ m s??) and turbulent mixing is intense. The resulting concentration estimates show good agreement with in situ particle-size observations near the bed, but discrepancies increasing with height above the bed, likely due to violation of model assumptions in the outer part of the water column. An uncertainty analysis indicates that the standard deviation in concentration estimates is 32-48%, primarily due to poor near-bed acoustic data coverage and uncertainty in water sample concentration data. We conclude by discussing planned improvements for strongly advective and aggregate-dominated systems. Close

• 23. [Article] The Columbia River Plume Study: Subtidal Variability in the Velocity and Salinity Fields

  A comprehensive study of the strongly wind driven midlatitude buoyant plume from the Columbia River, located on the U.S. west coast, demonstrates that the plume has two basic structures during the fall/winter ...

  Citation × Citation Citation Abstract Copy Title: The Columbia River Plume Study: Subtidal Variability in the Velocity and Salinity Fields Author: Hickey, B. M., Pietrafesa, Leonard J., Jay, David A., Boicourt, William C. Year: 1998 A comprehensive study of the strongly wind driven midlatitude buoyant plume from the Columbia River, located on the U.S. west coast, demonstrates that the plume has two basic structures during the fall/winter season, namely, a thin (~5~15 m), strongly stratified plume tending west to northwestward during periods of southward or light northward wind stress and a thicker (~10~40 m), weakly stratified plume tending northward and hugging the coast during periods of stronger northward stress. The plume and its velocity field respond nearly instantaneously to changes in wind speed or direction, and the wind fluctuations have timescales of 2-10 days. Frictional wind-driven currents cause the primarily unidirectional flow down the plume axis to veer to the right or left of the axis for northward or southward winds, respectively. Farther downstream, currents turn to parallel rather than cross salinity contours, consistent with a geostrophic balance. In particular, during periods when the plume is separated from the coast, currents tend to flow around the mound of fresher water. At distances exceeding about 20 km from the river mouth, the along-shelf depth-averaged flow over the inner to midshelf is linear, and depth-averaged acceleration is governed to lowest order by the difference between surface and bottom stress alone. In this region, along-shelf geostrophic buoyancy-driven currents at ~5 m (calculated from surface density) and along-shelf geostrophic wind-driven currents (computed from a depth-averaged linear model) are comparable in magnitude (~10-25 cm-1 ). Title: The Columbia River Plume Study: Subtidal Variability in the Velocity and Salinity Fields Author: Hickey, B. M., Pietrafesa, Leonard J., Jay, David A., Boicourt, William C. Year: 1998 A comprehensive study of the strongly wind driven midlatitude buoyant plume from the Columbia River, located on the U.S. west coast, demonstrates that the plume has two basic structures during the fall/winter season, namely, a thin (~5~15 m), strongly stratified plume tending west to northwestward during periods of southward or light northward wind stress and a thicker (~10~40 m), weakly stratified plume tending northward and hugging the coast during periods of stronger northward stress. The plume and its velocity field respond nearly instantaneously to changes in wind speed or direction, and the wind fluctuations have timescales of 2-10 days. Frictional wind-driven currents cause the primarily unidirectional flow down the plume axis to veer to the right or left of the axis for northward or southward winds, respectively. Farther downstream, currents turn to parallel rather than cross salinity contours, consistent with a geostrophic balance. In particular, during periods when the plume is separated from the coast, currents tend to flow around the mound of fresher water. At distances exceeding about 20 km from the river mouth, the along-shelf depth-averaged flow over the inner to midshelf is linear, and depth-averaged acceleration is governed to lowest order by the difference between surface and bottom stress alone. In this region, along-shelf geostrophic buoyancy-driven currents at ~5 m (calculated from surface density) and along-shelf geostrophic wind-driven currents (computed from a depth-averaged linear model) are comparable in magnitude (~10-25 cm-1 ). Close

• 24. [Article] Improving Soil Moisture Profile Prediction With the Particle Filter-Markov Chain Monte Carlo Method

  Satellite soil moisture estimates have received increasing attention over the past decade. This paper examines the applicability of estimating soil moisture states and soil hydraulic parameters through ...

  Citation × Citation Citation Abstract Copy Title: Improving Soil Moisture Profile Prediction With the Particle Filter-Markov Chain Monte Carlo Method Author: Yan, Hongxiang, DeChant, Caleb Matthew, Moradkhani, Hamid Year: 2015 Satellite soil moisture estimates have received increasing attention over the past decade. This paper examines the applicability of estimating soil moisture states and soil hydraulic parameters through two particle filter (PF) methods: The PF with commonly used sampling importance resampling (PF-SIR) and the PF with recently developed Markov chain Monte Carlo sampling (PF-MCMC) methods. In a synthetic experiment, the potential of assimilating remotely sensed near-surface soil moisture measurements into a 1-D mechanistic soil water model (HYDRUS-1D) using both the PF-SIR and PF-MCMC algorithms is analyzed. The effects of satellite temporal resolution and accuracy, soil type, and ensemble size on the assimilation of soil moisture are analyzed. In a real data experiment, we first validate the Advanced Microwave Scanning Radiometer--Earth Observing System (AMSR-E) soil moisture products in the Oklahoma Little Washita Watershed. Aside from rescaling the remotely sensed soil moisture, a bias correction algorithm is implemented to correct the deep soil moisture estimate. Both the ascending and descending AMSR-E soil moisture data are assimilated into the HYDRUS-1D model. The synthetic assimilation results indicated that, whereas both updating schemes showed the ability to correct the soil moisture state and estimate hydraulic parameters, the PF-MCMC scheme is consistently more accurate than PR-SIR. For real data case, the quality of remotely sensed soil moisture impacts the benefits of their assimilation into the model. The PF-MCMC scheme brought marginal gains than the open-loop simulation in RMSE at both surface and root-zone soil layer, whereas the PF-SIR scheme degraded the open-loop simulation. Title: Improving Soil Moisture Profile Prediction With the Particle Filter-Markov Chain Monte Carlo Method Author: Yan, Hongxiang, DeChant, Caleb Matthew, Moradkhani, Hamid Year: 2015 Satellite soil moisture estimates have received increasing attention over the past decade. This paper examines the applicability of estimating soil moisture states and soil hydraulic parameters through two particle filter (PF) methods: The PF with commonly used sampling importance resampling (PF-SIR) and the PF with recently developed Markov chain Monte Carlo sampling (PF-MCMC) methods. In a synthetic experiment, the potential of assimilating remotely sensed near-surface soil moisture measurements into a 1-D mechanistic soil water model (HYDRUS-1D) using both the PF-SIR and PF-MCMC algorithms is analyzed. The effects of satellite temporal resolution and accuracy, soil type, and ensemble size on the assimilation of soil moisture are analyzed. In a real data experiment, we first validate the Advanced Microwave Scanning Radiometer--Earth Observing System (AMSR-E) soil moisture products in the Oklahoma Little Washita Watershed. Aside from rescaling the remotely sensed soil moisture, a bias correction algorithm is implemented to correct the deep soil moisture estimate. Both the ascending and descending AMSR-E soil moisture data are assimilated into the HYDRUS-1D model. The synthetic assimilation results indicated that, whereas both updating schemes showed the ability to correct the soil moisture state and estimate hydraulic parameters, the PF-MCMC scheme is consistently more accurate than PR-SIR. For real data case, the quality of remotely sensed soil moisture impacts the benefits of their assimilation into the model. The PF-MCMC scheme brought marginal gains than the open-loop simulation in RMSE at both surface and root-zone soil layer, whereas the PF-SIR scheme degraded the open-loop simulation. Close

• 25. [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

• 26. [Article] Decadal-Scale Changes in West Coast Shelf Internal Tides (the Tides, They are a Changin')

  The National Science Foundation (NSF) Co-OP (Coastal Ocean Program) Project RISE (River-Influenced Shelf Ecosystems) seeks to understand how primary and secondary productivity are enhanced by large river ...

  Citation × Citation Citation Abstract Copy Title: Decadal-Scale Changes in West Coast Shelf Internal Tides (the Tides, They are a Changin') Author: Jay, David A., Chisholm, Thomas A., Krause, A., Leffler, K. Year: 2004 The National Science Foundation (NSF) Co-OP (Coastal Ocean Program) Project RISE (River-Influenced Shelf Ecosystems) seeks to understand how primary and secondary productivity are enhanced by large river plumes in upwelling regions, using the Columbia River plume as a case study. Columbia River plume waters are rich in silicate and iron, but relatively depleted in nitrate. Mixing of nitrate-rich upwelled water with the plume is, therefore, important to plume primary production. Large internal tidal currents cause part of the necessary mixing. Accordingly, any long-term changes in these internal tides could impact productivity. Because no decadal-scale current observations are available to evaluate changes in internal tides, an indirect approach is needed ? we examine long-term changes in the surface tide (which is affected by internal tides) relative to the astronomical tidal potential. Of course, observed tides are affected by human manipulation of coastal environments as well as by changes in internal tides. Thus, four methods were used to separate estuarine human and coastal effects on observed surface tides: (A) Examination of historical changes in tidal admittance along the West Coast using long-term tide stations between 16ø and 60.5ø N; 14 million hourly tidal heights for 1854 to 2004 were analyzed. These stations show a broad range of human impacts, but most show increasing tides. (B) Use of tidal constituent ratios to diagnose processes; e.g., a channelization-induced reduction in estuarine friction affects the S?/M? ratio, while a decrease in K1/M? may indicate the changing influence of internal tides, at least north of 30ø N. (C) Examination of the spatial pattern of tidal properties in the three major West Coast shallow estuaries for which multiple stations with long records are available (San Diego and San Francisco Bays and the Columbia). (D) Analysis of seasonal patterns in tidal admittance relative to river flow and sea level in the Columbia, to separate fluvial and shelf processes. Title: Decadal-Scale Changes in West Coast Shelf Internal Tides (the Tides, They are a Changin') Author: Jay, David A., Chisholm, Thomas A., Krause, A., Leffler, K. Year: 2004 The National Science Foundation (NSF) Co-OP (Coastal Ocean Program) Project RISE (River-Influenced Shelf Ecosystems) seeks to understand how primary and secondary productivity are enhanced by large river plumes in upwelling regions, using the Columbia River plume as a case study. Columbia River plume waters are rich in silicate and iron, but relatively depleted in nitrate. Mixing of nitrate-rich upwelled water with the plume is, therefore, important to plume primary production. Large internal tidal currents cause part of the necessary mixing. Accordingly, any long-term changes in these internal tides could impact productivity. Because no decadal-scale current observations are available to evaluate changes in internal tides, an indirect approach is needed ? we examine long-term changes in the surface tide (which is affected by internal tides) relative to the astronomical tidal potential. Of course, observed tides are affected by human manipulation of coastal environments as well as by changes in internal tides. Thus, four methods were used to separate estuarine human and coastal effects on observed surface tides: (A) Examination of historical changes in tidal admittance along the West Coast using long-term tide stations between 16ø and 60.5ø N; 14 million hourly tidal heights for 1854 to 2004 were analyzed. These stations show a broad range of human impacts, but most show increasing tides. (B) Use of tidal constituent ratios to diagnose processes; e.g., a channelization-induced reduction in estuarine friction affects the S?/M? ratio, while a decrease in K1/M? may indicate the changing influence of internal tides, at least north of 30ø N. (C) Examination of the spatial pattern of tidal properties in the three major West Coast shallow estuaries for which multiple stations with long records are available (San Diego and San Francisco Bays and the Columbia). (D) Analysis of seasonal patterns in tidal admittance relative to river flow and sea level in the Columbia, to separate fluvial and shelf processes. Close

• 27. [Article] Modeling Effects of Channel Complexity and Hyporheic Flow on Stream Temperatures

  Stream temperatures are affected by multiple forcing functions, including surface heat exchange (including solar radiation, evaporation, conduction, and net long wave radiation) and hyporheic flows. Each ...

  Citation × Citation Citation Abstract Copy Title: Modeling Effects of Channel Complexity and Hyporheic Flow on Stream Temperatures Author: Berger, Chris, Wells, Scott A. Year: 2007 Stream temperatures are affected by multiple forcing functions, including surface heat exchange (including solar radiation, evaporation, conduction, and net long wave radiation) and hyporheic flows. Each of these forcing functions is directly influenced by the level of channel complexity in the stream channel and riparian shading. The interrelationship between channel complexity, hyporheic flow and stream temperature is highly complex, and efforts to manage for habitat diversity by managing channel complexity could result in unintended consequences on stream temperature. When planning modifications to stream channel complexity, consideration should be given to the effects such moderations could have on stream temperatures. Urbanization has impacted many steams due to the construction of bank protections, levees, vegetation removal, etc. Such activities have eliminated side channels and reduced stream braiding, thereby reducing the overall channel complexity. Hulse et al. (2002) developed maps showing the channel configurations of the Willamette River in Oregon, USA in the years 1850 and 1995. These maps show a significant reduction in channel complexity in the intervening years. More complex stream channels provide greater habitat diversity and thus, are generally more desirable from a wildlife management perspective. Therefore, management of streams for increased channel complexity is gaining in popularity. Knowing that stream channel complexity has diminished over time, an important question to consider is ‘what were stream temperatures before we altered the natural channels?’ This is an important issue in determining what natural conditions were and how we have strayed from these so-called ‘natural’ conditions as a result of channelization, dam building, and changes to the riparian vegetation and deforestation. Current Total Maximum Daily Load’s (TMDL) rely on determining a ‘natural’ condition. In order to develop an understanding of what that is, a hydrodynamic and water quality computer simulation model has been applied to Oregon’s Willamette River with several levels of channel complexity and varying rates of hyporheic flows. Adapting the model used to develop TMDL’s for temperature in the Willamette River, the effects of present and past channel complexity on water temperatures was determined. The model used to develop the TMDL was the U. S. Army Corps of Engineers dynamic 2-D model CE-QUAL-W2, which consists of directly coupled hydrodynamic and water quality transport models and simulates parameters such as temperature, algae concentration, dissolved oxygen concentration, pH, nutrient concentrations and residence time. The model also incorporates a dynamic shading algorithm for both vegetative and topographic shading on water bodies. Title: Modeling Effects of Channel Complexity and Hyporheic Flow on Stream Temperatures Author: Berger, Chris, Wells, Scott A. Year: 2007 Stream temperatures are affected by multiple forcing functions, including surface heat exchange (including solar radiation, evaporation, conduction, and net long wave radiation) and hyporheic flows. Each of these forcing functions is directly influenced by the level of channel complexity in the stream channel and riparian shading. The interrelationship between channel complexity, hyporheic flow and stream temperature is highly complex, and efforts to manage for habitat diversity by managing channel complexity could result in unintended consequences on stream temperature. When planning modifications to stream channel complexity, consideration should be given to the effects such moderations could have on stream temperatures. Urbanization has impacted many steams due to the construction of bank protections, levees, vegetation removal, etc. Such activities have eliminated side channels and reduced stream braiding, thereby reducing the overall channel complexity. Hulse et al. (2002) developed maps showing the channel configurations of the Willamette River in Oregon, USA in the years 1850 and 1995. These maps show a significant reduction in channel complexity in the intervening years. More complex stream channels provide greater habitat diversity and thus, are generally more desirable from a wildlife management perspective. Therefore, management of streams for increased channel complexity is gaining in popularity. Knowing that stream channel complexity has diminished over time, an important question to consider is ‘what were stream temperatures before we altered the natural channels?’ This is an important issue in determining what natural conditions were and how we have strayed from these so-called ‘natural’ conditions as a result of channelization, dam building, and changes to the riparian vegetation and deforestation. Current Total Maximum Daily Load’s (TMDL) rely on determining a ‘natural’ condition. In order to develop an understanding of what that is, a hydrodynamic and water quality computer simulation model has been applied to Oregon’s Willamette River with several levels of channel complexity and varying rates of hyporheic flows. Adapting the model used to develop TMDL’s for temperature in the Willamette River, the effects of present and past channel complexity on water temperatures was determined. The model used to develop the TMDL was the U. S. Army Corps of Engineers dynamic 2-D model CE-QUAL-W2, which consists of directly coupled hydrodynamic and water quality transport models and simulates parameters such as temperature, algae concentration, dissolved oxygen concentration, pH, nutrient concentrations and residence time. The model also incorporates a dynamic shading algorithm for both vegetative and topographic shading on water bodies. Close

• 28. [Article] New Insights into the Controls and Mechanisms of Plankton Productivity Along the US West Coast

  During the lifetime of the National Science Foundation's Coastal Ocean Processes program, four experiments were conducted on the US West Coast in the northern California Current System. Although each project ...

  Citation × Citation Citation Abstract Copy Title: New Insights into the Controls and Mechanisms of Plankton Productivity Along the US West Coast Author: Kudela, Raphael M., Banas, Neil S., Barth, John A., Frame, Elizabeth R., Jay, David A., Largier, John L., Lessard, Evelyn J., Peterson, Tawnya D., Vander Woude, Andrea J. Year: 2008 During the lifetime of the National Science Foundation's Coastal Ocean Processes program, four experiments were conducted on the US West Coast in the northern California Current System. Although each project had a unique scientific focus, all four addressed the mechanisms causing eastern boundary current systems in general, and the California Current System in particular, to be biologically rich, from phytoplankton to apex predators. Taken together, findings from these projects provide new insights into the canonical view that upwelling systems are simple wind-driven "conveyor belts," bringing cold, nutrient-rich waters to the well-lit surface ocean where biological organisms flourish. We highlight new insights and advances gained from these programs, including recognition that (a) elements other than nitrogen, particularly iron, may limit the base of the food chain, and (b) the source of these nutrients is not solely a result of wind-driven Ekman transport. The importance of retentive features has clearly emerged, whether these are associated with topography, bathymetry, or more transient features such as river plumes. These new insights into the drivers and fate of this high biological productivity should greatly improve current and future generations of ecosystem models and provide a better understanding of the unique physical-biological coupling that makes the California Current System so rich. Title: New Insights into the Controls and Mechanisms of Plankton Productivity Along the US West Coast Author: Kudela, Raphael M., Banas, Neil S., Barth, John A., Frame, Elizabeth R., Jay, David A., Largier, John L., Lessard, Evelyn J., Peterson, Tawnya D., Vander Woude, Andrea J. Year: 2008 During the lifetime of the National Science Foundation's Coastal Ocean Processes program, four experiments were conducted on the US West Coast in the northern California Current System. Although each project had a unique scientific focus, all four addressed the mechanisms causing eastern boundary current systems in general, and the California Current System in particular, to be biologically rich, from phytoplankton to apex predators. Taken together, findings from these projects provide new insights into the canonical view that upwelling systems are simple wind-driven "conveyor belts," bringing cold, nutrient-rich waters to the well-lit surface ocean where biological organisms flourish. We highlight new insights and advances gained from these programs, including recognition that (a) elements other than nitrogen, particularly iron, may limit the base of the food chain, and (b) the source of these nutrients is not solely a result of wind-driven Ekman transport. The importance of retentive features has clearly emerged, whether these are associated with topography, bathymetry, or more transient features such as river plumes. These new insights into the drivers and fate of this high biological productivity should greatly improve current and future generations of ecosystem models and provide a better understanding of the unique physical-biological coupling that makes the California Current System so rich. Close

• 29. [Article] Estimating Open-Ocean Barotropic Tidal Dissipation: The Hawaiian Ridge

  The generalized inverse of a regional model is used to estimate barotropic tidal dissipation along the Hawaiian Ridge. The model, based on the linear shallow-water equations, incorporates parameterizations ...

  Citation × Citation Citation Abstract Copy Title: Estimating Open-Ocean Barotropic Tidal Dissipation: The Hawaiian Ridge Author: Zaron, Edward D., Egbert, Gary D. Year: 2006 The generalized inverse of a regional model is used to estimate barotropic tidal dissipation along the Hawaiian Ridge. The model, based on the linear shallow-water equations, incorporates parameterizations for the dissipation of energy via friction in the bottom boundary layer and form drag due to internal waves generated at topographic slopes. Sea surface height data from 364 orbit cycles of the Ocean Topography Experiment (TOPEX)/Poseidon satellite mission are used to perform inversions at eight diurnal and semidiurnal tidal frequencies. It is estimated that the barotropic M2 tide loses energy at a rate of 19 GW, of which 88% is lost within 250 km of the ridge, presumably via conversion to the internal or baroclinic tide. Uncertainty in the assumed model error and wave drag in the forward model suggest that M? dissipation values from 18 to 25 GW are consistent with the altimetric observations. Other barotropic tidal constituents are estimated to lose a total of 5.7 GW. The spatial distribution of barotropic dissipation along the ridge is similar to that inferred from three-dimensional primitive equation models, and it is largely insensitive to details of assumed model and data errors. Dissipation at semidiurnal frequencies is most intense at the French Frigate Shoals with lesser, but significant, contributions at other sites. Diurnal tidal dissipation is concentrated to the east of the French Frigate Shoals, at the Gardner Pinnacles. Further work with three-dimensional models will be necessary to determine the fate of the energy that is removed from the barotropic tide. Title: Estimating Open-Ocean Barotropic Tidal Dissipation: The Hawaiian Ridge Author: Zaron, Edward D., Egbert, Gary D. Year: 2006 The generalized inverse of a regional model is used to estimate barotropic tidal dissipation along the Hawaiian Ridge. The model, based on the linear shallow-water equations, incorporates parameterizations for the dissipation of energy via friction in the bottom boundary layer and form drag due to internal waves generated at topographic slopes. Sea surface height data from 364 orbit cycles of the Ocean Topography Experiment (TOPEX)/Poseidon satellite mission are used to perform inversions at eight diurnal and semidiurnal tidal frequencies. It is estimated that the barotropic M2 tide loses energy at a rate of 19 GW, of which 88% is lost within 250 km of the ridge, presumably via conversion to the internal or baroclinic tide. Uncertainty in the assumed model error and wave drag in the forward model suggest that M? dissipation values from 18 to 25 GW are consistent with the altimetric observations. Other barotropic tidal constituents are estimated to lose a total of 5.7 GW. The spatial distribution of barotropic dissipation along the ridge is similar to that inferred from three-dimensional primitive equation models, and it is largely insensitive to details of assumed model and data errors. Dissipation at semidiurnal frequencies is most intense at the French Frigate Shoals with lesser, but significant, contributions at other sites. Diurnal tidal dissipation is concentrated to the east of the French Frigate Shoals, at the Gardner Pinnacles. Further work with three-dimensional models will be necessary to determine the fate of the energy that is removed from the barotropic tide. Close

• 30. [Article] Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface Bonded Carbon Fiber-Reinforced Polymer

  This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for ...

  Citation × Citation Citation Abstract Copy Title: Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface Bonded Carbon Fiber-Reinforced Polymer Author: Higgins, Christopher, Dawson, Matthew R., Mitchell, Mikal M., Sopal, Gautam, Senturk, A. Ekin Year: 2009 This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort included determining the role of freeze-thaw, moisture, and fatigue on structural performance and developing analytical design procedures that account for durability. The results showed that moisture infiltration behind the CFRP, combined with freeze-thaw, was critical in reducing shear panel stiffness and shear capacity. Long-term moisture exposure alone produced only a minor decrease in shear capacity. Freeze-thaw, combined with fatigue, had little effect on shear capacity if water infiltration was minimized. Fatigue caused some debonding, but the debonding was not significant enough to affect capacity. Use of ACI-318 with ACI 440 provided conservative predicted shear strengths after environmental exposure. However, the ACI approach did not provide uniform levels of safety because the observed conservatism was built into the prediction for the unstrengthened base specimens but not for the CFRP contribution. Consequently, a recommendation of the research is to apply the environmental exposure factor at the final design step to limit the effective CFRP stress/strain. For locations with very large numbers of wet freeze-thaw cycles and extended exposure to continuous moisture, the environmental reduction factors should be reduced even further. To better predict the CFRP bond strength demands that can occur due to shear-moment interaction, a further check of the design should be made beyond those required by ACI-440. Title: Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface Bonded Carbon Fiber-Reinforced Polymer Author: Higgins, Christopher, Dawson, Matthew R., Mitchell, Mikal M., Sopal, Gautam, Senturk, A. Ekin Year: 2009 This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort included determining the role of freeze-thaw, moisture, and fatigue on structural performance and developing analytical design procedures that account for durability. The results showed that moisture infiltration behind the CFRP, combined with freeze-thaw, was critical in reducing shear panel stiffness and shear capacity. Long-term moisture exposure alone produced only a minor decrease in shear capacity. Freeze-thaw, combined with fatigue, had little effect on shear capacity if water infiltration was minimized. Fatigue caused some debonding, but the debonding was not significant enough to affect capacity. Use of ACI-318 with ACI 440 provided conservative predicted shear strengths after environmental exposure. However, the ACI approach did not provide uniform levels of safety because the observed conservatism was built into the prediction for the unstrengthened base specimens but not for the CFRP contribution. Consequently, a recommendation of the research is to apply the environmental exposure factor at the final design step to limit the effective CFRP stress/strain. For locations with very large numbers of wet freeze-thaw cycles and extended exposure to continuous moisture, the environmental reduction factors should be reduced even further. To better predict the CFRP bond strength demands that can occur due to shear-moment interaction, a further check of the design should be made beyond those required by ACI-440. Close

• 31. [Article] Optimization of single- and double-flash cycles and space heating systems in geothermal engineering

  Two different problems of optimization in the utilization of geothermal energy are presented: First, the thermodynamic optimization for a geothermal power plant using a single- or double-flash process ...

  Citation × Citation Citation Abstract Copy Title: Optimization of single- and double-flash cycles and space heating systems in geothermal engineering Author: Hassoun, Talal Hussein Year: 1974 Two different problems of optimization in the utilization of geothermal energy are presented: First, the thermodynamic optimization for a geothermal power plant using a single- or double-flash process is considered; in this analysis, the optimum flash temperature giving the maximum power output is determined. Second, an economic optimization for space heating systems using geothermal energy is developed to obtain operating conditions for which the total (capital and operating) cost is a minimum. Both graphical and analytical methods are used in the thermodynamic optimization to determine the optimum flash temperature. The graphical method is based on thermodynamic data provided by an i-s (enthalpy-entropy) diagram for water and steam, in the analytical method, first and second order approximations (first and second degree polynomial approximations), are used for the functions which express enthalpy differences in terms of flash temperature. Numerical results are provided by computer programs developed for the analytical method. These results cover the temperature range normally encountered in practice. In the case of the single-flash cycle, results from both the graphical and analytical method using the first order approximation indicate the same optimum flash temperature; however, the correction factor resulting from the second order approximation improves the value of the temperature by a correction of about -2 ° C. Optimum flash temperatures for the double-flash cycle are similarly determined using the analytical method with a first order approximation. In the economic optimization of space heating systems, the analysis is made on the basis of the annual total cost per unit area of wall surface. It takes into account the cost of the geothermal fluid, cost of wall insulation, and heat exchanger cost. For a specific case where the inlet temperature to the heat exchanger is at 100° C and the outlet temperature at 28° C, the minimum annual cost to maintain a space at 20°C with an outside temperature of -l0°C is given at $0.0257 per square meter of wall area while the optimum thickness for the wall insulation is 0. 126 meter. Additional improvement in the optimization of flash temperature can be made by using a second order approximation method for the double-flash power cycle. Title: Optimization of single- and double-flash cycles and space heating systems in geothermal engineering Author: Hassoun, Talal Hussein Year: 1974 Two different problems of optimization in the utilization of geothermal energy are presented: First, the thermodynamic optimization for a geothermal power plant using a single- or double-flash process is considered; in this analysis, the optimum flash temperature giving the maximum power output is determined. Second, an economic optimization for space heating systems using geothermal energy is developed to obtain operating conditions for which the total (capital and operating) cost is a minimum. Both graphical and analytical methods are used in the thermodynamic optimization to determine the optimum flash temperature. The graphical method is based on thermodynamic data provided by an i-s (enthalpy-entropy) diagram for water and steam, in the analytical method, first and second order approximations (first and second degree polynomial approximations), are used for the functions which express enthalpy differences in terms of flash temperature. Numerical results are provided by computer programs developed for the analytical method. These results cover the temperature range normally encountered in practice. In the case of the single-flash cycle, results from both the graphical and analytical method using the first order approximation indicate the same optimum flash temperature; however, the correction factor resulting from the second order approximation improves the value of the temperature by a correction of about -2 ° C. Optimum flash temperatures for the double-flash cycle are similarly determined using the analytical method with a first order approximation. In the economic optimization of space heating systems, the analysis is made on the basis of the annual total cost per unit area of wall surface. It takes into account the cost of the geothermal fluid, cost of wall insulation, and heat exchanger cost. For a specific case where the inlet temperature to the heat exchanger is at 100° C and the outlet temperature at 28° C, the minimum annual cost to maintain a space at 20°C with an outside temperature of -l0°C is given at $0.0257 per square meter of wall area while the optimum thickness for the wall insulation is 0. 126 meter. Additional improvement in the optimization of flash temperature can be made by using a second order approximation method for the double-flash power cycle. Close

• 32. [Article] A Study on the Current State of Contaminants of Concern Research, With a Focus on Biosolids and Regulations

  Wastewater treatment plants are a major source of contaminants of emerging concern, as these facilities are the main receptors of these products via household, commercial, and industrial drains, and transport ...

  Citation × Citation Citation Abstract Copy Title: A Study on the Current State of Contaminants of Concern Research, With a Focus on Biosolids and Regulations Author: Fulton, Maren Year: 2016 Wastewater treatment plants are a major source of contaminants of emerging concern, as these facilities are the main receptors of these products via household, commercial, and industrial drains, and transport via stormwater runoff. Biosolids are composed of numerous constituents, with a number of environmentally persistent and potentially toxic contaminants of emerging concern identified as present in large concentrations. Research is needed to understand the transport and fate mechanisms of these compounds in biosolids. Additionally, this research is needed to determine a new priority framework to regulate CECs, both on the national level and regional levels. Wastewater treatment plant influent and effluent treatment regulations and practices may be improved upon as more knowledge accrues regarding contaminants of emerging concern behavior in the environment. The United States environmental regulatory process is a constant work in progress. Inherited from decades-old public health traditions, environmental regulatory programs arose to address the issues of public health as water and air quality issues surfaced. The Toxic Substances Control Act (TSCA) (15 U.S.C. 2601), enacted in 1976, provided the EPA regulatory authority to protect the environment and consumers’ health against risks posed by chemicals in commerce. TSCA only retroactively addressed chemical hazards, after they had been deemed unsafe and previously unrestricted in the public. A bill to overhaul TSCA, the Frank R. Lautenberg Chemical Safety for the 21st Century Act (House Amendment to the Senate Amendment to H.R. 2576, TSCA Modernization Act of 2015), was passed by the Senate on June 7, 2016 and sent on for President Obama’s signature. The amended law will give the EPA new authority to evaluate the safety of a new chemical before it enters the marketplace. It will also allow EPA to evaluate the safety of chemicals already known to be risks, including chemicals found to persist in the human body and in the environment. The Columbia River is presented as a case study as an example of a significant waterbody with research and regulatory gaps concerning CECs. The Columbia River waterbody was chosen as it represents an important natural resource for which data gaps exist on CEC sources and pathways into the waterbody, and which also does not receive adequate protective regulations under the national regulatory framework. Title: A Study on the Current State of Contaminants of Concern Research, With a Focus on Biosolids and Regulations Author: Fulton, Maren Year: 2016 Wastewater treatment plants are a major source of contaminants of emerging concern, as these facilities are the main receptors of these products via household, commercial, and industrial drains, and transport via stormwater runoff. Biosolids are composed of numerous constituents, with a number of environmentally persistent and potentially toxic contaminants of emerging concern identified as present in large concentrations. Research is needed to understand the transport and fate mechanisms of these compounds in biosolids. Additionally, this research is needed to determine a new priority framework to regulate CECs, both on the national level and regional levels. Wastewater treatment plant influent and effluent treatment regulations and practices may be improved upon as more knowledge accrues regarding contaminants of emerging concern behavior in the environment. The United States environmental regulatory process is a constant work in progress. Inherited from decades-old public health traditions, environmental regulatory programs arose to address the issues of public health as water and air quality issues surfaced. The Toxic Substances Control Act (TSCA) (15 U.S.C. 2601), enacted in 1976, provided the EPA regulatory authority to protect the environment and consumers’ health against risks posed by chemicals in commerce. TSCA only retroactively addressed chemical hazards, after they had been deemed unsafe and previously unrestricted in the public. A bill to overhaul TSCA, the Frank R. Lautenberg Chemical Safety for the 21st Century Act (House Amendment to the Senate Amendment to H.R. 2576, TSCA Modernization Act of 2015), was passed by the Senate on June 7, 2016 and sent on for President Obama’s signature. The amended law will give the EPA new authority to evaluate the safety of a new chemical before it enters the marketplace. It will also allow EPA to evaluate the safety of chemicals already known to be risks, including chemicals found to persist in the human body and in the environment. The Columbia River is presented as a case study as an example of a significant waterbody with research and regulatory gaps concerning CECs. The Columbia River waterbody was chosen as it represents an important natural resource for which data gaps exist on CEC sources and pathways into the waterbody, and which also does not receive adequate protective regulations under the national regulatory framework. Close

• 33. [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