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• 11. [Article] Economic analysis of restoration practices to improve water quality and fish habitat of a large river floodplain : a case study of the Willamette River, Oregon

  In- stream water temperature is one of the most important environmental factors associated with the decline in salmonid populations and their habitats in the Pacific Northwest. Most ecological restoration ...

  Citation × Citation Citation Abstract Copy Title: Economic analysis of restoration practices to improve water quality and fish habitat of a large river floodplain : a case study of the Willamette River, Oregon Author: Seedang, Saichon In- stream water temperature is one of the most important environmental factors associated with the decline in salmonid populations and their habitats in the Pacific Northwest. Most ecological restoration practices that attempt to reduce instream temperatures center on replanting or reestablishing riparian vegetation and increasing flows. However, in a large floodplain river like the Willamette, restoring hyporheic flow may also play an important role in reducing water temperature. The objective of this dissertation is to examine restoration practices that focus on the reduction of water temperatures in the upper mainstem Willamette River, Oregon, for the benefit of salmonid species. Economic information is developed to determine the cost-effectiveness of water temperature reduction strategies. The CEQUAL- W2 water temperature model is used to simulate the effects of upstream combinations of riparian shading and flow increments on downstream water temperatures. Costs associated with these strategies are estimated. These costs consist of the opportunity costs of losing agricultural production, and losing recreation due to flow releases from up-stream reservoirs. The effectiveness of each strategy in reducing water temperature and the associated costs are used to construct a cost-effectiveness frontier. The results indicate that the cumulative effects of shading and flows have little impact on temperature reduction downstream. Even when maximum available resources are allocated to investments in shade and flow increases they cannot lower summer water temperatures sufficiently to meet the state water temperature standard. However, the restoration practices selected from the cost-effectiveness frontiers method do provide ranges of achievable temperature reductions at minimum costs. These results are thus useful management tools when selecting policies to pursue water temperature goals. Hyporheic temperature reduction is also examined. Restoration practices associated with this type of cooling are done through removal/reconnection of the obstacles that are necessary to allow the process of re-creating dynamic channel complexity. The observed significant reduction of summer water temperatures associated with channel complexity indicates that this approach is more flexible in reducing temperature than approaches that rely on flow increments or/and shade. Although the costs associated with the hyporheic approach are substantial, the effects of such a long-term ecological improvement of floodplain habitat may substantially benefit salmonid populations. Title: Economic analysis of restoration practices to improve water quality and fish habitat of a large river floodplain : a case study of the Willamette River, Oregon Author: Seedang, Saichon In- stream water temperature is one of the most important environmental factors associated with the decline in salmonid populations and their habitats in the Pacific Northwest. Most ecological restoration practices that attempt to reduce instream temperatures center on replanting or reestablishing riparian vegetation and increasing flows. However, in a large floodplain river like the Willamette, restoring hyporheic flow may also play an important role in reducing water temperature. The objective of this dissertation is to examine restoration practices that focus on the reduction of water temperatures in the upper mainstem Willamette River, Oregon, for the benefit of salmonid species. Economic information is developed to determine the cost-effectiveness of water temperature reduction strategies. The CEQUAL- W2 water temperature model is used to simulate the effects of upstream combinations of riparian shading and flow increments on downstream water temperatures. Costs associated with these strategies are estimated. These costs consist of the opportunity costs of losing agricultural production, and losing recreation due to flow releases from up-stream reservoirs. The effectiveness of each strategy in reducing water temperature and the associated costs are used to construct a cost-effectiveness frontier. The results indicate that the cumulative effects of shading and flows have little impact on temperature reduction downstream. Even when maximum available resources are allocated to investments in shade and flow increases they cannot lower summer water temperatures sufficiently to meet the state water temperature standard. However, the restoration practices selected from the cost-effectiveness frontiers method do provide ranges of achievable temperature reductions at minimum costs. These results are thus useful management tools when selecting policies to pursue water temperature goals. Hyporheic temperature reduction is also examined. Restoration practices associated with this type of cooling are done through removal/reconnection of the obstacles that are necessary to allow the process of re-creating dynamic channel complexity. The observed significant reduction of summer water temperatures associated with channel complexity indicates that this approach is more flexible in reducing temperature than approaches that rely on flow increments or/and shade. Although the costs associated with the hyporheic approach are substantial, the effects of such a long-term ecological improvement of floodplain habitat may substantially benefit salmonid populations. Close

• 12. [Article] Quantifying spatial differences in metabolism in headwater streams

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by The Society for Freshwater Science and published by The University of Chicago Press. ...

  Citation × Citation Citation Abstract Copy Title: Quantifying spatial differences in metabolism in headwater streams Author: Haggerty, Roy, Argerich, Alba, Gonzalez-Pinzon, Ricardo This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by The Society for Freshwater Science and published by The University of Chicago Press. It can be found at: https://www.freshwater-science.org/Journal/Access-FWS.aspx Title: Quantifying spatial differences in metabolism in headwater streams Author: Haggerty, Roy, Argerich, Alba, Gonzalez-Pinzon, Ricardo This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by The Society for Freshwater Science and published by The University of Chicago Press. It can be found at: https://www.freshwater-science.org/Journal/Access-FWS.aspx Close

• 13. [Article] Influence of hyporheic flow and geomorphology on temperature of a large, gravel-bed river, Clackamas River, Oregon, USA

  The hyporheic zone influences the thermal regime of rivers, buffering temperature by storing and releasing heat over a range of timescales. We examined the relationship between hyporheic exchange and temperature ...

  Citation × Citation Citation Abstract Copy Title: Influence of hyporheic flow and geomorphology on temperature of a large, gravel-bed river, Clackamas River, Oregon, USA Author: Burkholder, Barbara K. The hyporheic zone influences the thermal regime of rivers, buffering temperature by storing and releasing heat over a range of timescales. We examined the relationship between hyporheic exchange and temperature along a 24-km reach of the lower Clackamas River, a large gravel-bed river in northwestern Oregon (median discharge = 75.7 m³/s; minimum mean monthly discharge = 22.7 m³/s in August 2006). With a simple mixing model, we estimated how much hyporheic exchange cools the river during hot summer months. Hyporheic exchange was primarily identified by temperature anomalies, which are patches of water that demonstrate at least a 1 °C temperature difference from the main channel. Forty hyporheic temperature anomalies were identified through field investigations and TIR (Thermal-Infrared-Radiometry) in summer 2006. The location of anomalies was associated with specific geomorphic features, primarily bar channels and bar heads that act as preferential pathways for hyporheic flow. Detailed field characterization and groundwater modeling on three Clackamas gravel bars indicate residence times of hyporheic water can vary from hours to weeks and months. This was largely determined by hydraulic conductivity, which is affected by how recently the gravel bar formed or was reworked. Upscaling of modeled discharges and hydrologic parameters from these bars to the other anomalies on the Clackamas network shows that hyporheic discharge from anomalies comprises a small fraction (<< 1 %) of mainstem discharge, resulting in small river cooling effects (0.012 °C). However, the presence of cooler patches of water within rivers can act as thermal refugia for fish and other aquatic organisms, making the creation or enhancement of hyporheic exchange an attractive method in restoring the thermal regime of rivers. Title: Influence of hyporheic flow and geomorphology on temperature of a large, gravel-bed river, Clackamas River, Oregon, USA Author: Burkholder, Barbara K. The hyporheic zone influences the thermal regime of rivers, buffering temperature by storing and releasing heat over a range of timescales. We examined the relationship between hyporheic exchange and temperature along a 24-km reach of the lower Clackamas River, a large gravel-bed river in northwestern Oregon (median discharge = 75.7 m³/s; minimum mean monthly discharge = 22.7 m³/s in August 2006). With a simple mixing model, we estimated how much hyporheic exchange cools the river during hot summer months. Hyporheic exchange was primarily identified by temperature anomalies, which are patches of water that demonstrate at least a 1 °C temperature difference from the main channel. Forty hyporheic temperature anomalies were identified through field investigations and TIR (Thermal-Infrared-Radiometry) in summer 2006. The location of anomalies was associated with specific geomorphic features, primarily bar channels and bar heads that act as preferential pathways for hyporheic flow. Detailed field characterization and groundwater modeling on three Clackamas gravel bars indicate residence times of hyporheic water can vary from hours to weeks and months. This was largely determined by hydraulic conductivity, which is affected by how recently the gravel bar formed or was reworked. Upscaling of modeled discharges and hydrologic parameters from these bars to the other anomalies on the Clackamas network shows that hyporheic discharge from anomalies comprises a small fraction (<< 1 %) of mainstem discharge, resulting in small river cooling effects (0.012 °C). However, the presence of cooler patches of water within rivers can act as thermal refugia for fish and other aquatic organisms, making the creation or enhancement of hyporheic exchange an attractive method in restoring the thermal regime of rivers. Close

• 14. [Article] Redd site selection and spawning habitat use by fall chinook salmon

  The spawning habitat associated with fall chinook salmon (Oncorhynchus tshawytscha) redd clusters was investigated in the Hanford Reach of the Columbia River. A conceptual spawning habitat model is proposed ...

  Citation × Citation Citation Abstract Copy Title: Redd site selection and spawning habitat use by fall chinook salmon Author: Geist, David R. The spawning habitat associated with fall chinook salmon (Oncorhynchus tshawytscha) redd clusters was investigated in the Hanford Reach of the Columbia River. A conceptual spawning habitat model is proposed that describes how geomorphic features of river channels create hydraulic processes, including hyporheic flows, that influence where salmon spawn in unconstrained reaches of large mainstem alluvial rivers. Spatial point pattern analysis of redds showed that redd clusters averaged approximately 10 hectares in area and their locations were consistent from year to year. The tendency to spawn in clusters suggests fall chinook salmon's use of spawning habitat is highly selective. Hydraulic characteristics of the redd clusters were significantly different than the habitat surrounding them. Velocity and lateral slope of the river bottom were the most important habitat variables in predicting redd site selection. While these variables explained a large proportion of the variance in redd site selection (86 to 96%), some unmeasured factors still accounted for a small percentage of actual spawning site selection. Further investigation showed that the magnitude and chemical characteristics of hyporheic discharge were different between and within two spawning areas. Apparently, fall chinook salmon used chemical and physical cues from the discharge to locate spawning areas. Traditional spawning habitat models could be improved if they: used spawning area-specific, rather than river-specific; spawning characteristics; incorporated hyporheic discharge measurements; and gave further consideration to the geomorphic features that are present in the unconstrained segments of large alluvial rivers. Ultimately the recovery of endangered fall chinook salmon will depend on how well we are able to recreate the characteristics once common in alluvial floodplains of large rivers. The results from this research can be used to better define the relationship between these physical habitat characteristics and fall chinook salmon spawning site selection, and provide more efficient use of limited recovery resources. Title: Redd site selection and spawning habitat use by fall chinook salmon Author: Geist, David R. The spawning habitat associated with fall chinook salmon (Oncorhynchus tshawytscha) redd clusters was investigated in the Hanford Reach of the Columbia River. A conceptual spawning habitat model is proposed that describes how geomorphic features of river channels create hydraulic processes, including hyporheic flows, that influence where salmon spawn in unconstrained reaches of large mainstem alluvial rivers. Spatial point pattern analysis of redds showed that redd clusters averaged approximately 10 hectares in area and their locations were consistent from year to year. The tendency to spawn in clusters suggests fall chinook salmon's use of spawning habitat is highly selective. Hydraulic characteristics of the redd clusters were significantly different than the habitat surrounding them. Velocity and lateral slope of the river bottom were the most important habitat variables in predicting redd site selection. While these variables explained a large proportion of the variance in redd site selection (86 to 96%), some unmeasured factors still accounted for a small percentage of actual spawning site selection. Further investigation showed that the magnitude and chemical characteristics of hyporheic discharge were different between and within two spawning areas. Apparently, fall chinook salmon used chemical and physical cues from the discharge to locate spawning areas. Traditional spawning habitat models could be improved if they: used spawning area-specific, rather than river-specific; spawning characteristics; incorporated hyporheic discharge measurements; and gave further consideration to the geomorphic features that are present in the unconstrained segments of large alluvial rivers. Ultimately the recovery of endangered fall chinook salmon will depend on how well we are able to recreate the characteristics once common in alluvial floodplains of large rivers. The results from this research can be used to better define the relationship between these physical habitat characteristics and fall chinook salmon spawning site selection, and provide more efficient use of limited recovery resources. Close

• 15. [Article] Surface Water and Groundwater Interactions in the Walla Walla River, Northeast Oregon, USA : A Multi-Method Field-Based Approach

  Surface water and groundwater interactions are a key component in the functioning of stream ecosystems. Exchange of water between the stream and the hyporheic zone creates habitat for aquatic organisms ...

  Citation × Citation Citation Abstract Copy Title: Surface Water and Groundwater Interactions in the Walla Walla River, Northeast Oregon, USA : A Multi-Method Field-Based Approach Author: Gryczkowski, Landon Surface water and groundwater interactions are a key component in the functioning of stream ecosystems. Exchange of water between the stream and the hyporheic zone creates habitat for aquatic organisms and serves as a control for stream biogeochemical, thermal, and flow processes. This study takes a multi-method field-based approach to gain a better understanding of exchange processes in the Walla Walla River, Northeast Oregon, USA, with focus on advancing methodologies, spatial and temporal exchange dynamics, fish ecology and habitat, and geomorphic controls on hyporheic exchange. Fiber-optic distributed temperature sensing (DTS) was used to identify, quantify, and map cold-water inflows at the meter scale. Analysis of the maximum and minimum daily temperature traces separated each cold-water inflow into either hyporheic or groundwater-derived. DTS identified a very active hyporheic zone in this system, with a near-equal importance of hyporheic and groundwater inflows. Approximately one-third of the 2-km study reach was influence by cold-water inflows, providing significant cooling in certain areas. Using piezometers in conjunction with DTS provided validation and supplementation of DTS results, increased the reliability of conclusions, and helped to identify and understand specific exchange processes. Piezometer data showed downwelling conditions (negative head differential) except immediately downstream of riffles, with head differentials becoming increasingly negative farther downstream from a riffle. Furthermore, head differentials increased in the negative direction from left bank to right bank, indicating lateral movement of groundwater and more loss of river water from the right bank. Nearest to riffles and river bends, head differentials remained more stable over time, which may indicate that geomorphic structures influence head variations locally, while aquifer levels and dynamics have an increasing influence farther from these structures. Seasonally, head differentials became increasingly negative through the summer into fall as aquifer levels decreased, and areas of the river that lost the most water to the subsurface tended to lose more water at a faster rate as the summer progressed. However, the seasonal trend of head differentials may be counteracted by decreasing bed permeability, yielding little or no temporal change in vertical flux of water through the streambed. During high-flow events, river losses to the subsurface decreased overall; in particular, areas with the greatest water loss at low flows showed reduced losses during high flows. High variability and lack of patterns in the response to high flow events suggests complexity in this process. Temperature-related variables from DTS data were combined with habitat-related variables to determine which variables best explain pool-scale salmonid abundance. Two snorkel surveys of 23 pools within the study reach were performed. The change in temperature across the pool showed the strongest overall relationship to salmonid abundance, particularly Chinook salmon. Chinook salmon showed a stronger preference for specific pools compared to steelhead/rainbow trout. The magnitude of cold-water inflows appears more important than the presence or proportion of the pool receiving cold-water inflows, and salmonid abundance was more strongly explained by hyporheic inflows compared to groundwater. Temperature variables increased in importance relative to habitat variables in the second snorkel sample compared to sample one. The highest river temperatures of the summer occurred between the two sample dates, and this may suggest that salmonids’ affinity for cold-water refuge was enhanced through behavioral adaptation following periods of high temperature approaching the lethal threshold. The combined use of DTS, continuous electrical resistivity/induced polarization profiling, LiDAR, aerial imagery analysis, and field surveys allowed for the quantification of many geomorphic and hydraulic variables known or hypothesized to contribute to surface water and groundwater exchange processes. Regression analysis was used to determine which of these variables best explain the presence and magnitude of both groundwater and hyporheic inflows. For the first time, the cross-sectional area of the hyporheic zone was estimated at high resolution at the reach scale, and decreasing hyporheic cross-sectional area best explained both the presence and magnitude of cold-water inflows of either type. Higher water surface slope and sinuosity/curvature were next in order of importance. The presence of hyporheic inflows was also explained by higher water surface slope, sinuosity, and Reynolds number, while the magnitude of hyporheic inflows was best explained by higher sinuosity. Groundwater inflows were also explained by higher width-to-depth ratio, higher water surface slope, decreasing distance from a stream bank to the bankfull or floodplain extent, and decreasing flow velocity. Lateral processes (e.g. sinuosity) and vertical processes (e.g. water surface slope) were found to be of comparable importance, but lateral processes better explained larger decreases in stream temperature, possibly because lateral subsurface flow paths are longer in distance and duration. Hydraulic conductivity variables did not show up among the most important variables likely because of the difficulty in estimating hydraulic conductivity at the meter scale using electrical geophysical tools. Title: Surface Water and Groundwater Interactions in the Walla Walla River, Northeast Oregon, USA : A Multi-Method Field-Based Approach Author: Gryczkowski, Landon Surface water and groundwater interactions are a key component in the functioning of stream ecosystems. Exchange of water between the stream and the hyporheic zone creates habitat for aquatic organisms and serves as a control for stream biogeochemical, thermal, and flow processes. This study takes a multi-method field-based approach to gain a better understanding of exchange processes in the Walla Walla River, Northeast Oregon, USA, with focus on advancing methodologies, spatial and temporal exchange dynamics, fish ecology and habitat, and geomorphic controls on hyporheic exchange. Fiber-optic distributed temperature sensing (DTS) was used to identify, quantify, and map cold-water inflows at the meter scale. Analysis of the maximum and minimum daily temperature traces separated each cold-water inflow into either hyporheic or groundwater-derived. DTS identified a very active hyporheic zone in this system, with a near-equal importance of hyporheic and groundwater inflows. Approximately one-third of the 2-km study reach was influence by cold-water inflows, providing significant cooling in certain areas. Using piezometers in conjunction with DTS provided validation and supplementation of DTS results, increased the reliability of conclusions, and helped to identify and understand specific exchange processes. Piezometer data showed downwelling conditions (negative head differential) except immediately downstream of riffles, with head differentials becoming increasingly negative farther downstream from a riffle. Furthermore, head differentials increased in the negative direction from left bank to right bank, indicating lateral movement of groundwater and more loss of river water from the right bank. Nearest to riffles and river bends, head differentials remained more stable over time, which may indicate that geomorphic structures influence head variations locally, while aquifer levels and dynamics have an increasing influence farther from these structures. Seasonally, head differentials became increasingly negative through the summer into fall as aquifer levels decreased, and areas of the river that lost the most water to the subsurface tended to lose more water at a faster rate as the summer progressed. However, the seasonal trend of head differentials may be counteracted by decreasing bed permeability, yielding little or no temporal change in vertical flux of water through the streambed. During high-flow events, river losses to the subsurface decreased overall; in particular, areas with the greatest water loss at low flows showed reduced losses during high flows. High variability and lack of patterns in the response to high flow events suggests complexity in this process. Temperature-related variables from DTS data were combined with habitat-related variables to determine which variables best explain pool-scale salmonid abundance. Two snorkel surveys of 23 pools within the study reach were performed. The change in temperature across the pool showed the strongest overall relationship to salmonid abundance, particularly Chinook salmon. Chinook salmon showed a stronger preference for specific pools compared to steelhead/rainbow trout. The magnitude of cold-water inflows appears more important than the presence or proportion of the pool receiving cold-water inflows, and salmonid abundance was more strongly explained by hyporheic inflows compared to groundwater. Temperature variables increased in importance relative to habitat variables in the second snorkel sample compared to sample one. The highest river temperatures of the summer occurred between the two sample dates, and this may suggest that salmonids’ affinity for cold-water refuge was enhanced through behavioral adaptation following periods of high temperature approaching the lethal threshold. The combined use of DTS, continuous electrical resistivity/induced polarization profiling, LiDAR, aerial imagery analysis, and field surveys allowed for the quantification of many geomorphic and hydraulic variables known or hypothesized to contribute to surface water and groundwater exchange processes. Regression analysis was used to determine which of these variables best explain the presence and magnitude of both groundwater and hyporheic inflows. For the first time, the cross-sectional area of the hyporheic zone was estimated at high resolution at the reach scale, and decreasing hyporheic cross-sectional area best explained both the presence and magnitude of cold-water inflows of either type. Higher water surface slope and sinuosity/curvature were next in order of importance. The presence of hyporheic inflows was also explained by higher water surface slope, sinuosity, and Reynolds number, while the magnitude of hyporheic inflows was best explained by higher sinuosity. Groundwater inflows were also explained by higher width-to-depth ratio, higher water surface slope, decreasing distance from a stream bank to the bankfull or floodplain extent, and decreasing flow velocity. Lateral processes (e.g. sinuosity) and vertical processes (e.g. water surface slope) were found to be of comparable importance, but lateral processes better explained larger decreases in stream temperature, possibly because lateral subsurface flow paths are longer in distance and duration. Hydraulic conductivity variables did not show up among the most important variables likely because of the difficulty in estimating hydraulic conductivity at the meter scale using electrical geophysical tools. Close

• 16. [Article] Heat balance of alcoves on the Willamette River, Oregon.

  Alcoves in some river systems are cooler than the mainstem of the river and provide thermal refugia for aquatic species. An energy balance and sensitivity analysis on 3 alcoves in the Willamette River, ...

  Citation × Citation Citation Abstract Copy Title: Heat balance of alcoves on the Willamette River, Oregon. Author: Bryenton, Andrew G. Alcoves in some river systems are cooler than the mainstem of the river and provide thermal refugia for aquatic species. An energy balance and sensitivity analysis on 3 alcoves in the Willamette River, Oregon indicate that alcove size and alcove flux determine the degree to which meteorological conditions affect the alcove water temperature. Large alcoves with a low alcove flux and large surface area are more sensitive to meteorological conditions (i.e., shade and wind). Small alcoves with a high alcove flux and small surface area are more sensitive to the temperature of emerging subsurface water than to meteorological conditions. The temperature of hyporheic water relative to the mainstem is determined by its residence time; longer flow paths disperse the diurnal signal and move hyporheic water into equilibrium with mean seasonal or annual subsurface temperatures. Floodplain restoration may increase alcove population in a river system thereby making it a potential credit trading tool for mitigating excess thermal loading in a heat stressed river. Title: Heat balance of alcoves on the Willamette River, Oregon. Author: Bryenton, Andrew G. Alcoves in some river systems are cooler than the mainstem of the river and provide thermal refugia for aquatic species. An energy balance and sensitivity analysis on 3 alcoves in the Willamette River, Oregon indicate that alcove size and alcove flux determine the degree to which meteorological conditions affect the alcove water temperature. Large alcoves with a low alcove flux and large surface area are more sensitive to meteorological conditions (i.e., shade and wind). Small alcoves with a high alcove flux and small surface area are more sensitive to the temperature of emerging subsurface water than to meteorological conditions. The temperature of hyporheic water relative to the mainstem is determined by its residence time; longer flow paths disperse the diurnal signal and move hyporheic water into equilibrium with mean seasonal or annual subsurface temperatures. Floodplain restoration may increase alcove population in a river system thereby making it a potential credit trading tool for mitigating excess thermal loading in a heat stressed river. Close

• 17. [Article] Bryenton, A_Thesis.pdf

  Citation × Citation Citation Abstract Copy Title: Bryenton, A_Thesis.pdf Author: Bryenton, Andrew G. Title: Bryenton, A_Thesis.pdf Author: Bryenton, Andrew G. Close

• 18. [Article] Appendix_E.zip

  Citation × Citation Citation Abstract Copy Title: Appendix_E.zip Author: Bryenton, Andrew G. Title: Appendix_E.zip Author: Bryenton, Andrew G. Close

• 19. [Article] Changes in hyporheic exchange flow following experimental large wood removal in a second order, low gradient stream, Chichagof Island, AK

  Hyporheic Exchange Flow (HEF) is driven by head gradients defined by the hydro-topography of the stream surface, which is controlled by the particular geomorphology of the stream. We quantified the impact ...

  Citation × Citation Citation Abstract Copy Title: Changes in hyporheic exchange flow following experimental large wood removal in a second order, low gradient stream, Chichagof Island, AK Author: La Nier, Justin Hyporheic Exchange Flow (HEF) is driven by head gradients defined by the hydro-topography of the stream surface, which is controlled by the particular geomorphology of the stream. We quantified the impact of large wood, which typically exerts a strong control on stream morphology, on HEF in a second order, low gradient (~1%), coastal Alaskan stream. Experimental removal of large wood (> 10 cm diameter) from Bambi Creek, a second order stream on Chichagof Island, AK demonstrated that the wood-forced pool-riffle morphology transitions to that of alternating pool-riffle sequences, and led to an increase in sediment stored in the reach (Smith et al., 1993). We constructed a series of five groundwater flow models (MODFLOW) spanning 16 years to examine the response of HEF, and we used particle tracking (MODPATH) to examine changes to the flow paths and residence times. Changes in the pattern of hyporheic upwelling and downwelling generally correspond to changes in the local hydro-topography over the five study periods and generally corresponded to locations of large wood removal. Reach total hyporheic exchange decreased from 0.96 to 0.87 L/s during loss of sediment storage, then increased to 1.22 L/s and again to 1.90 L/s for periods when sediment storage increased in the reach. The turnover length of hyporheic exchange for baseflow conditions decreased from 4.5 km to 2.3 km. The area of the streambed contributing to hyporheic flux increased over the study period, as well as the amount of hyporheic flow across meander bends. The median residence time of the hyporheic flowpaths increased from 8 to 11 hours by 4-years post removal then again to 14 hours by 16-years post-removal. Changes in the residence time probability and cumulative density functions for the models show an increase in late time portion of these functions at 4 years and 16 years post removal. The change in channel morphology from wood-forced pool-riffle to that of alternating pool-riffle sequences apparently increased the amount of hyporheic exchange. Title: Changes in hyporheic exchange flow following experimental large wood removal in a second order, low gradient stream, Chichagof Island, AK Author: La Nier, Justin Hyporheic Exchange Flow (HEF) is driven by head gradients defined by the hydro-topography of the stream surface, which is controlled by the particular geomorphology of the stream. We quantified the impact of large wood, which typically exerts a strong control on stream morphology, on HEF in a second order, low gradient (~1%), coastal Alaskan stream. Experimental removal of large wood (> 10 cm diameter) from Bambi Creek, a second order stream on Chichagof Island, AK demonstrated that the wood-forced pool-riffle morphology transitions to that of alternating pool-riffle sequences, and led to an increase in sediment stored in the reach (Smith et al., 1993). We constructed a series of five groundwater flow models (MODFLOW) spanning 16 years to examine the response of HEF, and we used particle tracking (MODPATH) to examine changes to the flow paths and residence times. Changes in the pattern of hyporheic upwelling and downwelling generally correspond to changes in the local hydro-topography over the five study periods and generally corresponded to locations of large wood removal. Reach total hyporheic exchange decreased from 0.96 to 0.87 L/s during loss of sediment storage, then increased to 1.22 L/s and again to 1.90 L/s for periods when sediment storage increased in the reach. The turnover length of hyporheic exchange for baseflow conditions decreased from 4.5 km to 2.3 km. The area of the streambed contributing to hyporheic flux increased over the study period, as well as the amount of hyporheic flow across meander bends. The median residence time of the hyporheic flowpaths increased from 8 to 11 hours by 4-years post removal then again to 14 hours by 16-years post-removal. Changes in the residence time probability and cumulative density functions for the models show an increase in late time portion of these functions at 4 years and 16 years post removal. The change in channel morphology from wood-forced pool-riffle to that of alternating pool-riffle sequences apparently increased the amount of hyporheic exchange. Close

• 20. [Article] Monitoring river restoration using fiber optic temperature measurements in a modeling framework

  The Middle Fork of the John Day River (MFJD) in Northeastern Oregon contains important spawning grounds for spring Chinook and summer steelhead of the Columbia River Basin. In the summer of 2008 phase ...

  Citation × Citation Citation Abstract Copy Title: Monitoring river restoration using fiber optic temperature measurements in a modeling framework Author: Huff, Julie A. The Middle Fork of the John Day River (MFJD) in Northeastern Oregon contains important spawning grounds for spring Chinook and summer steelhead of the Columbia River Basin. In the summer of 2008 phase one of a river restoration project was completed which included the addition of engineered log jams (ELJs) and scour pools. The restoration focuses on increasing habitat diversity and decreasing peak summer temperatures which, perhaps, had been degraded due to anthropogenic activities such as dredge mining, cattle grazing, channelization and deforestation. This study utilized Distributed Temperature Sensing (DTS) technology to measure the temperature the MFJD study site before and after restoration during the summer of 2008. The temperature data along with other physical and climatic data were modeled using a physically based stream temperature model which incorporated groundwater inflows and an average depth of hyporheic exchange over the entire study reach. The root mean square errors for the pre- and post-restoration model are 0.57°C and 0.47°C, respectively. An average depth of the thermal mass associated with hyporheic exchange was calculated within the model to be 11m for pre- restoration and 1.6m for post-restoration. It is unclear as to whether the hyporheic exchange increased due to restoration or is an artifact of high flows during the pre-restoration period. A statistical analysis was completed on the longitudinal temperature profiles of the MFJD to identify lengths of the river whose temperatures are different upstream and downstream. Groundwater inflow was defined as locations with cooler day time and night time temperatures than the surroundings whereas hyporheic discharge was defined as locations with cooler day time temperatures but warmer night time temperature than the surroundings. Statistically significant locations were highlighted for both pre- and post-restoration and equated to an average decrease in local temperature of 0.08°C pre-restoration and 1.18°C post-restoration. This equates to 0.004 m³/s and 0.012 m³/s of groundwater inflow for pre- and post-restoration, respectively. Again, these differences could be artifacts of high flows during pre-restoration and cannot conclusively be linked to the restoration efforts. However, the largest groundwater inflow (0.004 m³/s) can be associated with one ELJ structure and its corresponding scour pool. Title: Monitoring river restoration using fiber optic temperature measurements in a modeling framework Author: Huff, Julie A. The Middle Fork of the John Day River (MFJD) in Northeastern Oregon contains important spawning grounds for spring Chinook and summer steelhead of the Columbia River Basin. In the summer of 2008 phase one of a river restoration project was completed which included the addition of engineered log jams (ELJs) and scour pools. The restoration focuses on increasing habitat diversity and decreasing peak summer temperatures which, perhaps, had been degraded due to anthropogenic activities such as dredge mining, cattle grazing, channelization and deforestation. This study utilized Distributed Temperature Sensing (DTS) technology to measure the temperature the MFJD study site before and after restoration during the summer of 2008. The temperature data along with other physical and climatic data were modeled using a physically based stream temperature model which incorporated groundwater inflows and an average depth of hyporheic exchange over the entire study reach. The root mean square errors for the pre- and post-restoration model are 0.57°C and 0.47°C, respectively. An average depth of the thermal mass associated with hyporheic exchange was calculated within the model to be 11m for pre- restoration and 1.6m for post-restoration. It is unclear as to whether the hyporheic exchange increased due to restoration or is an artifact of high flows during the pre-restoration period. A statistical analysis was completed on the longitudinal temperature profiles of the MFJD to identify lengths of the river whose temperatures are different upstream and downstream. Groundwater inflow was defined as locations with cooler day time and night time temperatures than the surroundings whereas hyporheic discharge was defined as locations with cooler day time temperatures but warmer night time temperature than the surroundings. Statistically significant locations were highlighted for both pre- and post-restoration and equated to an average decrease in local temperature of 0.08°C pre-restoration and 1.18°C post-restoration. This equates to 0.004 m³/s and 0.012 m³/s of groundwater inflow for pre- and post-restoration, respectively. Again, these differences could be artifacts of high flows during pre-restoration and cannot conclusively be linked to the restoration efforts. However, the largest groundwater inflow (0.004 m³/s) can be associated with one ELJ structure and its corresponding scour pool. Close