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• 21. [Article] Infiltration and temperature characterization of a wastewater hyporheic discharge system

  The Clean Water Act imposes Total Maximum Daily Load (TMDL) limits on pollutant concentrations within wastewater effluent; in Oregon, thermal discharge is one of the pollutants subject to regulation. ...

  Citation × Citation Citation Abstract Copy Title: Infiltration and temperature characterization of a wastewater hyporheic discharge system Author: Stewart, Ryan D. The Clean Water Act imposes Total Maximum Daily Load (TMDL) limits on pollutant concentrations within wastewater effluent; in Oregon, thermal discharge is one of the pollutants subject to regulation. The City of Woodburn, Oregon, funded a series of pilot scale studies to investigate the utility of natural systems to reduce wastewater effluent temperature. The research discussed here examined the groundwater response to an unlined, 0.15 hectare wetland used to infiltrate treated wastewater into the subsurface and the potential efficacy of an upscaled discharge system. An array of geotechnical holes and monitoring wells were placed around the wetland and were equipped with pressure transducers. Groundwater level, water temperature, and water chemistry were then monitored for 1.5 years. These data were used to calibrate a series of numerical models, which were in turn utilized to assess the rate, flow direction, and spatial extent of infiltration from the wetland. Results suggest that the water table rises to the level of the wetland, and that infiltration occurs primarily through lateral flow from the wetland. Numerically-simulated and observational data found maximum water displacement velocities of 1.5 m/day in the horizontal direction, and 0.1 m/day in the vertical direction. Next, the numerical groundwater simulation model was used to predict how infiltration rate would be affected by moving from a pilot-scale to a large-scale system. It was determined that because a large percentage of flow occurs laterally through the perimeter, the specific infiltration rate will decrease as wetland area increases, due to a smaller perimeter-to-area ratio. Simulations estimated that the water displacement velocity for the large-scale (5.5 hectare) system was 0.06 m/day in the vertical direction and 0.4 m/day along the perimeter. These results were deemed consistent with a water budget performed on a separate inundated portion of the floodplain. Finally, the observed temperature and numerical simulations were used to simulate the subsurface temperature profile. It is predicted that the heat which enters the subsurface spreads out beyond a radius of 20 - 50m, and the wastewater will have its temperature transition from having daily fluctuations to seasonal fluctuations, before eventually reaching steady state. Further, it was found that mean annual temperature is a function of the distance from the wetland, thus effectively dispersing the thermal load to the river across the entire year. In an effort to translate these results to other locations, two sets of non-dimensional numbers were formulated. The first set of parameters examines the potential for cooling due to conductive losses to the atmosphere, and may indicate systems where the hydraulic retention time will be sufficient to partially or fully cool the wastewater. The second set of non-dimensional numbers provides a means by which a site's potential for hyporheic discharge may be assessed, by comparing hydraulic retention time against infiltration capacity. Altogether, the results suggest that infiltration wetland systems will reduce the peak wastewater discharge temperatures, and thus enable the City of Woodburn and other wastewater agencies to comply with their permit requirements through use of wetland recharge systems. Title: Infiltration and temperature characterization of a wastewater hyporheic discharge system Author: Stewart, Ryan D. The Clean Water Act imposes Total Maximum Daily Load (TMDL) limits on pollutant concentrations within wastewater effluent; in Oregon, thermal discharge is one of the pollutants subject to regulation. The City of Woodburn, Oregon, funded a series of pilot scale studies to investigate the utility of natural systems to reduce wastewater effluent temperature. The research discussed here examined the groundwater response to an unlined, 0.15 hectare wetland used to infiltrate treated wastewater into the subsurface and the potential efficacy of an upscaled discharge system. An array of geotechnical holes and monitoring wells were placed around the wetland and were equipped with pressure transducers. Groundwater level, water temperature, and water chemistry were then monitored for 1.5 years. These data were used to calibrate a series of numerical models, which were in turn utilized to assess the rate, flow direction, and spatial extent of infiltration from the wetland. Results suggest that the water table rises to the level of the wetland, and that infiltration occurs primarily through lateral flow from the wetland. Numerically-simulated and observational data found maximum water displacement velocities of 1.5 m/day in the horizontal direction, and 0.1 m/day in the vertical direction. Next, the numerical groundwater simulation model was used to predict how infiltration rate would be affected by moving from a pilot-scale to a large-scale system. It was determined that because a large percentage of flow occurs laterally through the perimeter, the specific infiltration rate will decrease as wetland area increases, due to a smaller perimeter-to-area ratio. Simulations estimated that the water displacement velocity for the large-scale (5.5 hectare) system was 0.06 m/day in the vertical direction and 0.4 m/day along the perimeter. These results were deemed consistent with a water budget performed on a separate inundated portion of the floodplain. Finally, the observed temperature and numerical simulations were used to simulate the subsurface temperature profile. It is predicted that the heat which enters the subsurface spreads out beyond a radius of 20 - 50m, and the wastewater will have its temperature transition from having daily fluctuations to seasonal fluctuations, before eventually reaching steady state. Further, it was found that mean annual temperature is a function of the distance from the wetland, thus effectively dispersing the thermal load to the river across the entire year. In an effort to translate these results to other locations, two sets of non-dimensional numbers were formulated. The first set of parameters examines the potential for cooling due to conductive losses to the atmosphere, and may indicate systems where the hydraulic retention time will be sufficient to partially or fully cool the wastewater. The second set of non-dimensional numbers provides a means by which a site's potential for hyporheic discharge may be assessed, by comparing hydraulic retention time against infiltration capacity. Altogether, the results suggest that infiltration wetland systems will reduce the peak wastewater discharge temperatures, and thus enable the City of Woodburn and other wastewater agencies to comply with their permit requirements through use of wetland recharge systems. Close

• 22. [Article] Lateral cavities in streams : flow structure and mean residence times from channel hydraulics, morphology, and computational fluid dynamics

  Surface transient storage (STS) and hyporheic transient storage (HTS) have functional significance in stream ecology and hydrology. Both provide refugia for aquatic communities and their longer mean residence ...

  Citation × Citation Citation Abstract Copy Title: Lateral cavities in streams : flow structure and mean residence times from channel hydraulics, morphology, and computational fluid dynamics Author: Jackson, Tracie R. (Tracie Robin) Surface transient storage (STS) and hyporheic transient storage (HTS) have functional significance in stream ecology and hydrology. Both provide refugia for aquatic communities and their longer mean residence times (compared to the main flow) increase the potential for biogeochemical reactions that can improve water quality. As STS and HTS have different storage and mass exchange mechanisms, hydrologists have proposed quantitatively separating STS from HTS to better predict solute fate and transport in streams. In addition, more accurate estimates of mass exchange parameters, such as mean residence times, are needed for STS and HTS. At present, effective solute transport parameters are estimated either from empirical relationships or by parameterizing effective transport metrics in solute transport models, resulting in empirical and nontransferrable parameters and an approximate equifinality in optimized numerical solutions. Through the development of relationships using field-measureable hydraulic and morphologic parameters, transient storage mass exchange parameters can be better constrained in solute transport models. To develop mass exchange relationships for transient storage, this dissertation focuses on the study of a prevalent and widelyrecognized type of STS termed lateral cavities. Lateral cavities have flow fields characterized by a recirculation region comprised of one or more gyres and a shear layer that spans the entire entrance. The goals of this dissertation are: (1) to develop a classification scheme that categorizes different types of STS in fluvial systems in order to quantitatively separate STS from HTS; and (2) to develop accurate estimates of mass exchange parameters (i.e., mean residence times) for lateral cavities in order to better understand and quantify solute transport and dispersion in fluvial systems. There are six major contributions of this work to the hydrology community. First, to quantitatively separate STS from HTS, a fluid-mechanics-based classification scheme is presented that identifies and categorizes different types of STS based on their characteristic mean flow structure. The classification scheme will allow for the systematic study of different STS types and development of predictive mean residence time relationships. Second, the best estimate of lateral cavity mean residence time, which represents the mean residence time of the primary gyre, is the first characteristic time of exponential decay. Third, a cavity shape factor--ratio of the square root of cavity width and depth to the cavity length--represents the degree of cavity equidimensionality and best quantifies the effect of cavity shape on mean residence time. Fourth, two roughness factors have good correlations with normalized mean residence time when computed using the median grain diameter of sediments measured in the shear layer: ratio of median grain diameter to channel depth and ratio of shear velocity to mean channel velocity. Fifth, mean residence time relationships are derived for lateral cavities in open channel flows with hydraulically smooth beds and for lateral cavities in gravel-bed rivers and streams. The mean residence time relationships are applicable for lateral cavities over a range of geometry, shape, roughness, and flow conditions. Sixth, cavity configuration (e.g., series or parallel) has a greater influence on breakthrough curve shape and transport parameters than the number of lateral cavities present. Therefore, the configuration and interaction of transient storage zones must be considered to accurately quantify stream solute transport and is a missing component in current solute transport theory. Title: Lateral cavities in streams : flow structure and mean residence times from channel hydraulics, morphology, and computational fluid dynamics Author: Jackson, Tracie R. (Tracie Robin) Surface transient storage (STS) and hyporheic transient storage (HTS) have functional significance in stream ecology and hydrology. Both provide refugia for aquatic communities and their longer mean residence times (compared to the main flow) increase the potential for biogeochemical reactions that can improve water quality. As STS and HTS have different storage and mass exchange mechanisms, hydrologists have proposed quantitatively separating STS from HTS to better predict solute fate and transport in streams. In addition, more accurate estimates of mass exchange parameters, such as mean residence times, are needed for STS and HTS. At present, effective solute transport parameters are estimated either from empirical relationships or by parameterizing effective transport metrics in solute transport models, resulting in empirical and nontransferrable parameters and an approximate equifinality in optimized numerical solutions. Through the development of relationships using field-measureable hydraulic and morphologic parameters, transient storage mass exchange parameters can be better constrained in solute transport models. To develop mass exchange relationships for transient storage, this dissertation focuses on the study of a prevalent and widelyrecognized type of STS termed lateral cavities. Lateral cavities have flow fields characterized by a recirculation region comprised of one or more gyres and a shear layer that spans the entire entrance. The goals of this dissertation are: (1) to develop a classification scheme that categorizes different types of STS in fluvial systems in order to quantitatively separate STS from HTS; and (2) to develop accurate estimates of mass exchange parameters (i.e., mean residence times) for lateral cavities in order to better understand and quantify solute transport and dispersion in fluvial systems. There are six major contributions of this work to the hydrology community. First, to quantitatively separate STS from HTS, a fluid-mechanics-based classification scheme is presented that identifies and categorizes different types of STS based on their characteristic mean flow structure. The classification scheme will allow for the systematic study of different STS types and development of predictive mean residence time relationships. Second, the best estimate of lateral cavity mean residence time, which represents the mean residence time of the primary gyre, is the first characteristic time of exponential decay. Third, a cavity shape factor--ratio of the square root of cavity width and depth to the cavity length--represents the degree of cavity equidimensionality and best quantifies the effect of cavity shape on mean residence time. Fourth, two roughness factors have good correlations with normalized mean residence time when computed using the median grain diameter of sediments measured in the shear layer: ratio of median grain diameter to channel depth and ratio of shear velocity to mean channel velocity. Fifth, mean residence time relationships are derived for lateral cavities in open channel flows with hydraulically smooth beds and for lateral cavities in gravel-bed rivers and streams. The mean residence time relationships are applicable for lateral cavities over a range of geometry, shape, roughness, and flow conditions. Sixth, cavity configuration (e.g., series or parallel) has a greater influence on breakthrough curve shape and transport parameters than the number of lateral cavities present. Therefore, the configuration and interaction of transient storage zones must be considered to accurately quantify stream solute transport and is a missing component in current solute transport theory. Close

• 23. [Article] Water quality effects of hyporheic processing

  "PB2000-107420."

  Citation × Citation Citation Abstract Copy Title: Water quality effects of hyporheic processing Author: Wigington, P.J., Landers, Dixon, Fernald, Alexander "PB2000-107420." Title: Water quality effects of hyporheic processing Author: Wigington, P.J., Landers, Dixon, Fernald, Alexander "PB2000-107420." Close

• 24. [Article] Passage, migration behavior, and autoecology of adult Pacific lamprey at Winchester Dam and within the North Umpqua River Basin, Oregon, USA

  The extensive reduction in adult Pacific lamprey (Entosphenus tridentatus) counts at many hydroelectric dams in the northwestern USA signals a substantial decline in lamprey numbers across the entire region ...

  Citation × Citation Citation Abstract Copy Title: Passage, migration behavior, and autoecology of adult Pacific lamprey at Winchester Dam and within the North Umpqua River Basin, Oregon, USA Author: Lampman, Ralph Tatsuo The extensive reduction in adult Pacific lamprey (Entosphenus tridentatus) counts at many hydroelectric dams in the northwestern USA signals a substantial decline in lamprey numbers across the entire region in the past 40 to 50 years. Among the many potential causes of this decline, obstruction of migration routes has likely played a substantial role. Within the North Umpqua River basin in southwest Oregon, USA, I focused on the following three research goals: 1) to describe the passage efficiency and migration routes of adult Pacific lamprey at Winchester Dam; 2) to evaluate the seasonal movement patterns of adult Pacific lamprey and their use of holding habitat at Winchester Dam in relation to temperature conditions; and 3) to portray the diversity of upstream migratory behaviors of adult Pacific lamprey and the environmental factors that influence these behaviors. This radio telemetry study was conducted between March 2009 and August 2011 with a combination of fixed stations and manual tracking. Passage efficiency was low in both years (8% and 19%, respectively), and all tagged lamprey that successfully passed the dam used routes other than the fish ladder. Lamprey that migrated early within the run and those with relatively small tags had higher passage rates and traveled further than the other groups of lamprey. Lamprey released above of the dam or those that passed the dam on their own distributed themselves widely in the upstream environment, suggesting that the dam deterred their upstream migration. Using mark-recapture data for the two years, the adult Pacific lamprey population upstream of Winchester Dam was estimated at 960 (95% C.I. [188, 4760]) in 2009 and 556 (95% C.I. [110, 2798]) in 2010, which was considerably lower than historical counts at the dam (between 14,532-46,785 in 1965-1971). Most tagged lamprey that did not pass the dam remained at the base of the dam at the end of the summer migration (63% in 2009 and 67% in 2010). Types of habitat most frequently used by lamprey downstream from the dam included the dam surface (wooden structures with crevices), interface zones between fast and slow water, and highway bridge pilings. The lamprey movement changed considerably between August and September, and the frequency of movements decreased sharply during this period. Tagged lamprey were detected using thermal refuges immediately downstream of the dam that were 0.4 to 2.8 C° colder than the mean river temperature at the dam, and this temperature differential increased as the season progressed. Lamprey may be seeking overwintering habitat associated with hyporheic exchange flows at the dam towards the end of the summer season after their display of heightened activity early in the summer. Ninety-five percent of the overall upstream migration took place during the first spring/summer period, and only small-scale upstream movements were observed during the winter and second spring/summer (4% and 1%, respectively). The rate of upstream migration (median) was the fastest during the initial migration phase and was 1.9 km/day (ranging from 0.3 to 11.0 km/day) for tagged lamprey released above Winchester Dam. During winter, 71% of the lamprey remained in the same location where they initiated holding. Multiple regression analysis indicated that the total upstream distance traveled by individual lamprey was most strongly related to presence/absence of Winchester Dam, relative tag size, and water temperature and photoperiod conditions at release. The presence of Winchester Dam, large relative tag size, and high water temperature / short photoperiod conditions at release significantly reduced upstream migration distance. Title: Passage, migration behavior, and autoecology of adult Pacific lamprey at Winchester Dam and within the North Umpqua River Basin, Oregon, USA Author: Lampman, Ralph Tatsuo The extensive reduction in adult Pacific lamprey (Entosphenus tridentatus) counts at many hydroelectric dams in the northwestern USA signals a substantial decline in lamprey numbers across the entire region in the past 40 to 50 years. Among the many potential causes of this decline, obstruction of migration routes has likely played a substantial role. Within the North Umpqua River basin in southwest Oregon, USA, I focused on the following three research goals: 1) to describe the passage efficiency and migration routes of adult Pacific lamprey at Winchester Dam; 2) to evaluate the seasonal movement patterns of adult Pacific lamprey and their use of holding habitat at Winchester Dam in relation to temperature conditions; and 3) to portray the diversity of upstream migratory behaviors of adult Pacific lamprey and the environmental factors that influence these behaviors. This radio telemetry study was conducted between March 2009 and August 2011 with a combination of fixed stations and manual tracking. Passage efficiency was low in both years (8% and 19%, respectively), and all tagged lamprey that successfully passed the dam used routes other than the fish ladder. Lamprey that migrated early within the run and those with relatively small tags had higher passage rates and traveled further than the other groups of lamprey. Lamprey released above of the dam or those that passed the dam on their own distributed themselves widely in the upstream environment, suggesting that the dam deterred their upstream migration. Using mark-recapture data for the two years, the adult Pacific lamprey population upstream of Winchester Dam was estimated at 960 (95% C.I. [188, 4760]) in 2009 and 556 (95% C.I. [110, 2798]) in 2010, which was considerably lower than historical counts at the dam (between 14,532-46,785 in 1965-1971). Most tagged lamprey that did not pass the dam remained at the base of the dam at the end of the summer migration (63% in 2009 and 67% in 2010). Types of habitat most frequently used by lamprey downstream from the dam included the dam surface (wooden structures with crevices), interface zones between fast and slow water, and highway bridge pilings. The lamprey movement changed considerably between August and September, and the frequency of movements decreased sharply during this period. Tagged lamprey were detected using thermal refuges immediately downstream of the dam that were 0.4 to 2.8 C° colder than the mean river temperature at the dam, and this temperature differential increased as the season progressed. Lamprey may be seeking overwintering habitat associated with hyporheic exchange flows at the dam towards the end of the summer season after their display of heightened activity early in the summer. Ninety-five percent of the overall upstream migration took place during the first spring/summer period, and only small-scale upstream movements were observed during the winter and second spring/summer (4% and 1%, respectively). The rate of upstream migration (median) was the fastest during the initial migration phase and was 1.9 km/day (ranging from 0.3 to 11.0 km/day) for tagged lamprey released above Winchester Dam. During winter, 71% of the lamprey remained in the same location where they initiated holding. Multiple regression analysis indicated that the total upstream distance traveled by individual lamprey was most strongly related to presence/absence of Winchester Dam, relative tag size, and water temperature and photoperiod conditions at release. The presence of Winchester Dam, large relative tag size, and high water temperature / short photoperiod conditions at release significantly reduced upstream migration distance. Close

• 25. [Article] Heat fluxes in the hyporheic zone of a gravel bar on the Willamette River, Oregon

  Increased water temperatures and thermal loading due to anthropogenic inputs has been shown to negatively impact the lifecycles of aquatic organisms in riverine systems (Poole and Berman 2001; Hannah, ...

  Citation × Citation Citation Abstract Copy Title: Heat fluxes in the hyporheic zone of a gravel bar on the Willamette River, Oregon Author: Squeochs, Graysen M. Increased water temperatures and thermal loading due to anthropogenic inputs has been shown to negatively impact the lifecycles of aquatic organisms in riverine systems (Poole and Berman 2001; Hannah, Malcolm et al. 2004; Quinn, Gagne et al. 2004). The studies enclosed in this thesis evaluate and quantify the heat fluxes within the hyporheic zone of a young unvegetated gravel bar on the Willamette River. The first study evaluated the application of the fiber optic distributed temperature sensing (DTS) system for thermal characterization of the shallow subsurface. The second study utilized data collected via the fiber optic DTS system, combined with data collected by thermistor probes, to calculate an energy balance for the hyporheic zone of the gravel bar. Lessons learned from the first study were that the fiber optic DTS system proved to be a flexible, high data-yielding, temperature monitoring system, but was not without limitations. The system flexibility allowed for the simultaneous temperature measurement of a 180 m² area (river and alcove combined sampling area) and multiple 2 m vertical temperature profiles with vertical resolutions of 0.022 m. Measurements made at the finest resolution of the DTS unit resulted in an increased amount of measurement variability when compared to a more traditional temperature measurement technique. An additional limitation was that the measurement sensor, the fiber optic cable, was inherently very fragile. Our recommendation for future studies is that special considerations must be taken to minimize damage to the fiber cable and signal loss. Nonetheless, the fiber optic DTS system provided an unprecedented view into the shallow subsurface. In the second study, we observed the amplitude of the thermal signal from the river decrease along a hyporheic flow path, while the net hyporheic temperature increased. Contrary to what other studies had found, no hyporheic cooling was observed. Using a simple layer control volume approach, we determined that ground-surface heating was a primary source of heat, via vadose zone storage and transport, for the hyporheic zone. The overlying conclusion of this thesis is that young, unvegetated, gravel bars on the Willamette River similar to the one examined in these studies, may increase the temperature within the hyporheic zone. Therefore, the geometry and the development of vegetation on gravel bars should be considered with regard to river engineering and planning. Title: Heat fluxes in the hyporheic zone of a gravel bar on the Willamette River, Oregon Author: Squeochs, Graysen M. Increased water temperatures and thermal loading due to anthropogenic inputs has been shown to negatively impact the lifecycles of aquatic organisms in riverine systems (Poole and Berman 2001; Hannah, Malcolm et al. 2004; Quinn, Gagne et al. 2004). The studies enclosed in this thesis evaluate and quantify the heat fluxes within the hyporheic zone of a young unvegetated gravel bar on the Willamette River. The first study evaluated the application of the fiber optic distributed temperature sensing (DTS) system for thermal characterization of the shallow subsurface. The second study utilized data collected via the fiber optic DTS system, combined with data collected by thermistor probes, to calculate an energy balance for the hyporheic zone of the gravel bar. Lessons learned from the first study were that the fiber optic DTS system proved to be a flexible, high data-yielding, temperature monitoring system, but was not without limitations. The system flexibility allowed for the simultaneous temperature measurement of a 180 m² area (river and alcove combined sampling area) and multiple 2 m vertical temperature profiles with vertical resolutions of 0.022 m. Measurements made at the finest resolution of the DTS unit resulted in an increased amount of measurement variability when compared to a more traditional temperature measurement technique. An additional limitation was that the measurement sensor, the fiber optic cable, was inherently very fragile. Our recommendation for future studies is that special considerations must be taken to minimize damage to the fiber cable and signal loss. Nonetheless, the fiber optic DTS system provided an unprecedented view into the shallow subsurface. In the second study, we observed the amplitude of the thermal signal from the river decrease along a hyporheic flow path, while the net hyporheic temperature increased. Contrary to what other studies had found, no hyporheic cooling was observed. Using a simple layer control volume approach, we determined that ground-surface heating was a primary source of heat, via vadose zone storage and transport, for the hyporheic zone. The overlying conclusion of this thesis is that young, unvegetated, gravel bars on the Willamette River similar to the one examined in these studies, may increase the temperature within the hyporheic zone. Therefore, the geometry and the development of vegetation on gravel bars should be considered with regard to river engineering and planning. Close

• 26. [Article] Groundwater Flow Model.zip

  Citation × Citation Citation Abstract Copy Title: Groundwater Flow Model.zip Author: Squeochs, Graysen M. Title: Groundwater Flow Model.zip Author: Squeochs, Graysen M. Close

• 27. [Article] Monitoring Restoration in South Sister Creek : The Effect of Stream Enhancement Structures on Water Temperature

  This pilot study of South Sister Creek (8 km length) examined stream-scale (i.e., longitudinal trends) and sub-reach scale (less than 100 m) water temperature. Hourly summer temperature time-series data ...

  Citation × Citation Citation Abstract Copy Title: Monitoring Restoration in South Sister Creek : The Effect of Stream Enhancement Structures on Water Temperature Author: Harewood, Alessandra Greer This pilot study of South Sister Creek (8 km length) examined stream-scale (i.e., longitudinal trends) and sub-reach scale (less than 100 m) water temperature. Hourly summer temperature time-series data were gathered at four to seven locations along South Sister Creek in 2006, 2012, and 2013 and were used to explore whether restoration projects (in 2007 to 2011) affected stream temperature. Calculated seven-day maximum temperatures were cooler in post-treatment years (2012 and 2013) than the pre-treatment year (2006) at all four multi-year sites with the greatest differences near the mouth of the creek (4 to 5ºC cooler). While median stream temperature values were highest in 2013 for all four of the multi-year sites, the upper quartiles of measured hourly temperature for 2006 compared to 2012 and 2013 indicated more extreme high temperatures in 2006 than in subsequent years. Cross-correlation between stream and air temperature were used as an indicator of hyporheic flow. All peak CCF coefficients indicated a strong (.70) positive correlation in the early summer period between air and stream temperature, with lags ranging from 3 to 6 hours between peak air temperature and peak stream temperature. In the late summer period, most sites demonstrated lower correlations and longer lag times, patterns consistent with greater groundwater influence during low summer flows. There was no observable difference between pre- and post-treatment air-stream temperature cross correlation relationships. At a sub-reach scale, sites with more in-stream structural complexity -- including designed structures -- displayed greater spatial temperature variability than bedrock dominated reaches with simpler geomorphology. Title: Monitoring Restoration in South Sister Creek : The Effect of Stream Enhancement Structures on Water Temperature Author: Harewood, Alessandra Greer This pilot study of South Sister Creek (8 km length) examined stream-scale (i.e., longitudinal trends) and sub-reach scale (less than 100 m) water temperature. Hourly summer temperature time-series data were gathered at four to seven locations along South Sister Creek in 2006, 2012, and 2013 and were used to explore whether restoration projects (in 2007 to 2011) affected stream temperature. Calculated seven-day maximum temperatures were cooler in post-treatment years (2012 and 2013) than the pre-treatment year (2006) at all four multi-year sites with the greatest differences near the mouth of the creek (4 to 5ºC cooler). While median stream temperature values were highest in 2013 for all four of the multi-year sites, the upper quartiles of measured hourly temperature for 2006 compared to 2012 and 2013 indicated more extreme high temperatures in 2006 than in subsequent years. Cross-correlation between stream and air temperature were used as an indicator of hyporheic flow. All peak CCF coefficients indicated a strong (.70) positive correlation in the early summer period between air and stream temperature, with lags ranging from 3 to 6 hours between peak air temperature and peak stream temperature. In the late summer period, most sites demonstrated lower correlations and longer lag times, patterns consistent with greater groundwater influence during low summer flows. There was no observable difference between pre- and post-treatment air-stream temperature cross correlation relationships. At a sub-reach scale, sites with more in-stream structural complexity -- including designed structures -- displayed greater spatial temperature variability than bedrock dominated reaches with simpler geomorphology. Close

• 28. [Article] Carbon dynamics in the hyporheic zone of a headwater mountain stream in the Cascade Mountains, Oregon

  This study investigated carbon dynamics in the hyporheic zone of a steep, forested catchment in the Cascade Mountains of western Oregon, USA. Water samples were collected monthly from a headwater stream ...

  Citation × Citation Citation Abstract Copy Title: Carbon dynamics in the hyporheic zone of a headwater mountain stream in the Cascade Mountains, Oregon Author: Corson-Rikert, Hayley A. This study investigated carbon dynamics in the hyporheic zone of a steep, forested catchment in the Cascade Mountains of western Oregon, USA. Water samples were collected monthly from a headwater stream and well network during baseflow conditions from July to December 2013 and again in March 2014. We also sampled during one fall storm event, collecting pre-storm, rising leg, and extended high flow samples. The well network is located at the base of Watershed 1 (WS1) of the H.J. Andrews Experimental Forest and spans the full width of the floodplain (~14 m) along a 29 m reach of stream. We measured pH, temperature, water level, major anions, major cations, DOC, DIC, and total alkalinity. Flow paths, travel time to wells and hydraulic conductivity were available from previous studies. During baseflow periods, hyporheic DOC decreased with median travel time through the subsurface. DIC concentrations increased with travel time, but the magnitude of this increase in DIC was too large to be explained by metabolism of stream water DOC. This suggests that there are additional sources of DIC and/or DOC in the subsurface, and that hyporheic DIC concentrations are not well linked to stream-source DOC. The most likely supplemental sources of DIC to hyporheic water are soil CO₂ and microbial respiration of DOC leached from buried particulate organic matter and from overlying soils. Overall, the hyporheic zone appears to be a source of DIC to the stream. In summer, the hyporheic zone is likely isolated from vertical infiltration or lateral inflow of soil water, and particulate organic carbon is not present in stream water. Thus, spatial patterns in hyporheic zone biogeochemistry must result from underlying spatial patterns in hyporheic flowpaths, groundwater inputs, and buried particulate organic carbon. With the transition to the rainy season throughout the fall and early winter, vertical infiltration and leaching of accumulated solutes from the overlying soil appear to become important sources of carbon that help explain patterns in hyporheic zone biogeochemistry. During a small November storm event, DOC and nitrate concentrations in the stream displayed clockwise hysteresis. Travel time appeared to be associated with both nitrate and DOC response patterns in the hyporheic zone. In wells with long travel times, DOC and nitrate concentrations showed a clockwise hysteresis pattern that mimicked and even exceeded that observed in the stream. We hypothesize that these solutes were flushed from overlying soils into the hyporheic zone via vertically infiltrating rainwater. In wells with short travel times, we observed only a small peak in DOC and nitrate concentrations during the storm, potentially due to lateral infiltration of stream water later in the event. Overall, temporal patterns in hyporheic solute chemistry during the November storm differed from patterns we observed in the well network. This suggests that whole-watershed processes that controlled stream water chemistry during this storm event were different than those that controlled solute concentrations in the hyporheic zone. Nonetheless, the hyporheic zone must have been linked to the stream. That measurements in our well network reveal a very different response between the stream and the hyporheic zone suggests that: 1) Our hyporheic zone is not representative of stream-hyporheic riparian processes that occur within the larger watershed, or 2) Hillslope-stream or within-stream processes dominate during storms, and at these times the influence of the hyporheic zone on the stream is much weaker than during baseflow. During both baseflow and storm periods, the hydrology of the WS1 system is complex – hyporheic exchange flows follow extended, non-linear flow paths through a heterogeneous subsurface and may be augmented by lateral inflows of groundwater and, during storms, vertical infiltration of soil water. Our results from both baseflow and storm sampling suggest that a complex set of physical mechanisms and biogeochemical processes influence carbon transport and transformation within this hyporheic environment. Title: Carbon dynamics in the hyporheic zone of a headwater mountain stream in the Cascade Mountains, Oregon Author: Corson-Rikert, Hayley A. This study investigated carbon dynamics in the hyporheic zone of a steep, forested catchment in the Cascade Mountains of western Oregon, USA. Water samples were collected monthly from a headwater stream and well network during baseflow conditions from July to December 2013 and again in March 2014. We also sampled during one fall storm event, collecting pre-storm, rising leg, and extended high flow samples. The well network is located at the base of Watershed 1 (WS1) of the H.J. Andrews Experimental Forest and spans the full width of the floodplain (~14 m) along a 29 m reach of stream. We measured pH, temperature, water level, major anions, major cations, DOC, DIC, and total alkalinity. Flow paths, travel time to wells and hydraulic conductivity were available from previous studies. During baseflow periods, hyporheic DOC decreased with median travel time through the subsurface. DIC concentrations increased with travel time, but the magnitude of this increase in DIC was too large to be explained by metabolism of stream water DOC. This suggests that there are additional sources of DIC and/or DOC in the subsurface, and that hyporheic DIC concentrations are not well linked to stream-source DOC. The most likely supplemental sources of DIC to hyporheic water are soil CO₂ and microbial respiration of DOC leached from buried particulate organic matter and from overlying soils. Overall, the hyporheic zone appears to be a source of DIC to the stream. In summer, the hyporheic zone is likely isolated from vertical infiltration or lateral inflow of soil water, and particulate organic carbon is not present in stream water. Thus, spatial patterns in hyporheic zone biogeochemistry must result from underlying spatial patterns in hyporheic flowpaths, groundwater inputs, and buried particulate organic carbon. With the transition to the rainy season throughout the fall and early winter, vertical infiltration and leaching of accumulated solutes from the overlying soil appear to become important sources of carbon that help explain patterns in hyporheic zone biogeochemistry. During a small November storm event, DOC and nitrate concentrations in the stream displayed clockwise hysteresis. Travel time appeared to be associated with both nitrate and DOC response patterns in the hyporheic zone. In wells with long travel times, DOC and nitrate concentrations showed a clockwise hysteresis pattern that mimicked and even exceeded that observed in the stream. We hypothesize that these solutes were flushed from overlying soils into the hyporheic zone via vertically infiltrating rainwater. In wells with short travel times, we observed only a small peak in DOC and nitrate concentrations during the storm, potentially due to lateral infiltration of stream water later in the event. Overall, temporal patterns in hyporheic solute chemistry during the November storm differed from patterns we observed in the well network. This suggests that whole-watershed processes that controlled stream water chemistry during this storm event were different than those that controlled solute concentrations in the hyporheic zone. Nonetheless, the hyporheic zone must have been linked to the stream. That measurements in our well network reveal a very different response between the stream and the hyporheic zone suggests that: 1) Our hyporheic zone is not representative of stream-hyporheic riparian processes that occur within the larger watershed, or 2) Hillslope-stream or within-stream processes dominate during storms, and at these times the influence of the hyporheic zone on the stream is much weaker than during baseflow. During both baseflow and storm periods, the hydrology of the WS1 system is complex – hyporheic exchange flows follow extended, non-linear flow paths through a heterogeneous subsurface and may be augmented by lateral inflows of groundwater and, during storms, vertical infiltration of soil water. Our results from both baseflow and storm sampling suggest that a complex set of physical mechanisms and biogeochemical processes influence carbon transport and transformation within this hyporheic environment. Close

• 29. [Article] Spatiotemporal dynamics and drivers of stream pCO₂ in a headwater mountain catchment in the Cascade Mountains, Oregon

  We examined the spatial and temporal variability of stream carbon dioxide (CO₂) and the drivers of these variations in a headwater catchment. To examine temporal variation and drivers, we measured stream ...

  Citation × Citation Citation Abstract Copy Title: Spatiotemporal dynamics and drivers of stream pCO₂ in a headwater mountain catchment in the Cascade Mountains, Oregon Author: Dosch, Nicholas T. We examined the spatial and temporal variability of stream carbon dioxide (CO₂) and the drivers of these variations in a headwater catchment. To examine temporal variation and drivers, we measured stream and hyporheic pCO₂ at high temporal resolution over 11 months in a 95.9-ha forested headwater catchment in the Western Cascades of Central Oregon, USA. Stream and hyporheic pCO₂ showed high seasonal and event-scale variability with distinct stream and hyporheic dynamics during storm discharge events. Hyporheic exchange flow exported 37.5 kg-C yr⁻¹ per watershed hectare (confidence interval 4.0-122.3 kg-C ha⁻¹ yr⁻¹) from the riparian zone to the stream. Summing CO₂ evasion and downstream advection suggests that one third of inorganic carbon export originated in the hyporheic zone. Hyporheic exchange flow had greatest influence over stream pCO₂ during low and high baseflow, while CO₂ evasion had greatest influence during storm discharge events. These findings suggest that the hyporheic zone actively participates in carbon cycling in this headwater stream and continuously replenishes stream CO₂. To examine spatial variation and drivers, we measured stream CO₂ at monthly intervals from July 2013 through July 2014 at 38 locations across the 6400-ha HJ Andrews Experimental Forest. Stream pCO₂ was consistently supersaturated with respect to atmospheric concentrations. Stream pCO₂ ranged from atmospheric (~400 μatm) to 20 times atmospheric concentrations (8150 μatm) and exhibited strong spatial and temporal variability. The distribution of pCO₂ over the study period was different in small and large streams within the drainage network. At the watershed scale, pCO₂ decreased with distance downstream. At the reach scale, we did not detect clear patterns in the downstream direction. However, individual transects displayed persistent profile shape, with consistent high and low pCO₂ locations. We found negative relationships between stream pCO₂ and stream discharge, mean velocity and the carbon dioxide gas transfer velocity. Stream pCO₂ exhibited changes over short distances, with large changes in pCO₂ over less than 50 m. Longitudinal variability indicates spatial variability of in-stream controls on pCO₂ at this scale. Stream pCO₂ shows generally higher concentrations during the summer and lower concentrations in the winter, with considerable intrannual variability. Title: Spatiotemporal dynamics and drivers of stream pCO₂ in a headwater mountain catchment in the Cascade Mountains, Oregon Author: Dosch, Nicholas T. We examined the spatial and temporal variability of stream carbon dioxide (CO₂) and the drivers of these variations in a headwater catchment. To examine temporal variation and drivers, we measured stream and hyporheic pCO₂ at high temporal resolution over 11 months in a 95.9-ha forested headwater catchment in the Western Cascades of Central Oregon, USA. Stream and hyporheic pCO₂ showed high seasonal and event-scale variability with distinct stream and hyporheic dynamics during storm discharge events. Hyporheic exchange flow exported 37.5 kg-C yr⁻¹ per watershed hectare (confidence interval 4.0-122.3 kg-C ha⁻¹ yr⁻¹) from the riparian zone to the stream. Summing CO₂ evasion and downstream advection suggests that one third of inorganic carbon export originated in the hyporheic zone. Hyporheic exchange flow had greatest influence over stream pCO₂ during low and high baseflow, while CO₂ evasion had greatest influence during storm discharge events. These findings suggest that the hyporheic zone actively participates in carbon cycling in this headwater stream and continuously replenishes stream CO₂. To examine spatial variation and drivers, we measured stream CO₂ at monthly intervals from July 2013 through July 2014 at 38 locations across the 6400-ha HJ Andrews Experimental Forest. Stream pCO₂ was consistently supersaturated with respect to atmospheric concentrations. Stream pCO₂ ranged from atmospheric (~400 μatm) to 20 times atmospheric concentrations (8150 μatm) and exhibited strong spatial and temporal variability. The distribution of pCO₂ over the study period was different in small and large streams within the drainage network. At the watershed scale, pCO₂ decreased with distance downstream. At the reach scale, we did not detect clear patterns in the downstream direction. However, individual transects displayed persistent profile shape, with consistent high and low pCO₂ locations. We found negative relationships between stream pCO₂ and stream discharge, mean velocity and the carbon dioxide gas transfer velocity. Stream pCO₂ exhibited changes over short distances, with large changes in pCO₂ over less than 50 m. Longitudinal variability indicates spatial variability of in-stream controls on pCO₂ at this scale. Stream pCO₂ shows generally higher concentrations during the summer and lower concentrations in the winter, with considerable intrannual variability. Close

• 30. [Article] Nutrient uptake in a stream affected by hydropower plants: comparison between stream channels and diversion canals

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/10750.

  Citation × Citation Citation Abstract Copy Title: Nutrient uptake in a stream affected by hydropower plants: comparison between stream channels and diversion canals Author: Izagirre, Oihana, Marti, Eugenia, Argerich, Alba, Elosegi, Arturo This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/10750. Title: Nutrient uptake in a stream affected by hydropower plants: comparison between stream channels and diversion canals Author: Izagirre, Oihana, Marti, Eugenia, Argerich, Alba, Elosegi, Arturo This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/10750. Close