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• 11. [Article] Impacts of Water Level Rise on Algal Bloom Prevention in the Tributary of Three Gorges Reservoir, China

  Water level fluctuation plays an important role in algal blooms within the side arms. Field observations of the impacts of fluctuations of water level in Xiangxi Bay (XXB), one of the tributaries of the ...

  Citation × Citation Citation Abstract Copy Title: Impacts of Water Level Rise on Algal Bloom Prevention in the Tributary of Three Gorges Reservoir, China Author: Ji, Daobin, Wells, Scott A., Yang, Zhengjian, Liu, Defu Year: 2017 Water level fluctuation plays an important role in algal blooms within the side arms. Field observations of the impacts of fluctuations of water level in Xiangxi Bay (XXB), one of the tributaries of the TGR, were analyzed from 2008 to 2010. Water level rise can result in increases as well as decreases in Chl. a, which depends on the water circulation patterns in the XXB. Those effective/ineffective water circulation patterns in preventing algal blooms in the XXB were based on the tributary inflow but also from the intrusion flow from the TGR. Flow velocity, thermal structure, hydrodynamic characteristics including water age, the turbulent eddy viscosity, the buoyancy frequency, the mixing depth, and the ratio of the euphotic depth and the mixed layer depth were evaluated for these scenarios. It is showed that the effective water circulation patterns in the XXB occurred when there was a converging of the inflow from the upstream with an intrusive overflow, lower-interflow, underflow or the combination from the TGR mainstream. Larger daily WL fluctuation and a longer duration of WL rise would enhance algal bloom prevention in the XXB. These results can provide assistance in managing the operation of water levels in TGR. © 2016 Elsevier B.V. Title: Impacts of Water Level Rise on Algal Bloom Prevention in the Tributary of Three Gorges Reservoir, China Author: Ji, Daobin, Wells, Scott A., Yang, Zhengjian, Liu, Defu Year: 2017 Water level fluctuation plays an important role in algal blooms within the side arms. Field observations of the impacts of fluctuations of water level in Xiangxi Bay (XXB), one of the tributaries of the TGR, were analyzed from 2008 to 2010. Water level rise can result in increases as well as decreases in Chl. a, which depends on the water circulation patterns in the XXB. Those effective/ineffective water circulation patterns in preventing algal blooms in the XXB were based on the tributary inflow but also from the intrusion flow from the TGR. Flow velocity, thermal structure, hydrodynamic characteristics including water age, the turbulent eddy viscosity, the buoyancy frequency, the mixing depth, and the ratio of the euphotic depth and the mixed layer depth were evaluated for these scenarios. It is showed that the effective water circulation patterns in the XXB occurred when there was a converging of the inflow from the upstream with an intrusive overflow, lower-interflow, underflow or the combination from the TGR mainstream. Larger daily WL fluctuation and a longer duration of WL rise would enhance algal bloom prevention in the XXB. These results can provide assistance in managing the operation of water levels in TGR. © 2016 Elsevier B.V. Close

• 12. [Article] Modeling Density Currents in Circular Clarifiers

  Design of sedimentation tanks for solid-liquid separation is often dependent on assuming ideal flow conditions. But the geometry of the tank and density currents as a result of temperature and suspended ...

  Citation × Citation Citation Abstract Copy Title: Modeling Density Currents in Circular Clarifiers Author: Wells, Scott A., LaLiberte, David M. Year: 1998 Design of sedimentation tanks for solid-liquid separation is often dependent on assuming ideal flow conditions. But the geometry of the tank and density currents as a result of temperature and suspended solids influences the fluid mechanics of the tank and can result in significant deviations from ideal flow. A two-dimensional radial flow model was proposed which incorporated the effect of density currents resulting from temperature and suspended solids differentials within the tank. The numerical model predicted the steady-state, layer-averaged radial flow and layer depth. The model solution and field data showed that the momentum and suspended solids of the inflow caused a density current that moved along the clarifier bottom. In the winter, this density current rose as a result of warm inflow water after the initial momentum had decreased and the suspended solids had settled. Title: Modeling Density Currents in Circular Clarifiers Author: Wells, Scott A., LaLiberte, David M. Year: 1998 Design of sedimentation tanks for solid-liquid separation is often dependent on assuming ideal flow conditions. But the geometry of the tank and density currents as a result of temperature and suspended solids influences the fluid mechanics of the tank and can result in significant deviations from ideal flow. A two-dimensional radial flow model was proposed which incorporated the effect of density currents resulting from temperature and suspended solids differentials within the tank. The numerical model predicted the steady-state, layer-averaged radial flow and layer depth. The model solution and field data showed that the momentum and suspended solids of the inflow caused a density current that moved along the clarifier bottom. In the winter, this density current rose as a result of warm inflow water after the initial momentum had decreased and the suspended solids had settled. Close

• 13. [Article] Estimation of Surface Water Temperature of the Tigris River System in Iraq

  Monitoring surface water temperatures (Tw) in lakes, rivers, and reservoirs is a key component of environmental management and influences water quality by affecting bio-geo chemical reaction rates, altering ...

  Citation × Citation Citation Abstract Copy Title: Estimation of Surface Water Temperature of the Tigris River System in Iraq Author: Al-Murib, M., Wells, Scott A., Talke, Stefan A. Year: 2017 Monitoring surface water temperatures (Tw) in lakes, rivers, and reservoirs is a key component of environmental management and influences water quality by affecting bio-geo chemical reaction rates, altering the saturation concentration of dissolved oxygen (DO), and influencing the susceptibility of fish to disease. Temperatures in the Tigris River, one of the largest rivers in the Middle East, are influenced by factors such as heat fluxes at the air-water and human activities such as direct discharge of water to the river. However, modeling and management of water temperature is limited by a paucity of in-situ data, which prevents calibration of models. In this study, we infill data gaps by estimating Tw using the thermal bands of both the Landsat 5 TM and Landsat 7 ETM+ sensors. These satellite-based estimates, typically measured once or twice a month with 60-120m resolution, are then used to develop a regression model that relates daily water temperature to daily air temperature and river flow. These estimates are used to define the Tw boundary conditions for a hydrodynamic and water quality model of the Tigris River based on a 2D implementation of the CE-QUAL-W2 (W2) numerical model. Initial results suggest that there is a significant agreement between modeled and remotely estimated data of Tw. Results suggest that short-wave solar radiation is the most important factor that controls seasonal Tw variations. However, anthropogenic influence is observed as a result of return irrigation flows and flows from Tharthar Lake. Title: Estimation of Surface Water Temperature of the Tigris River System in Iraq Author: Al-Murib, M., Wells, Scott A., Talke, Stefan A. Year: 2017 Monitoring surface water temperatures (Tw) in lakes, rivers, and reservoirs is a key component of environmental management and influences water quality by affecting bio-geo chemical reaction rates, altering the saturation concentration of dissolved oxygen (DO), and influencing the susceptibility of fish to disease. Temperatures in the Tigris River, one of the largest rivers in the Middle East, are influenced by factors such as heat fluxes at the air-water and human activities such as direct discharge of water to the river. However, modeling and management of water temperature is limited by a paucity of in-situ data, which prevents calibration of models. In this study, we infill data gaps by estimating Tw using the thermal bands of both the Landsat 5 TM and Landsat 7 ETM+ sensors. These satellite-based estimates, typically measured once or twice a month with 60-120m resolution, are then used to develop a regression model that relates daily water temperature to daily air temperature and river flow. These estimates are used to define the Tw boundary conditions for a hydrodynamic and water quality model of the Tigris River based on a 2D implementation of the CE-QUAL-W2 (W2) numerical model. Initial results suggest that there is a significant agreement between modeled and remotely estimated data of Tw. Results suggest that short-wave solar radiation is the most important factor that controls seasonal Tw variations. However, anthropogenic influence is observed as a result of return irrigation flows and flows from Tharthar Lake. Close

• 14. [Article] Amaila Falls Hydroelectric Project Model Development and Scenarios

  The focus of this present study is to perform the following tasks: * Develop a hydrodynamic and water quality model of the reservoir formed by the Amaila Falls Hydroelectric Project * Develop and run modeling ...

  Citation × Citation Citation Abstract Copy Title: Amaila Falls Hydroelectric Project Model Development and Scenarios Author: Berger, Chris, Wells, Scott A., Wells, Vanessa Year: 2010 The focus of this present study is to perform the following tasks: * Develop a hydrodynamic and water quality model of the reservoir formed by the Amaila Falls Hydroelectric Project * Develop and run modeling scenarios Water quality model simulations of the 23.3 km2 reservoir for Amaila Falls Hydroelectric Project were conducted for low, average, and high flow years. A scenario with no vegetation removed from the reservoir for an average flow was also simulated. Conditions downstream of the reservoir were also modeled using a river model. The model used for the reservoir formed by Amaila Falls Hydroelectric Project is the public domain model, CE-QUAL-W2. Title: Amaila Falls Hydroelectric Project Model Development and Scenarios Author: Berger, Chris, Wells, Scott A., Wells, Vanessa Year: 2010 The focus of this present study is to perform the following tasks: * Develop a hydrodynamic and water quality model of the reservoir formed by the Amaila Falls Hydroelectric Project * Develop and run modeling scenarios Water quality model simulations of the 23.3 km2 reservoir for Amaila Falls Hydroelectric Project were conducted for low, average, and high flow years. A scenario with no vegetation removed from the reservoir for an average flow was also simulated. Conditions downstream of the reservoir were also modeled using a river model. The model used for the reservoir formed by Amaila Falls Hydroelectric Project is the public domain model, CE-QUAL-W2. Close

• 15. [Article] Validation of the CE-QUAL-W2 Version 3 River Basin Hydrodynamic and Water Quality Model

  CE-QUAL-W2 Version 3, a 2-D (longitudinal-vertical) hydrodynamic and water quality model for river basins combining both river and stratified river-estuary and lakereservoir flow, is a development product ...

  Citation × Citation Citation Abstract Copy Title: Validation of the CE-QUAL-W2 Version 3 River Basin Hydrodynamic and Water Quality Model Author: Wells, Scott A. Year: 2002 CE-QUAL-W2 Version 3, a 2-D (longitudinal-vertical) hydrodynamic and water quality model for river basins combining both river and stratified river-estuary and lakereservoir flow, is a development product of the Waterways Experiment Station in Vicksburg, MS, USA. With the development and release of any revised or reformulated model codes, significant model validation is required. This includes comparison of model results to simple analytical solutions for hydrodynamics and water quality transport, as well as comparison to laboratory and field data. In this paper, the model is compared to numerous analytical solutions for mass transport (1-D advective mass transport) and hydrodynamics (impulsive wind stress on water surface, seiching). Suggestions are presented for proper validation protocols for hydrodynamic and water quality models. Title: Validation of the CE-QUAL-W2 Version 3 River Basin Hydrodynamic and Water Quality Model Author: Wells, Scott A. Year: 2002 CE-QUAL-W2 Version 3, a 2-D (longitudinal-vertical) hydrodynamic and water quality model for river basins combining both river and stratified river-estuary and lakereservoir flow, is a development product of the Waterways Experiment Station in Vicksburg, MS, USA. With the development and release of any revised or reformulated model codes, significant model validation is required. This includes comparison of model results to simple analytical solutions for hydrodynamics and water quality transport, as well as comparison to laboratory and field data. In this paper, the model is compared to numerous analytical solutions for mass transport (1-D advective mass transport) and hydrodynamics (impulsive wind stress on water surface, seiching). Suggestions are presented for proper validation protocols for hydrodynamic and water quality models. Close

• 16. [Article] Basis of the CE-QUAL-W2 Version 3 River Basin Hydrodynamic and Water Quality Model

  CE-QUAL-W2 Version 3, a 2-D (longitudinal-vertical) hydrodynamic and water quality model for river basins combining both river and stratified river-estuary and lake-reservoir flow, is a development product ...

  Citation × Citation Citation Abstract Copy Title: Basis of the CE-QUAL-W2 Version 3 River Basin Hydrodynamic and Water Quality Model Author: Wells, Scott A. Year: 2002 CE-QUAL-W2 Version 3, a 2-D (longitudinal-vertical) hydrodynamic and water quality model for river basins combining both river and stratified river-estuary and lake-reservoir flow, is a development product of the Waterways Experiment Station in Vicksburg, MS, USA. With the development and release of any revised or reformulated model codes, significant model validation is required. This includes comparison of model results to simple analytical solutions for hydrodynamics and water quality transport, as well as comparison to laboratory and field data. In this paper, the model is compared to numerous analytical solutions for mass transport (1- D advective mass transport) and hydrodynamics (impulsive wind stress on water surface, seiching). Suggestions are presented for proper validation protocols for hydrodynamic and water quality models. Title: Basis of the CE-QUAL-W2 Version 3 River Basin Hydrodynamic and Water Quality Model Author: Wells, Scott A. Year: 2002 CE-QUAL-W2 Version 3, a 2-D (longitudinal-vertical) hydrodynamic and water quality model for river basins combining both river and stratified river-estuary and lake-reservoir flow, is a development product of the Waterways Experiment Station in Vicksburg, MS, USA. With the development and release of any revised or reformulated model codes, significant model validation is required. This includes comparison of model results to simple analytical solutions for hydrodynamics and water quality transport, as well as comparison to laboratory and field data. In this paper, the model is compared to numerous analytical solutions for mass transport (1- D advective mass transport) and hydrodynamics (impulsive wind stress on water surface, seiching). Suggestions are presented for proper validation protocols for hydrodynamic and water quality models. Close

• 17. [Article] TMDLS: Statistical Correlations or Mechanistic Modeling?

  Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach ...

  Citation × Citation Citation Abstract Copy Title: TMDLS: Statistical Correlations or Mechanistic Modeling? Author: Wells, Scott A., Cole, Thomas M. Year: 2002 Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach and a mechanistic modeling approach. The system included the Lower Snake River, Brownlee Reservoir, Oxbow Reservoir, and Hells Canyon Reservoir with the focus was on Brownlee Reservoir. The statistical approach used on Brownlee Reservoir divided the system into riverine and lacustrine zones. Field data were then averaged over season and location to provide statistical correlations, such as between total phosphorus (TP) and chlorophyll a (chl a), between an anoxic factor (AF) and TP, and between a hypoxic factor (HP) and TP. The anoxic factor is defined as the number of days when dissolved oxygen was less than 2 mg/l and the hypoxic factor was defined as the number of days when dissolved oxygen was less than 6.5 mg/l. The mechanistic approach used a two-dimensional, unsteady, hydrodynamic and water quality model called CE-QUAL-W2. The model was calibrated to field data over a three year period for 1992 (a low flow year), 1995 (an average flow year), and 1997 (a high flow year). Some of the important questions that the TMDL process was to answer included the following. What level of TP is necessary in the river coming into Brownlee Reservoir to reduce the number of days of hypoxia in the reservoir? What are the causes of low2 dissolved oxygen in Brownlee Reservoir and what management strategies can be implemented to improve water quality? This paper examines the strengths and weaknesses of answering management questions using these two approaches. Recommendations are suggested for answering assimilative capacity questions that arise in TMDL studies. Title: TMDLS: Statistical Correlations or Mechanistic Modeling? Author: Wells, Scott A., Cole, Thomas M. Year: 2002 Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach and a mechanistic modeling approach. The system included the Lower Snake River, Brownlee Reservoir, Oxbow Reservoir, and Hells Canyon Reservoir with the focus was on Brownlee Reservoir. The statistical approach used on Brownlee Reservoir divided the system into riverine and lacustrine zones. Field data were then averaged over season and location to provide statistical correlations, such as between total phosphorus (TP) and chlorophyll a (chl a), between an anoxic factor (AF) and TP, and between a hypoxic factor (HP) and TP. The anoxic factor is defined as the number of days when dissolved oxygen was less than 2 mg/l and the hypoxic factor was defined as the number of days when dissolved oxygen was less than 6.5 mg/l. The mechanistic approach used a two-dimensional, unsteady, hydrodynamic and water quality model called CE-QUAL-W2. The model was calibrated to field data over a three year period for 1992 (a low flow year), 1995 (an average flow year), and 1997 (a high flow year). Some of the important questions that the TMDL process was to answer included the following. What level of TP is necessary in the river coming into Brownlee Reservoir to reduce the number of days of hypoxia in the reservoir? What are the causes of low2 dissolved oxygen in Brownlee Reservoir and what management strategies can be implemented to improve water quality? This paper examines the strengths and weaknesses of answering management questions using these two approaches. Recommendations are suggested for answering assimilative capacity questions that arise in TMDL studies. Close

• 18. [Article] Green River CE-QUAL-W2 Project: A Hydrodynamic and Water Quality Study of the Green River King County, Washington

  This report describes the data processing and model calibration performed for a hydrodynamic and water quality model of the Green River, located in King County, Washington. Figure 1 shows the location ...

  Citation × Citation Citation Abstract Copy Title: Green River CE-QUAL-W2 Project: A Hydrodynamic and Water Quality Study of the Green River King County, Washington Author: Kraft, Tim, Annear, Robert Leslie, Berger, Chris, Wells, Scott A. Year: 2004 This report describes the data processing and model calibration performed for a hydrodynamic and water quality model of the Green River, located in King County, Washington. Figure 1 shows the location of the river, and the limits of the section of river that was modeled. The Green River flows from its headwaters in the Cascade Mountain foothills through the King County, Washington communities of Auburn, Kent, and Tukwila before discharging into the Duwamish River. Two sections of the river were modeled in this project. The Middle Green River begins in the Cascade Mountain foothills east of Tacoma, and continues downstream to the city of Auburn, WA. The Lower Green River continues from Auburn to the confluence with the Duwamish River, in the town of Tukwila. The Green/Duwamish River system is unique in that it flows through a heavily urbanized and industrialized environment yet supports a large salmon population (Green/Duwamish Ecosystem Restoration Study, 2003). To protect the river and its prime salmon habitat, King County and the US Army Corps of Engineers have joined together on a study to identify and implement strategies for restoring and protecting the Green/Duwamish River System and its tributaries (Green/Duwamish Ecosystem Restoration Study, 2003). As part of the Green-Duwamish Watershed Water Quality Assessment Program, King County contracted with Portland State University to develop a hydrodynamic and water quality model for the Lower and Middle Green River. This model will be used in Total Maximum Daily Load (TMDL) development, in assessing current water quality conditions in the river, and as a planning tool for evaluating the impacts of future development in the basin. Title: Green River CE-QUAL-W2 Project: A Hydrodynamic and Water Quality Study of the Green River King County, Washington Author: Kraft, Tim, Annear, Robert Leslie, Berger, Chris, Wells, Scott A. Year: 2004 This report describes the data processing and model calibration performed for a hydrodynamic and water quality model of the Green River, located in King County, Washington. Figure 1 shows the location of the river, and the limits of the section of river that was modeled. The Green River flows from its headwaters in the Cascade Mountain foothills through the King County, Washington communities of Auburn, Kent, and Tukwila before discharging into the Duwamish River. Two sections of the river were modeled in this project. The Middle Green River begins in the Cascade Mountain foothills east of Tacoma, and continues downstream to the city of Auburn, WA. The Lower Green River continues from Auburn to the confluence with the Duwamish River, in the town of Tukwila. The Green/Duwamish River system is unique in that it flows through a heavily urbanized and industrialized environment yet supports a large salmon population (Green/Duwamish Ecosystem Restoration Study, 2003). To protect the river and its prime salmon habitat, King County and the US Army Corps of Engineers have joined together on a study to identify and implement strategies for restoring and protecting the Green/Duwamish River System and its tributaries (Green/Duwamish Ecosystem Restoration Study, 2003). As part of the Green-Duwamish Watershed Water Quality Assessment Program, King County contracted with Portland State University to develop a hydrodynamic and water quality model for the Lower and Middle Green River. This model will be used in Total Maximum Daily Load (TMDL) development, in assessing current water quality conditions in the river, and as a planning tool for evaluating the impacts of future development in the basin. Close

• 19. [Article] TMDLS: Statistical Correlations or Mechanistic Modeling?

  In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant ...

  Citation × Citation Citation Abstract Copy Title: TMDLS: Statistical Correlations or Mechanistic Modeling? Author: Wells, Scott A., Cole, Thomas M. Year: 2002 In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach and a mechanistic modeling approach. The system included the Lower Snake River, Brownlee Reservoir, Oxbow Reservoir, and Hells Canyon Reservoir with the focus was on Brownlee Reservoir. The statistical approach used on Brownlee Reservoir divided the system into riverine and lacustrine zones. Field data were then averaged over season and location to provide statistical correlations, such as between total phosphorus (TP) and chlorophyll a (chl a), between an anoxic factor (AF) and TP, and between a hypoxic factor (HP) and TP. The anoxic factor is defined as the number of days when dissolved oxygen was less than 2 mg/l and the hypoxic factor was defined as the number of days when dissolved oxygen was less than 6.5 mg/l. The mechanistic approach used a two-dimensional, unsteady, hydrodynamic and water quality model called CE-QUAL-W2. The model was calibrated to field data over a three year period for 1992 (a low flow year), 1995 (an average flow year), and 1997 (a high flow year). Some of the important questions that the TMDL process was to answer included the following. What level of TP is necessary in the river coming into Brownlee Reservoir to reduce the number of days of hypoxia in the reservoir? What are the causes of low-dissolved oxygen in Brownlee Reservoir and what management strategies can be implemented to improve water quality? This paper examines the strengths and weaknesses of answering management questions using these two approaches. Recommendations are suggested for answering assimilative capacity questions that arise in TMDL studies. Title: TMDLS: Statistical Correlations or Mechanistic Modeling? Author: Wells, Scott A., Cole, Thomas M. Year: 2002 In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach and a mechanistic modeling approach. The system included the Lower Snake River, Brownlee Reservoir, Oxbow Reservoir, and Hells Canyon Reservoir with the focus was on Brownlee Reservoir. The statistical approach used on Brownlee Reservoir divided the system into riverine and lacustrine zones. Field data were then averaged over season and location to provide statistical correlations, such as between total phosphorus (TP) and chlorophyll a (chl a), between an anoxic factor (AF) and TP, and between a hypoxic factor (HP) and TP. The anoxic factor is defined as the number of days when dissolved oxygen was less than 2 mg/l and the hypoxic factor was defined as the number of days when dissolved oxygen was less than 6.5 mg/l. The mechanistic approach used a two-dimensional, unsteady, hydrodynamic and water quality model called CE-QUAL-W2. The model was calibrated to field data over a three year period for 1992 (a low flow year), 1995 (an average flow year), and 1997 (a high flow year). Some of the important questions that the TMDL process was to answer included the following. What level of TP is necessary in the river coming into Brownlee Reservoir to reduce the number of days of hypoxia in the reservoir? What are the causes of low-dissolved oxygen in Brownlee Reservoir and what management strategies can be implemented to improve water quality? This paper examines the strengths and weaknesses of answering management questions using these two approaches. Recommendations are suggested for answering assimilative capacity questions that arise in TMDL studies. Close

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

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

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