Search

Search Results

• 51. [Article] Assessing Hydrologic and Water Quality Sensitivities to Precipitation Changes, Urban Growth and Land Management Using SWAT

  Precipitation changes and urban growth are two factors altering the state of water quality. Changes in precipitation will alter the amount and timing of flows, and the corresponding sediment and nutrient ...

  Citation × Citation Citation Abstract Copy Title: Assessing Hydrologic and Water Quality Sensitivities to Precipitation Changes, Urban Growth and Land Management Using SWAT Author: Psaris, Alexander Michael Year: 2014 Precipitation changes and urban growth are two factors altering the state of water quality. Changes in precipitation will alter the amount and timing of flows, and the corresponding sediment and nutrient dynamics. Meanwhile, densification associated with urban growth will create more impervious surfaces which will alter sediment and nutrient loadings. Land and water managers often rely on models to develop possible future scenarios and devise management responses to these projected changes. We use the Soil and Water Assessment Tool (SWAT) to assess the sensitivities of stream flow, sediment, and nutrient loads in two urbanizing watersheds in Northwest Oregon, USA to various climate and urbanization scenarios. We evaluate the spatial patterns climate change and urban growth will have on water, sediment and nutrient yields. We also identify critical source areas (CSAs) and investigate how implementation of vegetative filter strips (VFS) could ameliorate the effects of these changes. Our findings suggest that: 1) Water yield is tightly coupled to precipitation. 2) Large increases in winter and spring precipitation provide enough sub-surface storage to increase summertime water yields despite a moderate decrease in summer precipitation. 3) Expansion of urban areas increases surface runoff and has mixed effects on sediment and nutrients. 4) Implementation of VFS reduces pollutant loads helping overall watershed health. This research demonstrates the usefulness of SWAT in facilitating informed land and water management decisions. Title: Assessing Hydrologic and Water Quality Sensitivities to Precipitation Changes, Urban Growth and Land Management Using SWAT Author: Psaris, Alexander Michael Year: 2014 Precipitation changes and urban growth are two factors altering the state of water quality. Changes in precipitation will alter the amount and timing of flows, and the corresponding sediment and nutrient dynamics. Meanwhile, densification associated with urban growth will create more impervious surfaces which will alter sediment and nutrient loadings. Land and water managers often rely on models to develop possible future scenarios and devise management responses to these projected changes. We use the Soil and Water Assessment Tool (SWAT) to assess the sensitivities of stream flow, sediment, and nutrient loads in two urbanizing watersheds in Northwest Oregon, USA to various climate and urbanization scenarios. We evaluate the spatial patterns climate change and urban growth will have on water, sediment and nutrient yields. We also identify critical source areas (CSAs) and investigate how implementation of vegetative filter strips (VFS) could ameliorate the effects of these changes. Our findings suggest that: 1) Water yield is tightly coupled to precipitation. 2) Large increases in winter and spring precipitation provide enough sub-surface storage to increase summertime water yields despite a moderate decrease in summer precipitation. 3) Expansion of urban areas increases surface runoff and has mixed effects on sediment and nutrients. 4) Implementation of VFS reduces pollutant loads helping overall watershed health. This research demonstrates the usefulness of SWAT in facilitating informed land and water management decisions. Close

• 52. [Article] Working for the "Working River": Willamette River Water Pollution, 1926 to 1962

  Efforts to abate Willamette River pollution between 1926 and 1962 centered on a struggle between abatement advocates and the two primary polluters in the watershed, the City of Portland and the pulp and ...

  Citation × Citation Citation Abstract Copy Title: Working for the "Working River": Willamette River Water Pollution, 1926 to 1962 Author: Hillegas, James Vincent Year: 2009 Efforts to abate Willamette River pollution between 1926 and 1962 centered on a struggle between abatement advocates and the two primary polluters in the watershed, the City of Portland and the pulp and paper industry. Throughout the twentieth century, the Willamette was by far the most heavily populated and industrialized watershed in Oregon. Like many other of the world's rivers, the Willamette was an integral part of municipal and industrial waste removal systems. As such, the main stem of the river carried the combined wastes from sewage outfalls serving hundreds of thousands of people and millions of gallons daily of pulp and paper making effluents. Exacerbating the impacts of these pollutants on the Willamette were unavoidable geologic and hydrologic constraints impacting the river's flow and, therefore, the river's ability to dilute wastes. As the pollution load in the Willamette River increased throughout the twentieth century, accustomed activities such as recreation, sports fishing, and commercial fishing, were constrained. The polluted water also threatened potential uses of the river, such as tourism and expanded recreation after World War II. To address these concerns, beginning in 1926 clean streams advocates created ad hoc groups of public health experts, sanitary engineers, conservationists, sportsmen, and others to pressure Portland officials and industry representatives to cease polluting the river. In November 1938, continued activism and lobbying from these groups led to the passage of a citizen's initiative creating the Oregon State Sanitary Authority (OSSA). From 1939 to 1962, the OSSA took the lead in the water pollution abatement issue and realized some limited successes including pushing Portland and other cities to build sewage treatment plants and regulating pulp and paper mill discharges. However, in spite of these accomplishments, the issue of water quality grew more complex and difficult through the 1950s, as reflected in Tom McCall's November 1962 television documentary Pollution in Paradise. Title: Working for the "Working River": Willamette River Water Pollution, 1926 to 1962 Author: Hillegas, James Vincent Year: 2009 Efforts to abate Willamette River pollution between 1926 and 1962 centered on a struggle between abatement advocates and the two primary polluters in the watershed, the City of Portland and the pulp and paper industry. Throughout the twentieth century, the Willamette was by far the most heavily populated and industrialized watershed in Oregon. Like many other of the world's rivers, the Willamette was an integral part of municipal and industrial waste removal systems. As such, the main stem of the river carried the combined wastes from sewage outfalls serving hundreds of thousands of people and millions of gallons daily of pulp and paper making effluents. Exacerbating the impacts of these pollutants on the Willamette were unavoidable geologic and hydrologic constraints impacting the river's flow and, therefore, the river's ability to dilute wastes. As the pollution load in the Willamette River increased throughout the twentieth century, accustomed activities such as recreation, sports fishing, and commercial fishing, were constrained. The polluted water also threatened potential uses of the river, such as tourism and expanded recreation after World War II. To address these concerns, beginning in 1926 clean streams advocates created ad hoc groups of public health experts, sanitary engineers, conservationists, sportsmen, and others to pressure Portland officials and industry representatives to cease polluting the river. In November 1938, continued activism and lobbying from these groups led to the passage of a citizen's initiative creating the Oregon State Sanitary Authority (OSSA). From 1939 to 1962, the OSSA took the lead in the water pollution abatement issue and realized some limited successes including pushing Portland and other cities to build sewage treatment plants and regulating pulp and paper mill discharges. However, in spite of these accomplishments, the issue of water quality grew more complex and difficult through the 1950s, as reflected in Tom McCall's November 1962 television documentary Pollution in Paradise. Close

• 53. [Article] Estimation of Historic Flows and Sediment Loads to San Francisco Bay, 1849 – 2011

  River flow and sediment transport in estuaries influence morphological development over decadal and century time scales, but hydrological and sedimentological records are typically too short to adequately ...

  Citation × Citation Citation Abstract Copy Title: Estimation of Historic Flows and Sediment Loads to San Francisco Bay, 1849 – 2011 Author: Moftakhari Rostamkhani, Hamed, Jay, David A., Talke, Stefan A., Schoellhamer, David H. Year: 2015 River flow and sediment transport in estuaries influence morphological development over decadal and century time scales, but hydrological and sedimentological records are typically too short to adequately characterize long-term trends. In this study, we recover archival records and apply a rating curve approach to develop the first instrumental estimates of daily delta inflow and sediment loads to San Francisco Bay (1849 – 1929). The total sediment load is constrained using sedimentation/erosion estimated from bathymetric survey data to produce continuous daily sediment transport estimates from 1849 to 1955, the time period prior to sediment load measurements. We estimate that ~55% (45 – 75%) of the ~1500±400 million tons (Mt) of sediment delivered to the estuary between 1849 and 2011 was the result of anthropogenic alteration in the watershed that increased sediment supply. Also, the seasonal timing of sediment flux events has shifted because significant spring-melt floods have decreased, causing estimated springtime transport (April 1st to June 30th) to decrease from ~25% to ~15% of the annual total. By contrast, wintertime sediment loads (December 1st to March 31st) have increased from ~70% to ~80%. A ~35% reduction of annual flow since the 19th century along with decreased sediment supply has resulted in a ~50% reduction in annual sediment delivery. The methods developed in this study can be applied to other systems for which unanalyzed historic data exist. Title: Estimation of Historic Flows and Sediment Loads to San Francisco Bay, 1849 – 2011 Author: Moftakhari Rostamkhani, Hamed, Jay, David A., Talke, Stefan A., Schoellhamer, David H. Year: 2015 River flow and sediment transport in estuaries influence morphological development over decadal and century time scales, but hydrological and sedimentological records are typically too short to adequately characterize long-term trends. In this study, we recover archival records and apply a rating curve approach to develop the first instrumental estimates of daily delta inflow and sediment loads to San Francisco Bay (1849 – 1929). The total sediment load is constrained using sedimentation/erosion estimated from bathymetric survey data to produce continuous daily sediment transport estimates from 1849 to 1955, the time period prior to sediment load measurements. We estimate that ~55% (45 – 75%) of the ~1500±400 million tons (Mt) of sediment delivered to the estuary between 1849 and 2011 was the result of anthropogenic alteration in the watershed that increased sediment supply. Also, the seasonal timing of sediment flux events has shifted because significant spring-melt floods have decreased, causing estimated springtime transport (April 1st to June 30th) to decrease from ~25% to ~15% of the annual total. By contrast, wintertime sediment loads (December 1st to March 31st) have increased from ~70% to ~80%. A ~35% reduction of annual flow since the 19th century along with decreased sediment supply has resulted in a ~50% reduction in annual sediment delivery. The methods developed in this study can be applied to other systems for which unanalyzed historic data exist. Close

• 54. [Article] Landforms along the Lower Columbia River and the Influence of Humans

  River systems, such as the Columbia River in the Pacific Northwest, USA have been influenced by human activities, resulting in changes to the physical processes that drive landform evolution. This work ...

  Citation × Citation Citation Abstract Copy Title: Landforms along the Lower Columbia River and the Influence of Humans Author: Cannon, Charles Matthew Year: 2015 River systems, such as the Columbia River in the Pacific Northwest, USA have been influenced by human activities, resulting in changes to the physical processes that drive landform evolution. This work describes an inventory of landforms along the Columbia River estuary between the Pacific Ocean and Bonneville Dam in Oregon and Washington. Groupings of landforms are assigned to formative process regimes that are used to assess historical changes to floodplain features. The estuary was historically a complex system of channels with a floodplain dominated by extensive tidal wetlands in the lower reaches and backswamp lakes and wetlands in upper reaches. Natural levees flank most channels in the upper reaches, locally including areas of ridge and swale topography and crevasse splays that intrude into backswamps. Other Holocene process regimes affecting floodplain morphology have included volcanogenic deltas, tributary fans, dunes, and landslides. Pre-Holocene landforms are locally prominent and include ancient fluvial deposits and bedrock. Historical changes to streamflow regimes, floodplain isolation by flood-control systems, and direct anthropogenic disturbance have resulted in channel narrowing and limited the amount of floodplain that can be shaped by flowing water. Floodplain isolation has caused relative subsidence of tidal floodplains along much of the lower estuary. Most extant landforms are on trajectories controlled by humans and new landforms are mostly created by humans. Title: Landforms along the Lower Columbia River and the Influence of Humans Author: Cannon, Charles Matthew Year: 2015 River systems, such as the Columbia River in the Pacific Northwest, USA have been influenced by human activities, resulting in changes to the physical processes that drive landform evolution. This work describes an inventory of landforms along the Columbia River estuary between the Pacific Ocean and Bonneville Dam in Oregon and Washington. Groupings of landforms are assigned to formative process regimes that are used to assess historical changes to floodplain features. The estuary was historically a complex system of channels with a floodplain dominated by extensive tidal wetlands in the lower reaches and backswamp lakes and wetlands in upper reaches. Natural levees flank most channels in the upper reaches, locally including areas of ridge and swale topography and crevasse splays that intrude into backswamps. Other Holocene process regimes affecting floodplain morphology have included volcanogenic deltas, tributary fans, dunes, and landslides. Pre-Holocene landforms are locally prominent and include ancient fluvial deposits and bedrock. Historical changes to streamflow regimes, floodplain isolation by flood-control systems, and direct anthropogenic disturbance have resulted in channel narrowing and limited the amount of floodplain that can be shaped by flowing water. Floodplain isolation has caused relative subsidence of tidal floodplains along much of the lower estuary. Most extant landforms are on trajectories controlled by humans and new landforms are mostly created by humans. Close

• 55. [Article] Climate Change Assessment in Columbia River Basin (CRB) Using Copula Based on Coupling of Temperature and Precipitation

  The multi downscaled-scenario products allow us to better assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Joint Probability distribution functions ...

  Citation × Citation Citation Abstract Copy Title: Climate Change Assessment in Columbia River Basin (CRB) Using Copula Based on Coupling of Temperature and Precipitation Author: Qin, Yueyue Year: 2015 The multi downscaled-scenario products allow us to better assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Joint Probability distribution functions (PDFs), of both the climatic variables, might help better understand the interdependence of the two, and thus in-turn help in accessing the future with confidence. In the present study, we have used multi-modelled statistically downscaled ensemble of precipitation and temperature variables. The dataset used is multi-model ensemble of 10 Global Climate Models (GCMs) downscaled product from CMIP5 daily dataset, using the Bias Correction and Spatial Downscaling (BCSD) technique, generated at Portland State University. The multi-model ensemble PDFs of both precipitation and temperature is evaluated for summer (dry) and winter (wet) periods for 10 sub-basins across Columbia River Basin (CRB). Eventually, Copula is applied to establish the joint distribution of two variables on multi-model ensemble data. Results have indicated that the probabilistic distribution helps remove the limitations on marginal distributions of variables in question and helps in better prediction. The joint distribution is then used to estimate the change in trends of said variables in future, along with estimation of the probabilities of the given change. The joint distribution trends are varied, but certainly positive, for summer and winter time scales based on sub-basins. Dry season, generally, is indicating towards higher positive changes in precipitation than temperature (as compared to historical) across sub-basins with wet season inferring otherwise. Probabilities of changes in future, as estimated by the joint precipitation and temperature, also indicates varied degree and forms during dry season whereas the wet season is rather constant across all the sub-basins. Title: Climate Change Assessment in Columbia River Basin (CRB) Using Copula Based on Coupling of Temperature and Precipitation Author: Qin, Yueyue Year: 2015 The multi downscaled-scenario products allow us to better assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Joint Probability distribution functions (PDFs), of both the climatic variables, might help better understand the interdependence of the two, and thus in-turn help in accessing the future with confidence. In the present study, we have used multi-modelled statistically downscaled ensemble of precipitation and temperature variables. The dataset used is multi-model ensemble of 10 Global Climate Models (GCMs) downscaled product from CMIP5 daily dataset, using the Bias Correction and Spatial Downscaling (BCSD) technique, generated at Portland State University. The multi-model ensemble PDFs of both precipitation and temperature is evaluated for summer (dry) and winter (wet) periods for 10 sub-basins across Columbia River Basin (CRB). Eventually, Copula is applied to establish the joint distribution of two variables on multi-model ensemble data. Results have indicated that the probabilistic distribution helps remove the limitations on marginal distributions of variables in question and helps in better prediction. The joint distribution is then used to estimate the change in trends of said variables in future, along with estimation of the probabilities of the given change. The joint distribution trends are varied, but certainly positive, for summer and winter time scales based on sub-basins. Dry season, generally, is indicating towards higher positive changes in precipitation than temperature (as compared to historical) across sub-basins with wet season inferring otherwise. Probabilities of changes in future, as estimated by the joint precipitation and temperature, also indicates varied degree and forms during dry season whereas the wet season is rather constant across all the sub-basins. Close

• 56. [Article] Soil Moisture Gradients and Controls on a Southern Appalachian Hillslope from Drought Through Recharge

  Soil moisture gradients along hillslopes in humid watersheds, although indicated by vegetation gradients and by studies using models, have been difficult to confirm empirically. While soil properties and ...

  Citation × Citation Citation Abstract Copy Title: Soil Moisture Gradients and Controls on a Southern Appalachian Hillslope from Drought Through Recharge Author: Yeakley, J. Alan, Swank, W. T., Swift, L. W., Hornberger, G. M., Shugart, H. H. Year: 1998 Soil moisture gradients along hillslopes in humid watersheds, although indicated by vegetation gradients and by studies using models, have been difficult to confirm empirically. While soil properties and topographic features are the two general physio-graphic factors controlling soil moisture on hillslopes, studies have shown conflicting results regarding which factor is more important. The relative importance of topographic and soil property controls was examined in an upland forested watershed at the Coweeta Hydrologic Laboratory in the southern Appalachian mountains. Soil moisture was measured along a hillslope transect with a mesic-to-xeric forest vegetation gradient over a period spanning precipitation extremes. The hillslope was transect instrumented with a time domain reflectometry (TDR) network at two depths. Soil moisture was measured during a severe autumn drought and subsequent winter precipitation recharge. In the upper soil depth (0-30 cm), moisture gradients persisted throughout the measurement period, and topography exerted dominant control. For the entire root zone (0-90 cm), soil moisture gradients were found only during drought. Control on soil moisture was due to both topography and storage before drought. During and after recharge, variations in soil texture and horizon distribution exerted dominant control on soil moisture content in the root zone (0-90 cm). These results indicate that topographic factors assert more control over hillslope soil moisture during drier periods as drainage progresses, while variations in soil water storage properties are more important during wetter periods. Hillslope soil moisture gradients in southern Appalachian watersheds appear to be restricted to upper soil layers, with deeper hillslope soil moisture gradients occurring only with sufficient drought. Title: Soil Moisture Gradients and Controls on a Southern Appalachian Hillslope from Drought Through Recharge Author: Yeakley, J. Alan, Swank, W. T., Swift, L. W., Hornberger, G. M., Shugart, H. H. Year: 1998 Soil moisture gradients along hillslopes in humid watersheds, although indicated by vegetation gradients and by studies using models, have been difficult to confirm empirically. While soil properties and topographic features are the two general physio-graphic factors controlling soil moisture on hillslopes, studies have shown conflicting results regarding which factor is more important. The relative importance of topographic and soil property controls was examined in an upland forested watershed at the Coweeta Hydrologic Laboratory in the southern Appalachian mountains. Soil moisture was measured along a hillslope transect with a mesic-to-xeric forest vegetation gradient over a period spanning precipitation extremes. The hillslope was transect instrumented with a time domain reflectometry (TDR) network at two depths. Soil moisture was measured during a severe autumn drought and subsequent winter precipitation recharge. In the upper soil depth (0-30 cm), moisture gradients persisted throughout the measurement period, and topography exerted dominant control. For the entire root zone (0-90 cm), soil moisture gradients were found only during drought. Control on soil moisture was due to both topography and storage before drought. During and after recharge, variations in soil texture and horizon distribution exerted dominant control on soil moisture content in the root zone (0-90 cm). These results indicate that topographic factors assert more control over hillslope soil moisture during drier periods as drainage progresses, while variations in soil water storage properties are more important during wetter periods. Hillslope soil moisture gradients in southern Appalachian watersheds appear to be restricted to upper soil layers, with deeper hillslope soil moisture gradients occurring only with sufficient drought. Close

• 57. [Article] Estimating Watershed Biodiversity: An Empirical Study of the Chesapeake Bay in Maryland, USA

  There has been increasing demand for rigorous methods for evaluating biodiversity, one of the ecosystem services that sustains and fulfills human life. After carefully examining the literature, we found ...

  Citation × Citation Citation Abstract Copy Title: Estimating Watershed Biodiversity: An Empirical Study of the Chesapeake Bay in Maryland, USA Author: Morimoto, Junko, Voinov, Helena, Wilson, Matthew A., Costanza, Robert Year: 2003 There has been increasing demand for rigorous methods for evaluating biodiversity, one of the ecosystem services that sustains and fulfills human life. After carefully examining the literature, we found three key points that should be taken into account when we evaluate biodiversity. The first point is that any "indicator species" tends to be a leaky target of biodiversity. The second point is that "buffering" that is useful for representing the ecological concept of boundaries should have scientific meanings. The third point is that a "watershed" that integrates most natural processes is advantageous as the spatial range for evaluation. Based on these considerations, we developed the Biodiversity Probability Index (BPI) to account for biodiversity. We analyzed the relationship between BPI and total economic value of ecosystem services per unit area in order to test the reliability and utility of BPI. All BPI values were under a positive regression curve. The curve showed the highest economic value that could be achieved at a given biodiversity status. Based on our findings along the analysis, we conclude that the BPI has two advantages: (1) The BPI identifies the extent of the impact on biodiversity within a given landscape, and its composition of each category of species helps to identify what kind of wild life habitat could be seriously threatened by future land use development; (2) The BPI tells not only the biodiversity condition in ecological sense, but also provides the potential total economic value of ecosystem services, which will be achieved under ideal conditions. Title: Estimating Watershed Biodiversity: An Empirical Study of the Chesapeake Bay in Maryland, USA Author: Morimoto, Junko, Voinov, Helena, Wilson, Matthew A., Costanza, Robert Year: 2003 There has been increasing demand for rigorous methods for evaluating biodiversity, one of the ecosystem services that sustains and fulfills human life. After carefully examining the literature, we found three key points that should be taken into account when we evaluate biodiversity. The first point is that any "indicator species" tends to be a leaky target of biodiversity. The second point is that "buffering" that is useful for representing the ecological concept of boundaries should have scientific meanings. The third point is that a "watershed" that integrates most natural processes is advantageous as the spatial range for evaluation. Based on these considerations, we developed the Biodiversity Probability Index (BPI) to account for biodiversity. We analyzed the relationship between BPI and total economic value of ecosystem services per unit area in order to test the reliability and utility of BPI. All BPI values were under a positive regression curve. The curve showed the highest economic value that could be achieved at a given biodiversity status. Based on our findings along the analysis, we conclude that the BPI has two advantages: (1) The BPI identifies the extent of the impact on biodiversity within a given landscape, and its composition of each category of species helps to identify what kind of wild life habitat could be seriously threatened by future land use development; (2) The BPI tells not only the biodiversity condition in ecological sense, but also provides the potential total economic value of ecosystem services, which will be achieved under ideal conditions. Close

• 58. [Article] Effects of Tide Gate Replacement on Water Temperature ina Freshwater Slough in the Columbia River Estuary

  Dramatic declines in salmon populations in the Pacific Northwest have brought new attention to the importance of estuarine rearing habitats. Levees and tide gates used to convert estuarine wetlands into ...

  Citation × Citation Citation Abstract Copy Title: Effects of Tide Gate Replacement on Water Temperature ina Freshwater Slough in the Columbia River Estuary Author: Ennis, Sara Year: 2009 Dramatic declines in salmon populations in the Pacific Northwest have brought new attention to the importance of estuarine rearing habitats. Levees and tide gates used to convert estuarine wetlands into farmland have reduced available habitat by more than half of historical levels. Recent efforts to restore estuarine habitats include tide gate replacement, though this method has been poorly studied. As a key indicator of salmon habitat suitability, temperature was used to evaluate the effects of tide gate replacement in a tidally influenced freshwater slough in the Lower Columbia River estuary. Three tide gates in the largest slough on Tenasillahe Island were replaced in 2007 with side-hinged aluminum gates. As managed during the data collection periods, the new tide gates did not allow tidal inflow into the slough. The study employed a Before-After, Control-Impact (BACI) approach, collecting data seasonally two years before and after replacement at the impact site and at the control site, a relatively unaltered slough on nearby Welch Island. Randomized Intervention Analysis and Monte Carlo tests revealed no significant difference in slough water temperatures after tide gate replacement, although minimum temperatures dropped up and downstream of the tide gates. Although the new tide gates did not have a significant effect on water temperature, the lower minimum temperatures may have been caused by a slight increase in tidal circulation. This result suggests that slough temperatures would decrease if the tide gates were managed to increase tidal inflow, and thus improve the quality of salmon rearing habitat. Title: Effects of Tide Gate Replacement on Water Temperature ina Freshwater Slough in the Columbia River Estuary Author: Ennis, Sara Year: 2009 Dramatic declines in salmon populations in the Pacific Northwest have brought new attention to the importance of estuarine rearing habitats. Levees and tide gates used to convert estuarine wetlands into farmland have reduced available habitat by more than half of historical levels. Recent efforts to restore estuarine habitats include tide gate replacement, though this method has been poorly studied. As a key indicator of salmon habitat suitability, temperature was used to evaluate the effects of tide gate replacement in a tidally influenced freshwater slough in the Lower Columbia River estuary. Three tide gates in the largest slough on Tenasillahe Island were replaced in 2007 with side-hinged aluminum gates. As managed during the data collection periods, the new tide gates did not allow tidal inflow into the slough. The study employed a Before-After, Control-Impact (BACI) approach, collecting data seasonally two years before and after replacement at the impact site and at the control site, a relatively unaltered slough on nearby Welch Island. Randomized Intervention Analysis and Monte Carlo tests revealed no significant difference in slough water temperatures after tide gate replacement, although minimum temperatures dropped up and downstream of the tide gates. Although the new tide gates did not have a significant effect on water temperature, the lower minimum temperatures may have been caused by a slight increase in tidal circulation. This result suggests that slough temperatures would decrease if the tide gates were managed to increase tidal inflow, and thus improve the quality of salmon rearing habitat. Close

• 59. [Article] Drainage Reversals Due to Tectonic Uplift: an Investigation through Modeling

  In mountainous landscapes throughout the world bedrock dominated river channels record a history of the tectonic and climatic evolution of the drainage basins that contain them. In traditional analysis ...

  Citation × Citation Citation Abstract Copy Title: Drainage Reversals Due to Tectonic Uplift: an Investigation through Modeling Author: Bordal, Max Gregory Year: 2014 In mountainous landscapes throughout the world bedrock dominated river channels record a history of the tectonic and climatic evolution of the drainage basins that contain them. In traditional analysis of river profiles, uplift and erosion are considered to be in balance in a steady state. In this study the transient state of a drainage basin is explored and numerically modeled, where a Gaussian shaped pulse of tectonic uplift overwhelms the river's incision and forces a diversion of the drainage network. I review the derivation of and use the detachment limited stream power equation to execute a model to find the physical condition that produce these dramatic drainage response. The Eel River and the unique tectonics of the nearby Mendocino Triple Junction, a well-researched case study in this phenomenon, provide context and parameters. The results of my models suggest that a rapid increase in uplift and a low erosion factor are the two most important conditions for a diversion response. Title: Drainage Reversals Due to Tectonic Uplift: an Investigation through Modeling Author: Bordal, Max Gregory Year: 2014 In mountainous landscapes throughout the world bedrock dominated river channels record a history of the tectonic and climatic evolution of the drainage basins that contain them. In traditional analysis of river profiles, uplift and erosion are considered to be in balance in a steady state. In this study the transient state of a drainage basin is explored and numerically modeled, where a Gaussian shaped pulse of tectonic uplift overwhelms the river's incision and forces a diversion of the drainage network. I review the derivation of and use the detachment limited stream power equation to execute a model to find the physical condition that produce these dramatic drainage response. The Eel River and the unique tectonics of the nearby Mendocino Triple Junction, a well-researched case study in this phenomenon, provide context and parameters. The results of my models suggest that a rapid increase in uplift and a low erosion factor are the two most important conditions for a diversion response. Close

• 60. [Article] The stratigraphy and structure of the Columbia River basalt group in the Bull Run watershed, Multnomah and Clackamas Counties, Oregon

  Approximately 150 meters (500 feet) of Grande Ronde Basalt and 140 meters (450 feet) of Wanapum Basalt of the Columbia River Basalt Group are exposed in the Bull Run Watershed. In Bull Run, the Grande ...

  Citation × Citation Citation Abstract Copy Title: The stratigraphy and structure of the Columbia River basalt group in the Bull Run watershed, Multnomah and Clackamas Counties, Oregon Author: Vogt, Beverly Frobenius Year: 1981 Approximately 150 meters (500 feet) of Grande Ronde Basalt and 140 meters (450 feet) of Wanapum Basalt of the Columbia River Basalt Group are exposed in the Bull Run Watershed. In Bull Run, the Grande Ronde Basalt is divided into three mappable units: "low Mg" R2 (at least one flow), "low Mg" N2 (approximately four flows), and "high Mg" N2 (two to three flows}. The Wanapum Basalt is represented by two members: Frenchman Springs Member (six flows) and Priest Rapids Member (one flow). These units are identified by instrumental neutron activation analysis, paleomagnetism based on measurements with a fluxgate magnetometer, petrography, lithology, jointing, and stratigraphic position. Title: The stratigraphy and structure of the Columbia River basalt group in the Bull Run watershed, Multnomah and Clackamas Counties, Oregon Author: Vogt, Beverly Frobenius Year: 1981 Approximately 150 meters (500 feet) of Grande Ronde Basalt and 140 meters (450 feet) of Wanapum Basalt of the Columbia River Basalt Group are exposed in the Bull Run Watershed. In Bull Run, the Grande Ronde Basalt is divided into three mappable units: "low Mg" R2 (at least one flow), "low Mg" N2 (approximately four flows), and "high Mg" N2 (two to three flows}. The Wanapum Basalt is represented by two members: Frenchman Springs Member (six flows) and Priest Rapids Member (one flow). These units are identified by instrumental neutron activation analysis, paleomagnetism based on measurements with a fluxgate magnetometer, petrography, lithology, jointing, and stratigraphic position. Close