Search

Search Results

• 1. [Article] Engineering a Healthier Watershed: Middle School Students Use Engineering Design to Lessen the Impact of Their Campus' Impervious Surfaces on Their Local Watershed

  It is important that students understand not only how their local watershed functions, but also how it is being impacted by impervious surfaces. Additionally, students need experience exploring the scientific ...

  Citation × Citation Citation Abstract Copy Title: Engineering a Healthier Watershed: Middle School Students Use Engineering Design to Lessen the Impact of Their Campus' Impervious Surfaces on Their Local Watershed Author: Gardner, Elizabeth Claire Year: 2015 It is important that students understand not only how their local watershed functions, but also how it is being impacted by impervious surfaces. Additionally, students need experience exploring the scientific and engineering practices that are necessary for a strong STEM background. With this knowledge students can be empowered to tackle this real and local problem using engineering design, a powerful practice gaining momentum and clarity through its prominence in the recent Framework for K-12 Science Education. Twenty classes of suburban sixth-graders participated in a new five-week Watershed Engineering Design Unit taught by their regular science teachers. Students engaged in scientific inquiry to learn about the structure, function, and health of their local watersheds, focusing on the effects of impervious surfaces. In small groups, students used the engineering design process to propose solutions to lessen the impact of runoff from their school campuses. The goal of this evaluation was to determine the effectiveness of the curriculum in terms of student gains in understanding of (1) watershed function, (2) the impact of impervious surfaces, and (3) the engineering design process. To determine the impact of this curriculum on their learning, students took multiple-choice pre- and post-assessments made up of items covering the three categories above. This data was analyzed for statistical significance using a lower-tailed paired sample t-test. All three objectives showed statistically significant learning gains and the results were used to recommend improvements to the curriculum and the assessment instrument for future iterations. Title: Engineering a Healthier Watershed: Middle School Students Use Engineering Design to Lessen the Impact of Their Campus' Impervious Surfaces on Their Local Watershed Author: Gardner, Elizabeth Claire Year: 2015 It is important that students understand not only how their local watershed functions, but also how it is being impacted by impervious surfaces. Additionally, students need experience exploring the scientific and engineering practices that are necessary for a strong STEM background. With this knowledge students can be empowered to tackle this real and local problem using engineering design, a powerful practice gaining momentum and clarity through its prominence in the recent Framework for K-12 Science Education. Twenty classes of suburban sixth-graders participated in a new five-week Watershed Engineering Design Unit taught by their regular science teachers. Students engaged in scientific inquiry to learn about the structure, function, and health of their local watersheds, focusing on the effects of impervious surfaces. In small groups, students used the engineering design process to propose solutions to lessen the impact of runoff from their school campuses. The goal of this evaluation was to determine the effectiveness of the curriculum in terms of student gains in understanding of (1) watershed function, (2) the impact of impervious surfaces, and (3) the engineering design process. To determine the impact of this curriculum on their learning, students took multiple-choice pre- and post-assessments made up of items covering the three categories above. This data was analyzed for statistical significance using a lower-tailed paired sample t-test. All three objectives showed statistically significant learning gains and the results were used to recommend improvements to the curriculum and the assessment instrument for future iterations. Close

• 2. [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

• 3. [Article] Focus on a STEM, Based in Place, Watershed Curriculum: A confluence of stormwater, humans, knowledge, attitudes, and skills

  This case study investigated the potential of a place-based watershed curriculum, using STEM principles, to increase watershed literacy and knowledge of human impacts on stormwater in the environment. ...

  Citation × Citation Citation Abstract Copy Title: Focus on a STEM, Based in Place, Watershed Curriculum: A confluence of stormwater, humans, knowledge, attitudes, and skills Author: Schall, Lecia Molineux Year: 2015 This case study investigated the potential of a place-based watershed curriculum, using STEM principles, to increase watershed literacy and knowledge of human impacts on stormwater in the environment. A secondary goal was to examine whether the place-based connection and increased exposure to issues within their local watershed impacted the students' environmental attitudes and sense of place. Over 500 sixth graders participated in this localized curriculum, where they learned the science behind watershed issues on their own school campuses. They focused on ways humans can monitor and mitigate their impacts on stormwater, through engineering investigations. The mixed-method research study investigated the effectiveness of the OLWEDU curriculum, to address these key questions: 1) To what degree did the OLWEDU increase the students' combined watershed literacy? 2) To what extent did the OLWEDU affect their environmental attitudes? 3) How did using a STEM oriented and place-based curriculum make the learning more relevant? In order to provide a solid triangulation of data, this study used a quasi-experimental design format with multiple measures: a) A Pre-Posttest (PPT), was given to all of the students to gather quantitative changes in knowledge of watershed concepts, stormwater issues related to human impacts on the environment, and engineering techniques; b) A constructed-knowledge questionnaire (CKQ) was used with forty four of the participants, to gather additional quantitative data on the students' local watershed knowledge; c) an environmental attitudes survey (EAS) was included in this sub-sample group; d) interviews were conducted with ten of the students to examine their opinions on the STEM aspects of the curriculum in addition to the place-based connections between the unit and their community. The statistically significant results showed increases in overall watershed literacy, knowledge of human impacts on stormwater, engineering principles, and environmental attitudes. These findings will be used to improve the current curriculum, and have broader implications concerning the benefits of using a formalized middle-school 21st century standards-based curriculum to teach watershed literacy and promote pro-environmental attitudes by using a combination of Science, Technology, Engineering, and Math in a local, place-based context. Title: Focus on a STEM, Based in Place, Watershed Curriculum: A confluence of stormwater, humans, knowledge, attitudes, and skills Author: Schall, Lecia Molineux Year: 2015 This case study investigated the potential of a place-based watershed curriculum, using STEM principles, to increase watershed literacy and knowledge of human impacts on stormwater in the environment. A secondary goal was to examine whether the place-based connection and increased exposure to issues within their local watershed impacted the students' environmental attitudes and sense of place. Over 500 sixth graders participated in this localized curriculum, where they learned the science behind watershed issues on their own school campuses. They focused on ways humans can monitor and mitigate their impacts on stormwater, through engineering investigations. The mixed-method research study investigated the effectiveness of the OLWEDU curriculum, to address these key questions: 1) To what degree did the OLWEDU increase the students' combined watershed literacy? 2) To what extent did the OLWEDU affect their environmental attitudes? 3) How did using a STEM oriented and place-based curriculum make the learning more relevant? In order to provide a solid triangulation of data, this study used a quasi-experimental design format with multiple measures: a) A Pre-Posttest (PPT), was given to all of the students to gather quantitative changes in knowledge of watershed concepts, stormwater issues related to human impacts on the environment, and engineering techniques; b) A constructed-knowledge questionnaire (CKQ) was used with forty four of the participants, to gather additional quantitative data on the students' local watershed knowledge; c) an environmental attitudes survey (EAS) was included in this sub-sample group; d) interviews were conducted with ten of the students to examine their opinions on the STEM aspects of the curriculum in addition to the place-based connections between the unit and their community. The statistically significant results showed increases in overall watershed literacy, knowledge of human impacts on stormwater, engineering principles, and environmental attitudes. These findings will be used to improve the current curriculum, and have broader implications concerning the benefits of using a formalized middle-school 21st century standards-based curriculum to teach watershed literacy and promote pro-environmental attitudes by using a combination of Science, Technology, Engineering, and Math in a local, place-based context. Close

• 4. [Article] Evaluating Global Sensitivity Analysis Methods for Hydrologic Modeling over the Columbia River Basin

  Global Sensitivity Analysis (GSA) approach helps to identify the effectiveness of model parameters or inputs and thus provides essential information about the model performance. The effects of 14 parameters ...

  Citation × Citation Citation Abstract Copy Title: Evaluating Global Sensitivity Analysis Methods for Hydrologic Modeling over the Columbia River Basin Author: Hameed, Maysoun Ayad Year: 2015 Global Sensitivity Analysis (GSA) approach helps to identify the effectiveness of model parameters or inputs and thus provides essential information about the model performance. The effects of 14 parameters and one input (forcing data) of the Sacramento Soil Moisture Accounting (SAC-SMA) model are analyzed by using two GSA methods: Sobol' and Fourier Amplitude Sensitivity Test (FAST). The simulations are carried out over five sub-basins within the Columbia River Basin (CRB) for three different periods: one-year, four-year, and seven-year. The main parameter sensitivities (first-order) and the interactions sensitivities (second-order) are evaluated in this study. Our results show that some hydrological processes are highly affected by the simulation length. In other words, some parameters reveal importance during the short period simulation (e.g. one-year) while other parameters are effective in the long period simulations (e.g. four-year and seven-year). Moreover, the reliability of the sensitivity analysis results is compared based on 1) the agreement between the two sensitivity analysis methods (Sobol' and FAST) in terms of highlighting the same parameters or input as the most influential parameters or input and 2) how the methods are cohered in ranking these sensitive parameters under the same conditions (sub-basins and simulation length). The results show that the coherence between the Sobol' and FAST sensitivity analysis methods. Additionally, it is found that FAST method is sufficient to evaluate the main effects of the model parameters and inputs. This study confirms that the Sobol' and FAST methods are reliable GSA methods that can be applied in different scientific applications. Finally, as a future work, we suggest to study the uncertainty associated with the sensitivity analysis approach regarding the reliability of evaluating different sensitivity analysis methods. Title: Evaluating Global Sensitivity Analysis Methods for Hydrologic Modeling over the Columbia River Basin Author: Hameed, Maysoun Ayad Year: 2015 Global Sensitivity Analysis (GSA) approach helps to identify the effectiveness of model parameters or inputs and thus provides essential information about the model performance. The effects of 14 parameters and one input (forcing data) of the Sacramento Soil Moisture Accounting (SAC-SMA) model are analyzed by using two GSA methods: Sobol' and Fourier Amplitude Sensitivity Test (FAST). The simulations are carried out over five sub-basins within the Columbia River Basin (CRB) for three different periods: one-year, four-year, and seven-year. The main parameter sensitivities (first-order) and the interactions sensitivities (second-order) are evaluated in this study. Our results show that some hydrological processes are highly affected by the simulation length. In other words, some parameters reveal importance during the short period simulation (e.g. one-year) while other parameters are effective in the long period simulations (e.g. four-year and seven-year). Moreover, the reliability of the sensitivity analysis results is compared based on 1) the agreement between the two sensitivity analysis methods (Sobol' and FAST) in terms of highlighting the same parameters or input as the most influential parameters or input and 2) how the methods are cohered in ranking these sensitive parameters under the same conditions (sub-basins and simulation length). The results show that the coherence between the Sobol' and FAST sensitivity analysis methods. Additionally, it is found that FAST method is sufficient to evaluate the main effects of the model parameters and inputs. This study confirms that the Sobol' and FAST methods are reliable GSA methods that can be applied in different scientific applications. Finally, as a future work, we suggest to study the uncertainty associated with the sensitivity analysis approach regarding the reliability of evaluating different sensitivity analysis methods. Close

• 5. [Article] Cascades Island Lamprey Passage Structure: Evaluating Passage and Migration Following Structure Modifications

  Pacific lamprey (Entosphenus tridentatus), an endemic species to the Columbia River Basin, U.S.A, has experienced staggering decreases in returns to spawning territories in recent decades. As lamprey are ...

  Citation × Citation Citation Abstract Copy Title: Cascades Island Lamprey Passage Structure: Evaluating Passage and Migration Following Structure Modifications Author: Lopez-Johnston, Siena Marie Year: 2014 Pacific lamprey (Entosphenus tridentatus), an endemic species to the Columbia River Basin, U.S.A, has experienced staggering decreases in returns to spawning territories in recent decades. As lamprey are threatened severely by a lack of passage at mainstem dams, lamprey specific passage structures have been designed and constructed to address the problem. The Cascades Island Lamprey Passage Structure (LPS) at Bonneville Dam is the longest and steepest structure of its type, following the addition of an exit pipe which allows lampreys to travel from the tailrace of the dam to the forebay. The intent of this study was to assess lamprey use of the structure and whether the structure hinders lamprey migration to subsequent dams. The study was carried out during the 2013 migration season. The study used three different treatment groups of lampreys released on five dates spanning the migration season (n=75 lamprey). Two of these groups (n=50), with different tagging methods, were released directly into the LPS to assess passage success, travel time, and tagging effect. The third group (n=25) was released into the forebay to test whether the structure impedes migration upstream. Fish were monitored via receiver arrays on the LPS and at dams on the river system. Overall passage efficiency was 74% (37 of 50 used the CI LPS successfully). Mean travel time to navigate the structure was 12 h. Fish size had no significant effect on travel time in the LPS. Water temperature had a significant effect on travel time in the LPS. There was no statistically significant effect of tagging on passage efficiency or travel time. The groups that used the LPS performed slightly better migrating upstream to the next dam than the group that bypassed the structure, but the difference was not significant. The groups that used the LPS traveled to more subsequent dams upstream than did the group that bypassed the LPS. It can be concluded that lamprey passed the structure successfully. Temperature (proxy for seasonality) had an effect on travel time in the LPS; however fish size and tagging had no effect. The LPS does not affect the ability of migrating lampreys to continue migration to subsequent dams. Such findings have important implications for management of lamprey in the region. Title: Cascades Island Lamprey Passage Structure: Evaluating Passage and Migration Following Structure Modifications Author: Lopez-Johnston, Siena Marie Year: 2014 Pacific lamprey (Entosphenus tridentatus), an endemic species to the Columbia River Basin, U.S.A, has experienced staggering decreases in returns to spawning territories in recent decades. As lamprey are threatened severely by a lack of passage at mainstem dams, lamprey specific passage structures have been designed and constructed to address the problem. The Cascades Island Lamprey Passage Structure (LPS) at Bonneville Dam is the longest and steepest structure of its type, following the addition of an exit pipe which allows lampreys to travel from the tailrace of the dam to the forebay. The intent of this study was to assess lamprey use of the structure and whether the structure hinders lamprey migration to subsequent dams. The study was carried out during the 2013 migration season. The study used three different treatment groups of lampreys released on five dates spanning the migration season (n=75 lamprey). Two of these groups (n=50), with different tagging methods, were released directly into the LPS to assess passage success, travel time, and tagging effect. The third group (n=25) was released into the forebay to test whether the structure impedes migration upstream. Fish were monitored via receiver arrays on the LPS and at dams on the river system. Overall passage efficiency was 74% (37 of 50 used the CI LPS successfully). Mean travel time to navigate the structure was 12 h. Fish size had no significant effect on travel time in the LPS. Water temperature had a significant effect on travel time in the LPS. There was no statistically significant effect of tagging on passage efficiency or travel time. The groups that used the LPS performed slightly better migrating upstream to the next dam than the group that bypassed the structure, but the difference was not significant. The groups that used the LPS traveled to more subsequent dams upstream than did the group that bypassed the LPS. It can be concluded that lamprey passed the structure successfully. Temperature (proxy for seasonality) had an effect on travel time in the LPS; however fish size and tagging had no effect. The LPS does not affect the ability of migrating lampreys to continue migration to subsequent dams. Such findings have important implications for management of lamprey in the region. Close

• 6. [Article] Quantifying the Impacts of Initial Condition and Model Uncertainty on Hydrological Forecasts

  Forecasts of hydrological information are vital for many of society's functions. Availability of water is a requirement for any civilization, and this necessitates quantitative estimates of water for effective ...

  Citation × Citation Citation Abstract Copy Title: Quantifying the Impacts of Initial Condition and Model Uncertainty on Hydrological Forecasts Author: DeChant, Caleb Matthew Year: 2014 Forecasts of hydrological information are vital for many of society's functions. Availability of water is a requirement for any civilization, and this necessitates quantitative estimates of water for effective resource management. The research in this dissertation will focus on the forecasting of hydrological quantities, with emphasis on times of anomalously low water availability, commonly referred to as droughts. Of particular focus is the quantification of uncertainty in hydrological forecasts, and the factors that affect that uncertainty. With this focus, Bayesian methods, including ensemble data assimilation and multi-model combinations, are utilized to develop a probabilistic forecasting system. This system is applied to the upper Colorado River Basin for water supply and drought forecast analysis. This dissertation examines further advancements related to the identification of drought intensity. Due to the reliance of drought forecasting on measures of the magnitude of a drought event, it is imperative that these measures be highly accurate. In order to quantify drought intensity, hydrologists typically use statistical indices, which place observed hydrological deficiencies within the context of historical climate. Although such indices are a convenient framework for understanding the intensity of a drought event, they have obstacles related to non-stationary climate, and non-uniformly distributed input variables. This dissertation discusses these shortcomings, demonstrates some errors that conventional indices may lead to, and then proposes a movement towards physically-based indices to overcome these issues. A final advancement in this dissertation is an examination of the sensitivity of hydrological forecasts to initial conditions. Although this has been performed in many recent studies, the experiment here takes a more detailed approach. Rather than determining the lead time at which meteorological forcing becomes dominant with respect to initial conditions, this study quantifies the lead time at which the forecast becomes entirely insensitive to initial conditions, and estimating the rate at which the forecast loses sensitivity to initial conditions. A primary goal with this study is to examine the recovery of drought, which is related to the loss of sensitivity to below average initial moisture conditions over time. Through this analysis, it is found that forecasts are sensitive to initial conditions at greater lead times than previously thought, which has repercussions for development of forecast systems. Title: Quantifying the Impacts of Initial Condition and Model Uncertainty on Hydrological Forecasts Author: DeChant, Caleb Matthew Year: 2014 Forecasts of hydrological information are vital for many of society's functions. Availability of water is a requirement for any civilization, and this necessitates quantitative estimates of water for effective resource management. The research in this dissertation will focus on the forecasting of hydrological quantities, with emphasis on times of anomalously low water availability, commonly referred to as droughts. Of particular focus is the quantification of uncertainty in hydrological forecasts, and the factors that affect that uncertainty. With this focus, Bayesian methods, including ensemble data assimilation and multi-model combinations, are utilized to develop a probabilistic forecasting system. This system is applied to the upper Colorado River Basin for water supply and drought forecast analysis. This dissertation examines further advancements related to the identification of drought intensity. Due to the reliance of drought forecasting on measures of the magnitude of a drought event, it is imperative that these measures be highly accurate. In order to quantify drought intensity, hydrologists typically use statistical indices, which place observed hydrological deficiencies within the context of historical climate. Although such indices are a convenient framework for understanding the intensity of a drought event, they have obstacles related to non-stationary climate, and non-uniformly distributed input variables. This dissertation discusses these shortcomings, demonstrates some errors that conventional indices may lead to, and then proposes a movement towards physically-based indices to overcome these issues. A final advancement in this dissertation is an examination of the sensitivity of hydrological forecasts to initial conditions. Although this has been performed in many recent studies, the experiment here takes a more detailed approach. Rather than determining the lead time at which meteorological forcing becomes dominant with respect to initial conditions, this study quantifies the lead time at which the forecast becomes entirely insensitive to initial conditions, and estimating the rate at which the forecast loses sensitivity to initial conditions. A primary goal with this study is to examine the recovery of drought, which is related to the loss of sensitivity to below average initial moisture conditions over time. Through this analysis, it is found that forecasts are sensitive to initial conditions at greater lead times than previously thought, which has repercussions for development of forecast systems. Close

• 7. [Article] Agricultural Management Decisions Impact Isoprene Emission and Physiology of Arundo donax, an Emerging Bioenergy Crop

  Arundo donax (Giant Reed) is quickly being developed as a rapidly-growing, robust, and highly productive bioenergy crop, with large scale cultivation of this species planned for the Columbia River basin ...

  Citation × Citation Citation Abstract Copy Title: Agricultural Management Decisions Impact Isoprene Emission and Physiology of Arundo donax, an Emerging Bioenergy Crop Author: Maxfield, Jason Charles Year: 2014 Arundo donax (Giant Reed) is quickly being developed as a rapidly-growing, robust, and highly productive bioenergy crop, with large scale cultivation of this species planned for the Columbia River basin of the Pacific Northwest (USA). Despite its potential as a next generation biomass crop, relatively few studies have examined the physiological performance of A. donax under agricultural conditions. Unlike traditional crops, A. donax is known to be a high-emitter of the volatile compound isoprene, which may significantly impact regional air quality, but it has not been widely cultivated in North America and little is known about how this species will perform in the Pacific Northwest. Over two field seasons, we measured isoprene fluxes from A. donax plants in both greenhouse conditions and in an agricultural field setting under a variety of conditions and fertilizer treatments. We also measured several other attributes of A. donax productivity and leaf physiology including chlorophyll content, photosynthesis rate, stomatal conductance, specific leaf mass, water use efficiency and gas exchange. We found that A. donax physiologically performs well under cultivation in the Columbia River basin, but that it also emits isoprene at significantly higher rates than previous reports indicate. We also found that both isoprene emission and leaf physiology were highly affected by agricultural management decisions, including nitrogen and irrigation management. Our findings indicate that crop management strategies can be developed that simultaneously seek to minimize isoprene emission while maximizing biomass production in this newly emerging bioenergy crop. Title: Agricultural Management Decisions Impact Isoprene Emission and Physiology of Arundo donax, an Emerging Bioenergy Crop Author: Maxfield, Jason Charles Year: 2014 Arundo donax (Giant Reed) is quickly being developed as a rapidly-growing, robust, and highly productive bioenergy crop, with large scale cultivation of this species planned for the Columbia River basin of the Pacific Northwest (USA). Despite its potential as a next generation biomass crop, relatively few studies have examined the physiological performance of A. donax under agricultural conditions. Unlike traditional crops, A. donax is known to be a high-emitter of the volatile compound isoprene, which may significantly impact regional air quality, but it has not been widely cultivated in North America and little is known about how this species will perform in the Pacific Northwest. Over two field seasons, we measured isoprene fluxes from A. donax plants in both greenhouse conditions and in an agricultural field setting under a variety of conditions and fertilizer treatments. We also measured several other attributes of A. donax productivity and leaf physiology including chlorophyll content, photosynthesis rate, stomatal conductance, specific leaf mass, water use efficiency and gas exchange. We found that A. donax physiologically performs well under cultivation in the Columbia River basin, but that it also emits isoprene at significantly higher rates than previous reports indicate. We also found that both isoprene emission and leaf physiology were highly affected by agricultural management decisions, including nitrogen and irrigation management. Our findings indicate that crop management strategies can be developed that simultaneously seek to minimize isoprene emission while maximizing biomass production in this newly emerging bioenergy crop. Close

• 8. [Article] Interactions Among Fuel Management, Species Composition, Bark Beetles, and Climate Change and the Potential Effects on Forests of the Lake Tahoe Basin

  Climate-driven increases in wildfires, drought conditions, and insect outbreaks are critical threats to forest carbon stores. In particular, bark beetles are important disturbance agents although their ...

  Citation × Citation Citation Abstract Copy Title: Interactions Among Fuel Management, Species Composition, Bark Beetles, and Climate Change and the Potential Effects on Forests of the Lake Tahoe Basin Author: Scheller, Robert M., Kretchun, Alec M., Loudermilk, E. Louise, Hurteau, Matthew D., Weisberg, Peter J., Skinner, Carl Year: 2017 Climate-driven increases in wildfires, drought conditions, and insect outbreaks are critical threats to forest carbon stores. In particular, bark beetles are important disturbance agents although their long-term interactions with future climate change are poorly understood. Droughts and the associated moisture deficit contribute to the onset of bark beetle outbreaks although outbreak extent and severity is dependent upon the density of host trees, wildfire, and forest management. Our objective was to estimate the effects of climate change and bark beetle outbreaks on ecosystem carbon dynamics over the next century in a western US forest. Specifically, we hypothesized that (a) bark beetle outbreaks under climate change would reduce net ecosystem carbon balance (NECB) and increase uncertainty and (b) these effects could be ameliorated by fuels management. We also examined the specific tree species dynamics—competition and release—that determined NECB response to bark beetle outbreaks. Our study area was the Lake Tahoe Basin (LTB), CA and NV, USA, an area of diverse forest types encompassing steep elevation and climatic gradients and representative of mixed-conifer forests throughout the western United States. We simulated climate change, bark beetles, wildfire, and fuels management using a landscape-scale stochastic model of disturbance and succession. We simulated the period 2010–2100 using downscaled climate projections. Recurring droughts generated conditions conducive to large-scale outbreaks; the resulting large and sustained outbreaks significantly increased the probability of LTB forests becoming C sources over decadal time scales, with slower-than-anticipated landscape-scale recovery. Tree species composition was substantially altered with a reduction in functional redundancy and productivity. Results indicate heightened uncertainty due to the synergistic influences of climate change and interacting disturbances. Our results further indicate that current fuel management practices will not be effective at reducing landscape-scale outbreak mortality. Our results provide critical insights into the interaction of drivers (bark beetles, wildfire, fuel management) that increase the risk of C loss and shifting community composition if bark beetle outbreaks become more frequent. Title: Interactions Among Fuel Management, Species Composition, Bark Beetles, and Climate Change and the Potential Effects on Forests of the Lake Tahoe Basin Author: Scheller, Robert M., Kretchun, Alec M., Loudermilk, E. Louise, Hurteau, Matthew D., Weisberg, Peter J., Skinner, Carl Year: 2017 Climate-driven increases in wildfires, drought conditions, and insect outbreaks are critical threats to forest carbon stores. In particular, bark beetles are important disturbance agents although their long-term interactions with future climate change are poorly understood. Droughts and the associated moisture deficit contribute to the onset of bark beetle outbreaks although outbreak extent and severity is dependent upon the density of host trees, wildfire, and forest management. Our objective was to estimate the effects of climate change and bark beetle outbreaks on ecosystem carbon dynamics over the next century in a western US forest. Specifically, we hypothesized that (a) bark beetle outbreaks under climate change would reduce net ecosystem carbon balance (NECB) and increase uncertainty and (b) these effects could be ameliorated by fuels management. We also examined the specific tree species dynamics—competition and release—that determined NECB response to bark beetle outbreaks. Our study area was the Lake Tahoe Basin (LTB), CA and NV, USA, an area of diverse forest types encompassing steep elevation and climatic gradients and representative of mixed-conifer forests throughout the western United States. We simulated climate change, bark beetles, wildfire, and fuels management using a landscape-scale stochastic model of disturbance and succession. We simulated the period 2010–2100 using downscaled climate projections. Recurring droughts generated conditions conducive to large-scale outbreaks; the resulting large and sustained outbreaks significantly increased the probability of LTB forests becoming C sources over decadal time scales, with slower-than-anticipated landscape-scale recovery. Tree species composition was substantially altered with a reduction in functional redundancy and productivity. Results indicate heightened uncertainty due to the synergistic influences of climate change and interacting disturbances. Our results further indicate that current fuel management practices will not be effective at reducing landscape-scale outbreak mortality. Our results provide critical insights into the interaction of drivers (bark beetles, wildfire, fuel management) that increase the risk of C loss and shifting community composition if bark beetle outbreaks become more frequent. Close

• 9. [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

• 10. [Article] Chinookan Villages of the Lower Columbia

  Villages were the center of Chinookan life, filling the role that tribes did for Native people in other parts of North America. Every village of any size or significance had a recognized leader or chief, ...

  Citation × Citation Citation Abstract Copy Title: Chinookan Villages of the Lower Columbia Author: Zenk, Henry B., Hajda, Yvonne P., Boyd, Robert Year: 2016 Villages were the center of Chinookan life, filling the role that tribes did for Native people in other parts of North America. Every village of any size or significance had a recognized leader or chief, and constituted a named local group with which its members identified themselves. Although the villages themselves are long vanished, early travelers, missionaries, and settlers have left us eyewitness accounts of what some were like. The names and approximate locations of many more can be reconstructed from historical sources and information shared by later generations of lower Columbia River Native people. As contributors to the recently published Chinookan Peoples of the Lower Columbia, one of our goals was to recreate, as best as possible given the available data, a comprehensive list of Chinookan villages on the lower Columbia River (Astoria to Cascade Locks) as they existed in the first half of the nineteenth century. The complete village list (available only online) names over eighty villages and larger groupings, representing a population of at least 15,000 people speaking Chinookan languages, and probably many more. The history and culture of these people is largely unknown to most Oregonians, yet recent and ongoing research by both academics and tribal descendants has uncovered a good deal of new information, supplementing that passed on by previous generations of scholars and their tribal consultants. The traditional culture of the Chinookan peoples constituted a successful way of living on the lower Columbia that developed over many millennia. It is the ancestral culture of the Chinook Indian Nation (embrac-ing the Clatsop and Kathlamet Chinooks of Oregon and the Lower Chinook, Wahkiakum, and Willapa Chinooks of Washington) and members of other tribal communities, as well as of fellow citizens who have Chinookan ancestry but belong to no tribal community, and it is part of our shared heritage as citizens of Oregon and Washington. The complete Chinookan Peoples of the Lower Columbia (hereafter, CPLC) village list was too long and too packed with detail to fit comfortably in the print volume, so an editorial decision was made to place it online. To make the CPLC village list more widely known and accessible to the North-west reading public, we have prepared this guide for the Oregon Historical Quarterly. Here we will summarize and describe the list in general terms and present some illustrative examples of the complexities it contains. Some of the sources we draw on have never before been utilized by scholars; and we offer new interpretations of a number of issues left unresolved by previous compilers. Title: Chinookan Villages of the Lower Columbia Author: Zenk, Henry B., Hajda, Yvonne P., Boyd, Robert Year: 2016 Villages were the center of Chinookan life, filling the role that tribes did for Native people in other parts of North America. Every village of any size or significance had a recognized leader or chief, and constituted a named local group with which its members identified themselves. Although the villages themselves are long vanished, early travelers, missionaries, and settlers have left us eyewitness accounts of what some were like. The names and approximate locations of many more can be reconstructed from historical sources and information shared by later generations of lower Columbia River Native people. As contributors to the recently published Chinookan Peoples of the Lower Columbia, one of our goals was to recreate, as best as possible given the available data, a comprehensive list of Chinookan villages on the lower Columbia River (Astoria to Cascade Locks) as they existed in the first half of the nineteenth century. The complete village list (available only online) names over eighty villages and larger groupings, representing a population of at least 15,000 people speaking Chinookan languages, and probably many more. The history and culture of these people is largely unknown to most Oregonians, yet recent and ongoing research by both academics and tribal descendants has uncovered a good deal of new information, supplementing that passed on by previous generations of scholars and their tribal consultants. The traditional culture of the Chinookan peoples constituted a successful way of living on the lower Columbia that developed over many millennia. It is the ancestral culture of the Chinook Indian Nation (embrac-ing the Clatsop and Kathlamet Chinooks of Oregon and the Lower Chinook, Wahkiakum, and Willapa Chinooks of Washington) and members of other tribal communities, as well as of fellow citizens who have Chinookan ancestry but belong to no tribal community, and it is part of our shared heritage as citizens of Oregon and Washington. The complete Chinookan Peoples of the Lower Columbia (hereafter, CPLC) village list was too long and too packed with detail to fit comfortably in the print volume, so an editorial decision was made to place it online. To make the CPLC village list more widely known and accessible to the North-west reading public, we have prepared this guide for the Oregon Historical Quarterly. Here we will summarize and describe the list in general terms and present some illustrative examples of the complexities it contains. Some of the sources we draw on have never before been utilized by scholars; and we offer new interpretations of a number of issues left unresolved by previous compilers. Close