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• 11. [Article] Lower Willamette River Model: Model Calibration

  Water Environment Services of Clackamas County is in the process of planning upgrades on several of its wastewater treatment plants (WWTPs) which discharge into the Lower Willamette River. The goals of ...

  Citation × Citation Citation Abstract Copy Title: Lower Willamette River Model: Model Calibration Author: Berger, Chris, Annear, Robert Leslie, Wells, Scott A. Year: 2001 Water Environment Services of Clackamas County is in the process of planning upgrades on several of its wastewater treatment plants (WWTPs) which discharge into the Lower Willamette River. The goals of the modeling effort were to: • Gather data to construct a computer simulation model of the Lower Willamette River system in order to evaluate the impact of the WWTP discharges on water quality • Ensure that the model accurately represents the system physics and chemistry (flow, temperature, dissolved oxygen and nutrient dynamics) by model calibration • Use the model to evaluate how to meet various future discharge scenarios for Water Environment Services of Clackamas County. This report evaluates the model calibration and discusses issues relative to that calibration effort. The calibration effort focused on model predictions of hydrodynamics (flow and water level), temperature, and eutrophication model parameters (such as nutrients, algae, dissolved oxygen, organic matter, coliform). Title: Lower Willamette River Model: Model Calibration Author: Berger, Chris, Annear, Robert Leslie, Wells, Scott A. Year: 2001 Water Environment Services of Clackamas County is in the process of planning upgrades on several of its wastewater treatment plants (WWTPs) which discharge into the Lower Willamette River. The goals of the modeling effort were to: • Gather data to construct a computer simulation model of the Lower Willamette River system in order to evaluate the impact of the WWTP discharges on water quality • Ensure that the model accurately represents the system physics and chemistry (flow, temperature, dissolved oxygen and nutrient dynamics) by model calibration • Use the model to evaluate how to meet various future discharge scenarios for Water Environment Services of Clackamas County. This report evaluates the model calibration and discusses issues relative to that calibration effort. The calibration effort focused on model predictions of hydrodynamics (flow and water level), temperature, and eutrophication model parameters (such as nutrients, algae, dissolved oxygen, organic matter, coliform). Close

• 12. [Article] Lower Willamette River Model: Boundary Conditions and Model Setup

  Water Environment Services of Clackamas County is in the process of planning upgrades on several of its sewage treatment plants which discharge into the Lower Willamette River. The goals of the modeling ...

  Citation × Citation Citation Abstract Copy Title: Lower Willamette River Model: Boundary Conditions and Model Setup Author: Rodriguez, Herman G., Annear, Robert Leslie, Wells, Scott A., Berger, Chris Year: 2001 Water Environment Services of Clackamas County is in the process of planning upgrades on several of its sewage treatment plants which discharge into the Lower Willamette River. The goals of the modeling effort are to: • Gather data to construct a computer simulation model of the Lower Willamette River system including part of the Lower Columbia River and the Willamette River above the Oregon City Falls; Because of the tidal influence in the Lower Willamette River, portions of the Columbia River that might affect the Lower Willamette River water quality were also modeled. Also, a section of the Willamette River above the head of tide, the Oregon City Falls, was modeled because of the lack of good boundary condition data at the Falls. • Ensure that the model accurately represents the system physics and chemistry (flow, temperature, dissolved oxygen and nutrient dynamics); • Use the model to evaluate how to meet various future discharge scenarios for the sewage district. A hydrodynamic and water quality model, CE-QUAL-W2 Version 3 (Wells, 1997), is being applied to model the Willamette-Columbia system. CE-QUAL-W2 is a two dimensional (longitudinal-vertical), laterally averaged, hydrodynamic and water quality model that has been under development by the Corps of Engineers Waterways Experiments Station (Cole and Wells, 2000). In order to model the system, the following data were required: • Willamette and Columbia River flow, water level and water quality data • Tributary inflows and water quality • Meteorological conditions • Bathymetry of the Columbia and Willamette Rivers and several side channels • Point source inflows and water quality characteristics Many local, state and federal agencies have been collecting data in the Lower Willamette and Columbia Rivers. This report summarizes data used in the modeling effort. Title: Lower Willamette River Model: Boundary Conditions and Model Setup Author: Rodriguez, Herman G., Annear, Robert Leslie, Wells, Scott A., Berger, Chris Year: 2001 Water Environment Services of Clackamas County is in the process of planning upgrades on several of its sewage treatment plants which discharge into the Lower Willamette River. The goals of the modeling effort are to: • Gather data to construct a computer simulation model of the Lower Willamette River system including part of the Lower Columbia River and the Willamette River above the Oregon City Falls; Because of the tidal influence in the Lower Willamette River, portions of the Columbia River that might affect the Lower Willamette River water quality were also modeled. Also, a section of the Willamette River above the head of tide, the Oregon City Falls, was modeled because of the lack of good boundary condition data at the Falls. • Ensure that the model accurately represents the system physics and chemistry (flow, temperature, dissolved oxygen and nutrient dynamics); • Use the model to evaluate how to meet various future discharge scenarios for the sewage district. A hydrodynamic and water quality model, CE-QUAL-W2 Version 3 (Wells, 1997), is being applied to model the Willamette-Columbia system. CE-QUAL-W2 is a two dimensional (longitudinal-vertical), laterally averaged, hydrodynamic and water quality model that has been under development by the Corps of Engineers Waterways Experiments Station (Cole and Wells, 2000). In order to model the system, the following data were required: • Willamette and Columbia River flow, water level and water quality data • Tributary inflows and water quality • Meteorological conditions • Bathymetry of the Columbia and Willamette Rivers and several side channels • Point source inflows and water quality characteristics Many local, state and federal agencies have been collecting data in the Lower Willamette and Columbia Rivers. This report summarizes data used in the modeling effort. Close

• 13. [Article] Modeling Macrophytes of the Columbia Slough, Oregon

  The Columbia Slough is a tidally influenced freshwater system of wetlands, channels, and lakes located within the Portland, Oregon metropolitan area at the confluence of the Willamette and Columbia Rivers. ...

  Citation × Citation Citation Abstract Copy Title: Modeling Macrophytes of the Columbia Slough, Oregon Author: Berger, Chris, Wells, Scott A. Year: 1999 The Columbia Slough is a tidally influenced freshwater system of wetlands, channels, and lakes located within the Portland, Oregon metropolitan area at the confluence of the Willamette and Columbia Rivers. It is a eutrophic water body susceptible to algae blooms and crashes and periods of high pH which violate water quality standards. High nutrient loads from groundwater principally controls algae productivity. Past structural changes to the Columbia Slough have included filling of wetlands and lakes and the construction of levees, dikes, culverts and irrigation channels. These changes have altered the natural flow dynamics creating an environment more conducive to eutrophication. A hydrodynamic and water quality model was used to evaluate management alternatives to improve water quality in the system. The model was developed using the Corps of Engineers two-dimensional, laterally averaged, dynamic water quality model, CE-QUAL-W2. CE-QUAL-W2 consists of directly coupled hydrodynamic and water quality transport. Recently, a management strategy of flow augmentation using groundwater coupled with shorter in-pool detention times has reduced algae growth. However, the resulting increase in water clarity has created an environment favorable to the growth of aquatic plants. The aquatic plants, or macrophytes, have increased water levels and detention time by increasing channel friction and blockage. Accurate predictions of hydrodynamics were essential for evaluating the water quality impact of flow management strategies. Macrophytes and epiphyton affect nutrient cycling by removing nutrients from the water column and sediment. To help evaluate the study of new management alternatives, the Columbia Slough model was expanded to simulate the water quality and hydrodynamic effects of macrophytes and epiphyton. Title: Modeling Macrophytes of the Columbia Slough, Oregon Author: Berger, Chris, Wells, Scott A. Year: 1999 The Columbia Slough is a tidally influenced freshwater system of wetlands, channels, and lakes located within the Portland, Oregon metropolitan area at the confluence of the Willamette and Columbia Rivers. It is a eutrophic water body susceptible to algae blooms and crashes and periods of high pH which violate water quality standards. High nutrient loads from groundwater principally controls algae productivity. Past structural changes to the Columbia Slough have included filling of wetlands and lakes and the construction of levees, dikes, culverts and irrigation channels. These changes have altered the natural flow dynamics creating an environment more conducive to eutrophication. A hydrodynamic and water quality model was used to evaluate management alternatives to improve water quality in the system. The model was developed using the Corps of Engineers two-dimensional, laterally averaged, dynamic water quality model, CE-QUAL-W2. CE-QUAL-W2 consists of directly coupled hydrodynamic and water quality transport. Recently, a management strategy of flow augmentation using groundwater coupled with shorter in-pool detention times has reduced algae growth. However, the resulting increase in water clarity has created an environment favorable to the growth of aquatic plants. The aquatic plants, or macrophytes, have increased water levels and detention time by increasing channel friction and blockage. Accurate predictions of hydrodynamics were essential for evaluating the water quality impact of flow management strategies. Macrophytes and epiphyton affect nutrient cycling by removing nutrients from the water column and sediment. To help evaluate the study of new management alternatives, the Columbia Slough model was expanded to simulate the water quality and hydrodynamic effects of macrophytes and epiphyton. Close

• 14. [Article] Upper Spokane River Model in Idaho: Boundary Conditions and Model Setup for 2001

  The Spokane River in Idaho originates in Coeur d’Alene Lake (Figure 1 and Figure 2). The section of the Spokane River from Coeur d’Alene Lake to the Washington state line is the subject of a water quality ...

  Citation × Citation Citation Abstract Copy Title: Upper Spokane River Model in Idaho: Boundary Conditions and Model Setup for 2001 Author: Wells, Scott A., Annear, Robert Leslie, Berger, Chris Year: 2003 The Spokane River in Idaho originates in Coeur d’Alene Lake (Figure 1 and Figure 2). The section of the Spokane River from Coeur d’Alene Lake to the Washington state line is the subject of a water quality study for the US Environmental Protection Agency. The objective of this study is to create a water quality and hydrodynamic model of the Spokane River in Idaho using CE-QUAL-W2 Version 3.1 (Cole and Wells, 2002). Since the Spokane River is water quality limited, a hydrodynamic and water quality model for the Spokane River in Washington was developed by Portland State University for the Corps of Engineers and the Washington Department of Ecology from the Idaho border to the outlet of Long Lake. An earlier study of the Spokane River was undertaken by Limno-Tech (2001a, 2001b) for the domain shown in Figure 3. Limno-Tech used an earlier version of CE-QUAL-W2, Version 2, for the Reservoir portion of the Spokane River from Post Falls Dam to Coeur d’Alene Lake and a steady-state EPA model, QUAL2E, for the riverine section from Post Falls Dam to the Idaho-Washington border. The steady-state QUAL2E model was not adequate to deal with flow and water quality dynamics. Hence, the riverine portion of the model and the reservoir portion were both upgraded to CE-QUAL-W2 Version 3.1. Because of the necessity of looking at the entire water basin, a model using CE-QUAL-W2 Version 3.1 of the Idaho portion of the Spokane River model was developed to assess water quality management strategies for the Idaho side of the Spokane River. Title: Upper Spokane River Model in Idaho: Boundary Conditions and Model Setup for 2001 Author: Wells, Scott A., Annear, Robert Leslie, Berger, Chris Year: 2003 The Spokane River in Idaho originates in Coeur d’Alene Lake (Figure 1 and Figure 2). The section of the Spokane River from Coeur d’Alene Lake to the Washington state line is the subject of a water quality study for the US Environmental Protection Agency. The objective of this study is to create a water quality and hydrodynamic model of the Spokane River in Idaho using CE-QUAL-W2 Version 3.1 (Cole and Wells, 2002). Since the Spokane River is water quality limited, a hydrodynamic and water quality model for the Spokane River in Washington was developed by Portland State University for the Corps of Engineers and the Washington Department of Ecology from the Idaho border to the outlet of Long Lake. An earlier study of the Spokane River was undertaken by Limno-Tech (2001a, 2001b) for the domain shown in Figure 3. Limno-Tech used an earlier version of CE-QUAL-W2, Version 2, for the Reservoir portion of the Spokane River from Post Falls Dam to Coeur d’Alene Lake and a steady-state EPA model, QUAL2E, for the riverine section from Post Falls Dam to the Idaho-Washington border. The steady-state QUAL2E model was not adequate to deal with flow and water quality dynamics. Hence, the riverine portion of the model and the reservoir portion were both upgraded to CE-QUAL-W2 Version 3.1. Because of the necessity of looking at the entire water basin, a model using CE-QUAL-W2 Version 3.1 of the Idaho portion of the Spokane River model was developed to assess water quality management strategies for the Idaho side of the Spokane River. Close

• 15. [Article] Modeling of Historic Columbia River Flood Impacts Based on Delft 3D Simulations

  Natural and anthropogenic processes over the past 150 years have altered the bathymetry of the Lower Columbia River (LCR) and have changed the long wave propagation of tides and floods. Possible causes ...

  Citation × Citation Citation Abstract Copy Title: Modeling of Historic Columbia River Flood Impacts Based on Delft 3D Simulations Author: Helaire, Lumas Terence Year: 2016 Natural and anthropogenic processes over the past 150 years have altered the bathymetry of the Lower Columbia River (LCR) and have changed the long wave propagation of tides and floods. Possible causes for the increase in tidal amplitudes (+7% in tidal range in Astoria) are decreases in river discharge, lengthening of the river channel due to the construction of jetties at the mouth, dredging and deepening of the shipping channel, and reduction of the tidal prism due to the filling and diking of tidal wetlands. In this study, changes in the characteristics of long waves are elucidated by developing two hydrodynamic models of the LCR which reflect historical and modern bathymetric conditions and forcing. The historic model simulates late 19th century conditions and is extensively validated using recently recovered tide records along the LCR (e.g., Astoria, 1853-1876) and river stage measurements (e.g., Portland, 1876-1964). Results suggest that water levels in Portland at low river discharge are up to 0.5-1.0m lower than in the past. However, historical water levels during a flood scenario based on the 1880 spring freshet are similar to modern water levels. Since tidal range in the modern scenario is persistently higher at all locations, the flood risk in many locations along the LCR has increased for the same boundary conditions. The results are explained by considering the governing equations of momentum and mass-conservation. At low river flow, greater depth leads to reduced frictional effects, producing amplified tidal range and tidal velocities but a decreased river slope (and lower Portland water levels). At high flow, the modern flood is confined by dikes and the loss of wetlands, which counteracts the effect of decreased friction. Nonetheless, the high friction of the historical wooded floodplain also confined the historical flood path. Hence, historical and modern flood heights are surprisingly similar, though scaling analysis suggests that the historical flood wave was more diffusive. Title: Modeling of Historic Columbia River Flood Impacts Based on Delft 3D Simulations Author: Helaire, Lumas Terence Year: 2016 Natural and anthropogenic processes over the past 150 years have altered the bathymetry of the Lower Columbia River (LCR) and have changed the long wave propagation of tides and floods. Possible causes for the increase in tidal amplitudes (+7% in tidal range in Astoria) are decreases in river discharge, lengthening of the river channel due to the construction of jetties at the mouth, dredging and deepening of the shipping channel, and reduction of the tidal prism due to the filling and diking of tidal wetlands. In this study, changes in the characteristics of long waves are elucidated by developing two hydrodynamic models of the LCR which reflect historical and modern bathymetric conditions and forcing. The historic model simulates late 19th century conditions and is extensively validated using recently recovered tide records along the LCR (e.g., Astoria, 1853-1876) and river stage measurements (e.g., Portland, 1876-1964). Results suggest that water levels in Portland at low river discharge are up to 0.5-1.0m lower than in the past. However, historical water levels during a flood scenario based on the 1880 spring freshet are similar to modern water levels. Since tidal range in the modern scenario is persistently higher at all locations, the flood risk in many locations along the LCR has increased for the same boundary conditions. The results are explained by considering the governing equations of momentum and mass-conservation. At low river flow, greater depth leads to reduced frictional effects, producing amplified tidal range and tidal velocities but a decreased river slope (and lower Portland water levels). At high flow, the modern flood is confined by dikes and the loss of wetlands, which counteracts the effect of decreased friction. Nonetheless, the high friction of the historical wooded floodplain also confined the historical flood path. Hence, historical and modern flood heights are surprisingly similar, though scaling analysis suggests that the historical flood wave was more diffusive. Close

• 16. [Article] Upper Spokane River Model: Model Calibration, 2001

  The Upper Spokane River system under consideration is located in the Northeastern part of Washington State and runs from the Stateline with Idaho, River mile (RM) 96.0, downstream to Long Lake dam at RM ...

  Citation × Citation Citation Abstract Copy Title: Upper Spokane River Model: Model Calibration, 2001 Author: Berger, Chris, Annear, Robert Leslie, Welle, Benjamin Year: 2003 The Upper Spokane River system under consideration is located in the Northeastern part of Washington State and runs from the Stateline with Idaho, River mile (RM) 96.0, downstream to Long Lake dam at RM 32.5. Figure 1 shows the river system and an outline the boundaries of the City of Spokane. The Washington Department of Ecology (Ecology) is interested in a water quality model for the Upper Spokane River system for use in developing Total Maximum Daily Loads (TMDLs). As a result, Ecology and the Corps of Engineers funded a study to develop a water quality and hydrodynamic model of the Spokane River system for the years 1991 and 2000. Since the City of Spokane and other point dischargers to the Spokane River have taken considerable field data in the Spokane River system during 2001, the City of Spokane funded this study primarily to: • Continue the development of the Spokane River model for the year 2001, and • Ensure that the model retains its calibration for the year 2001 A hydrodynamic and water quality model, CE-QUAL-W2 Version 3 (Wells, 1997), was applied to the Spokane River system for the years 1991 and 2000. CE-QUAL-W2 is a two dimensional (longitudinalvertical), laterally averaged, hydrodynamic and water quality model that has been under development by the Corps of Engineers Waterways Experiments Station (Cole and Wells, 2000). This report evaluates the 2001 model calibration and discusses issues relative to that calibration effort. The calibration effort focused on model predictions of hydrodynamics (flow and water level), temperature, and eutrophication model parameters (such as nutrients, algae, dissolved oxygen, organic matter, coliform). The model calibration period was from March 15, 2001 to October 31, 2001. Title: Upper Spokane River Model: Model Calibration, 2001 Author: Berger, Chris, Annear, Robert Leslie, Welle, Benjamin Year: 2003 The Upper Spokane River system under consideration is located in the Northeastern part of Washington State and runs from the Stateline with Idaho, River mile (RM) 96.0, downstream to Long Lake dam at RM 32.5. Figure 1 shows the river system and an outline the boundaries of the City of Spokane. The Washington Department of Ecology (Ecology) is interested in a water quality model for the Upper Spokane River system for use in developing Total Maximum Daily Loads (TMDLs). As a result, Ecology and the Corps of Engineers funded a study to develop a water quality and hydrodynamic model of the Spokane River system for the years 1991 and 2000. Since the City of Spokane and other point dischargers to the Spokane River have taken considerable field data in the Spokane River system during 2001, the City of Spokane funded this study primarily to: • Continue the development of the Spokane River model for the year 2001, and • Ensure that the model retains its calibration for the year 2001 A hydrodynamic and water quality model, CE-QUAL-W2 Version 3 (Wells, 1997), was applied to the Spokane River system for the years 1991 and 2000. CE-QUAL-W2 is a two dimensional (longitudinalvertical), laterally averaged, hydrodynamic and water quality model that has been under development by the Corps of Engineers Waterways Experiments Station (Cole and Wells, 2000). This report evaluates the 2001 model calibration and discusses issues relative to that calibration effort. The calibration effort focused on model predictions of hydrodynamics (flow and water level), temperature, and eutrophication model parameters (such as nutrients, algae, dissolved oxygen, organic matter, coliform). The model calibration period was from March 15, 2001 to October 31, 2001. Close

• 17. [Article] Upper Spokane River Model in Idaho: Boundary Conditions and Model Setup and Calibration for 2001 and 2004

  As a result of a Total Maximum Daily Load (TMDL) study of the Spokane River in Washington, a hydrodynamic and water quality model for the Spokane River was developed by Portland State University (PSU) ...

  Citation × Citation Citation Abstract Copy Title: Upper Spokane River Model in Idaho: Boundary Conditions and Model Setup and Calibration for 2001 and 2004 Author: Annear, Robert Leslie, Wells, Scott A., Berger, Chris Year: 2005 As a result of a Total Maximum Daily Load (TMDL) study of the Spokane River in Washington, a hydrodynamic and water quality model for the Spokane River was developed by Portland State University (PSU) for the Corps of Engineers and the Washington Department of Ecology from the Washington-Idaho state line to the outlet of Long Lake. An earlier study of the Spokane River was undertaken by Limno-Tech (2001a, 2001b) for the domain shown in Figure 3. Limno-Tech used an earlier version of CE-QUAL-W2, Version 2, for the Reservoir portion of the Spokane River from Post Falls Dam to Coeur d’Alene Lake and a steady-state EPA model, QUAL2E, for the riverine section from Post Falls Dam to the Idaho-Washington State Line. The steady-state QUAL2E model was not adequate to deal with flow and water quality dynamics. Hence, the riverine portion of the model and the reservoir portion were both upgraded to CE-QUAL-W2 Version 3.1. PSU developed the CE-QUAL-W2 model, but did not have adequate data for model calibration. The set-up of this model was described in the following report: * Wells et al. (2003) - Upper Spokane River Model in Idaho: Boundary Conditions and Model Setup for 2001 Because of the necessity of looking at the entire river basin, a model using CE-QUAL-W2 Version 3.1 of the Idaho portion of the Spokane River model was developed to assess water quality management strategies for the Idaho side of the Spokane River. The objective of this study was to use new field data from 2001 and 2004 to improve the model calibration for the Idaho portion of the Spokane River and reevaluate the work done by Wells et al. (2003). Title: Upper Spokane River Model in Idaho: Boundary Conditions and Model Setup and Calibration for 2001 and 2004 Author: Annear, Robert Leslie, Wells, Scott A., Berger, Chris Year: 2005 As a result of a Total Maximum Daily Load (TMDL) study of the Spokane River in Washington, a hydrodynamic and water quality model for the Spokane River was developed by Portland State University (PSU) for the Corps of Engineers and the Washington Department of Ecology from the Washington-Idaho state line to the outlet of Long Lake. An earlier study of the Spokane River was undertaken by Limno-Tech (2001a, 2001b) for the domain shown in Figure 3. Limno-Tech used an earlier version of CE-QUAL-W2, Version 2, for the Reservoir portion of the Spokane River from Post Falls Dam to Coeur d’Alene Lake and a steady-state EPA model, QUAL2E, for the riverine section from Post Falls Dam to the Idaho-Washington State Line. The steady-state QUAL2E model was not adequate to deal with flow and water quality dynamics. Hence, the riverine portion of the model and the reservoir portion were both upgraded to CE-QUAL-W2 Version 3.1. PSU developed the CE-QUAL-W2 model, but did not have adequate data for model calibration. The set-up of this model was described in the following report: * Wells et al. (2003) - Upper Spokane River Model in Idaho: Boundary Conditions and Model Setup for 2001 Because of the necessity of looking at the entire river basin, a model using CE-QUAL-W2 Version 3.1 of the Idaho portion of the Spokane River model was developed to assess water quality management strategies for the Idaho side of the Spokane River. The objective of this study was to use new field data from 2001 and 2004 to improve the model calibration for the Idaho portion of the Spokane River and reevaluate the work done by Wells et al. (2003). Close

• 18. [Image] Summary Review of Available Models for Groundwater Flow and Contaminant Migration

  	Citation × Citation Citation Abstract Copy Title: Summary Review of Available Models for Groundwater Flow and Contaminant Migration Year: 1993 Title: Summary Review of Available Models for Groundwater Flow and Contaminant Migration Year: 1993 Close

• 19. [Article] A macroscale measurement and modeling approach to improve understanding of the hydrology of steep, forested hillslopes

  The dominant controls on flow generation in steep, forested hillslopes are poorly understood. This dissertation examined the dominant flow processes operating at the hillslope scale, using a combined ...

  Citation × Citation Citation Abstract Copy Title: A macroscale measurement and modeling approach to improve understanding of the hydrology of steep, forested hillslopes Author: Graham, Christopher Brian The dominant controls on flow generation in steep, forested hillslopes are poorly understood. This dissertation examined the dominant flow processes operating at the hillslope scale, using a combined macroscale measurement and model development and analysis framework. Irrigation experiments at two steep forested hillslopes were conducted to isolate individual hillslope flow components and reveal the dominant controls on flow routing to the stream. A new perceptual model of flow processes at the hillslope scale was developed from these field experiments that included three key components: 1) A connected preferential flow network located at the soil/bedrock interface controls lateral water and solute transport, 2) The bedrock surface controls the subsurface flow routing, and 3) Bedrock is permeable, and acts as a sink for precipitation at the hillslope scale. These components formed the basis of a new, low dimensional numerical model that was used to represent, quantitatively, qualitative experimental findings. A multiple criteria calibration using hydrometric and tracer experimental data was conducted to evaluate the model and determine parameter identifiability. The model was able to adequately reproduce both hydrometric response to precipitation, and a tracer application breakthrough. The model was then used within a virtual experiment framework to test the dominant controls on the whole storm precipitation / discharge threshold relationship at the catchment scale. The modeling experiments showed that the macroscale precipitation / discharge threshold was controlled by a balance between antecedent evaporation (evaporation rate times antecedent drainage time), and geologic factors (bedrock permeability and subsurface storage volume). Overall, these findings suggest that making measurements at the scale of the processes one wishes to understand, and constructing numerical models based on the dominant processes at the same scale may be a first step towards the development of macroscale laws of hillslope behavior. Title: A macroscale measurement and modeling approach to improve understanding of the hydrology of steep, forested hillslopes Author: Graham, Christopher Brian The dominant controls on flow generation in steep, forested hillslopes are poorly understood. This dissertation examined the dominant flow processes operating at the hillslope scale, using a combined macroscale measurement and model development and analysis framework. Irrigation experiments at two steep forested hillslopes were conducted to isolate individual hillslope flow components and reveal the dominant controls on flow routing to the stream. A new perceptual model of flow processes at the hillslope scale was developed from these field experiments that included three key components: 1) A connected preferential flow network located at the soil/bedrock interface controls lateral water and solute transport, 2) The bedrock surface controls the subsurface flow routing, and 3) Bedrock is permeable, and acts as a sink for precipitation at the hillslope scale. These components formed the basis of a new, low dimensional numerical model that was used to represent, quantitatively, qualitative experimental findings. A multiple criteria calibration using hydrometric and tracer experimental data was conducted to evaluate the model and determine parameter identifiability. The model was able to adequately reproduce both hydrometric response to precipitation, and a tracer application breakthrough. The model was then used within a virtual experiment framework to test the dominant controls on the whole storm precipitation / discharge threshold relationship at the catchment scale. The modeling experiments showed that the macroscale precipitation / discharge threshold was controlled by a balance between antecedent evaporation (evaporation rate times antecedent drainage time), and geologic factors (bedrock permeability and subsurface storage volume). Overall, these findings suggest that making measurements at the scale of the processes one wishes to understand, and constructing numerical models based on the dominant processes at the same scale may be a first step towards the development of macroscale laws of hillslope behavior. Close

• 20. [Image] Stream Flow Gauging

  	Citation × Citation Citation Abstract Copy Title: Stream Flow Gauging Year: 1997 Title: Stream Flow Gauging Year: 1997 Close