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• 1. [Article] Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon.

  High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, ...

  Citation × Citation Citation Abstract Copy Title: Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon. Author: Al-Abbas, Naowar Year: 2018 High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, and making proper improvements. These measures concern the intersection quality of the progression, capacity, and non-vehicular operations (e.g. pedestrian crossings). In this report, we explored high-resolution data obtained from the intersection of SE Division Street and 122nd Avenue. This intersection had some safety concerns as it is considered one of most dangerous intersections in Portland, Oregon. Thus, the first variable we examined from the data was pedestrian wait time when a cross request is made until pass indication is shown. It was found around 60% of pedestrians who crossed in an east-west direction experienced a delay of 30 seconds or more. Although there was more pedestrian demand from the south to west direction, 70% of these pedestrians received a 30 second delay or longer. Delay values determined from controller data in this report only refer to pedestrians who made a request/call to cross at a particular direction in each cycle. Additionally, an alternate means of calculating actual pedestrian delay was also addressed. The other part of the analysis regarded vehicle operations and signal indications. Green time, cycle length, green-to-cycle ratio, and vehicle count per each cycle were all explored. Furthermore, the quality of the progression of coordinated phases of the through vehicular movement on SE division was quantitatively examined using the proportion of vehicles that had arrived during green indication and Arrival Type (AT), and visually, using the Purdue Coordination Diagram (PCD). The results showed that quality of progression was in good standard. Finally, errors found in the data and the accuracy of the results were also addressed. Title: Exploring High-Resolution Data Obtained from ASC/3 Controller of Intersection SE Division St & SE 122nd Ave, Portland, Oregon. Author: Al-Abbas, Naowar Year: 2018 High-resolution data obtained from ASC/3 controllers can be used to create a variety of performance measures, helping engineers and professionals in monitoring intersection performance, identifying issues, and making proper improvements. These measures concern the intersection quality of the progression, capacity, and non-vehicular operations (e.g. pedestrian crossings). In this report, we explored high-resolution data obtained from the intersection of SE Division Street and 122nd Avenue. This intersection had some safety concerns as it is considered one of most dangerous intersections in Portland, Oregon. Thus, the first variable we examined from the data was pedestrian wait time when a cross request is made until pass indication is shown. It was found around 60% of pedestrians who crossed in an east-west direction experienced a delay of 30 seconds or more. Although there was more pedestrian demand from the south to west direction, 70% of these pedestrians received a 30 second delay or longer. Delay values determined from controller data in this report only refer to pedestrians who made a request/call to cross at a particular direction in each cycle. Additionally, an alternate means of calculating actual pedestrian delay was also addressed. The other part of the analysis regarded vehicle operations and signal indications. Green time, cycle length, green-to-cycle ratio, and vehicle count per each cycle were all explored. Furthermore, the quality of the progression of coordinated phases of the through vehicular movement on SE division was quantitatively examined using the proportion of vehicles that had arrived during green indication and Arrival Type (AT), and visually, using the Purdue Coordination Diagram (PCD). The results showed that quality of progression was in good standard. Finally, errors found in the data and the accuracy of the results were also addressed. Close

• 2. [Article] Trace Metals in Stormwater: Alternative Best Management Practices

  Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate ...

  Citation × Citation Citation Abstract Copy Title: Trace Metals in Stormwater: Alternative Best Management Practices Author: Mora, Jennifer Ibeth Year: 2017 Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate the heavy metal (Cu and Zn) removal efficiency of perlite and EarthliteTM to improve in-situ filtration systems for stormwater catchment basins. Stormwater samples from two field sites in Portland, OR, chosen to represent a high-use commercial site and high-traffic urban road, were characterized to inform experimental design and compare to values found in literature. The Linear, Freundlich, and Langmuir isotherm models were used to describe equilibrium data and determine partitioning coefficients for single metal batch studies. Both the Freundlich and Langmuir models fit most single metal batch systems, while Cu-Perlite, Zn-Perlite, and Zn-EarthliteTM, were best fit by the Langmuir model, R2 = 0.9594; 0.9538; 0.9811, respectively. Competitive adsorption behaviors for Cu and Zn were evaluated using a synthetic stormwater recipe where relative concentrations of Cu and Zn were maintained to be consistent with representative stormwater samples. Perlite showed a decrease in the sorption capacity of Cu and Zn in the presence of competing ions in solution. EarthliteTM showed no difference in the affinity for copper uptake between competitive and non-competitive batch experiments. EarthliteTM affinity for Zn decreased by two orders of magnitude in the competitive batch system. The results from this study will be applied to estimate filter lifetime for traditional and advanced stormwater filter systems. These results will inform experimental design in dynamic flow-through experiments using various filter media thereby improving filter design and implementation of stormwater best management practices. Title: Trace Metals in Stormwater: Alternative Best Management Practices Author: Mora, Jennifer Ibeth Year: 2017 Heavy metals, such as copper (Cu) and zinc (Zn), are considered hazardous in natural waters due to their toxicity and non-biodegradability. The focus of this study is to use batch experiments to investigate the heavy metal (Cu and Zn) removal efficiency of perlite and EarthliteTM to improve in-situ filtration systems for stormwater catchment basins. Stormwater samples from two field sites in Portland, OR, chosen to represent a high-use commercial site and high-traffic urban road, were characterized to inform experimental design and compare to values found in literature. The Linear, Freundlich, and Langmuir isotherm models were used to describe equilibrium data and determine partitioning coefficients for single metal batch studies. Both the Freundlich and Langmuir models fit most single metal batch systems, while Cu-Perlite, Zn-Perlite, and Zn-EarthliteTM, were best fit by the Langmuir model, R2 = 0.9594; 0.9538; 0.9811, respectively. Competitive adsorption behaviors for Cu and Zn were evaluated using a synthetic stormwater recipe where relative concentrations of Cu and Zn were maintained to be consistent with representative stormwater samples. Perlite showed a decrease in the sorption capacity of Cu and Zn in the presence of competing ions in solution. EarthliteTM showed no difference in the affinity for copper uptake between competitive and non-competitive batch experiments. EarthliteTM affinity for Zn decreased by two orders of magnitude in the competitive batch system. The results from this study will be applied to estimate filter lifetime for traditional and advanced stormwater filter systems. These results will inform experimental design in dynamic flow-through experiments using various filter media thereby improving filter design and implementation of stormwater best management practices. Close

• 3. [Article] Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water

  Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view ...

  Citation × Citation Citation Abstract Copy Title: Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water Author: Pankow, James F., Marks, Marguerite Colasurdo, Barsanti, Kelley C., Mahmud, Abdullah, Asher, William E., Li, Jingyi, Ying, Qi, Jathar, Shantanu H., Kleeman, Michael J. Year: 2015 Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view (AV) assumptions that OPM levels are not affected by either: a) the molecular. characteristics of the condensing organic compounds (other than simple volatility); or b) co-condensation of water as driven by non-zero relative humidity (RH) values. The simplifying assumptions have allowed parameterized chamber results for formation of secondary organic aerosol (SOA) (e.g., “two-product” (2p) coefficients) to be incorporated in chemical transport models. However, a return towards a less simplistic (and more computationally demanding) molecular view (MV) is needed that acknowledges that atmospheric OPM is a mixture of organic compounds with differing polarities, water, and in some cases dissolved salts. The higher computational cost of MV modeling results from a need for iterative calculations of the composition-dependent gas/particle partition coefficient values. MV modeling of OPM that considered water uptake (but not dissolved salts) was carried out for the southeast United States for the period August 29 through September 7, 2006. Three model variants were used at three universities: CMAQ-RH-2p (at PSU), UCD/CIT-RH-2p (at UCD), and CMAQ-RH-MCM (at TAMU). With the first two, MV structural characteristics (carbon number and numbers of functional groups) were assigned to each of the 2p products used in CMAQv.4.7.1 such that resulting predicted Kp,i values matched those in CMAQv.4.7.1. When water uptake was allowed, most runs assumed that uptake occurred only into the SOA portion, and imposed immiscibility of SOA with primary organic aerosol (POA). (POA is often viewed as rather non-polar, while SOA is commonly viewed as moderately-to-rather polar. Some runs with UCD/CIT-RH-2p were used to investigate the effects of POA/SOA miscibility.) CMAQ-RH-MCM used MCM to generate oxidation products, and assumed miscibility of SOA and POA. In a ∼500 km wide band from Louisiana through to at least North Carolina, CMAQ-RH-2p and UCD/CIT-RH-2p predicted that water uptake can increase SOA levels by as much as 50 to 100% (from a range of ∼1 to 2 μg m-3 to a range of ∼1 to 4 μg m-3). CMAQ-RH-MCM predicted much lower effects of water uptake on SOA levels (<10% increase). The results from CMAQ-RH-2p and UCD/CIT-RH-2p are considered more reflective of reality. In the Alabama/Georgia hotspot, both CMAQ-RH-2p and UCD/CIT-RH-2p predicted aerosol water levels that are up to nearly half the predicted SOA levels, namely ∼0.5 to 2 μg m-3. Such water levels in SOA will affect particle optical properties, viscosity, gas/particle partitioning times, and rates of hydrolysis and water elimination reactions. Title: Molecular View Modeling of Atmospheric Organic Particulate Matter: Incorporating Molecular Structure and Co-Condensation of Water Author: Pankow, James F., Marks, Marguerite Colasurdo, Barsanti, Kelley C., Mahmud, Abdullah, Asher, William E., Li, Jingyi, Ying, Qi, Jathar, Shantanu H., Kleeman, Michael J. Year: 2015 Most urban and regional models used to predict levels of organic particulate matter (OPM) are based on fundamental equations for gas/particle partitioning, but make the highly simplifying, anonymized-view (AV) assumptions that OPM levels are not affected by either: a) the molecular. characteristics of the condensing organic compounds (other than simple volatility); or b) co-condensation of water as driven by non-zero relative humidity (RH) values. The simplifying assumptions have allowed parameterized chamber results for formation of secondary organic aerosol (SOA) (e.g., “two-product” (2p) coefficients) to be incorporated in chemical transport models. However, a return towards a less simplistic (and more computationally demanding) molecular view (MV) is needed that acknowledges that atmospheric OPM is a mixture of organic compounds with differing polarities, water, and in some cases dissolved salts. The higher computational cost of MV modeling results from a need for iterative calculations of the composition-dependent gas/particle partition coefficient values. MV modeling of OPM that considered water uptake (but not dissolved salts) was carried out for the southeast United States for the period August 29 through September 7, 2006. Three model variants were used at three universities: CMAQ-RH-2p (at PSU), UCD/CIT-RH-2p (at UCD), and CMAQ-RH-MCM (at TAMU). With the first two, MV structural characteristics (carbon number and numbers of functional groups) were assigned to each of the 2p products used in CMAQv.4.7.1 such that resulting predicted Kp,i values matched those in CMAQv.4.7.1. When water uptake was allowed, most runs assumed that uptake occurred only into the SOA portion, and imposed immiscibility of SOA with primary organic aerosol (POA). (POA is often viewed as rather non-polar, while SOA is commonly viewed as moderately-to-rather polar. Some runs with UCD/CIT-RH-2p were used to investigate the effects of POA/SOA miscibility.) CMAQ-RH-MCM used MCM to generate oxidation products, and assumed miscibility of SOA and POA. In a ∼500 km wide band from Louisiana through to at least North Carolina, CMAQ-RH-2p and UCD/CIT-RH-2p predicted that water uptake can increase SOA levels by as much as 50 to 100% (from a range of ∼1 to 2 μg m-3 to a range of ∼1 to 4 μg m-3). CMAQ-RH-MCM predicted much lower effects of water uptake on SOA levels (<10% increase). The results from CMAQ-RH-2p and UCD/CIT-RH-2p are considered more reflective of reality. In the Alabama/Georgia hotspot, both CMAQ-RH-2p and UCD/CIT-RH-2p predicted aerosol water levels that are up to nearly half the predicted SOA levels, namely ∼0.5 to 2 μg m-3. Such water levels in SOA will affect particle optical properties, viscosity, gas/particle partitioning times, and rates of hydrolysis and water elimination reactions. Close

• 4. [Article] Acid-Base Equilibria in Organic-Solvent/Water Mixtures and Their Relevance to Gas/Particle Partitioning in the Atmosphere and in Tobacco Smoke

  Acid-base equilibria in organic particulate matter (PM) are poorly understood, but have important implications for air quality and public health. First, acid-base reactions in organic particulate matter ...

  Citation × Citation Citation Abstract Copy Title: Acid-Base Equilibria in Organic-Solvent/Water Mixtures and Their Relevance to Gas/Particle Partitioning in the Atmosphere and in Tobacco Smoke Author: DeGagne, Julia Lynn Year: 2016 Acid-base equilibria in organic particulate matter (PM) are poorly understood, but have important implications for air quality and public health. First, acid-base reactions in organic particulate matter affect the gas/particle partitioning of organic compounds in the atmosphere, and these processes are not currently represented in atmospheric and climate change models. Second, the acid-base balance of tobacco smoke affects the amount of nicotine absorbed by the smoker, and a greater understanding of this balance would help to relate cigarette smoke composition to the addictive properties of cigarettes. This work presents data related to both air quality and tobacco smoke modeling. The gas/particle partitioning behavior of organic acids and bases is highly dependent on acid-base equilibria and speciation between neutral and ionic forms, because ionic compounds do not volatilize. Descriptions of acid dissociation behavior in atmospheric PM have, to date, focused primarily on phases in which the solvent is water; however, atmospheric PM may include up to 90% organic matter. Data is presented here describing the acid dissociation behavior of organic acids and protonated amines in organic/aqueous mixtures (chosen to approximate the characteristics of organic PM) with varying levels of water content. In such mixtures, the preferential solvation of ions and neutral molecules (by the aqueous portion or the organic portion, respectively) affects the acid-base equilibria of the solutes. It is demonstrated that neutralization reactions between acids and bases that create ions are likely to have non-negligible effects on gas/particle partitioning under certain atmospheric conditions. Thus, including acid-base reactions in organic gas/particle partitioning models could result in a greater proportion of acidic and basic compounds partitioning to the particulate phase. In addition, the acid dissociation constants (pKa values) of atmospherically-relevant acids and bases vary with water content. Specifically, as water content increases, the pKa values of organic acids decrease dramatically, while the pKa values of protonated amines changes only slightly. This situation can result in drastically different speciations and partitioning behavior depending on water content. This second part of this work reports some of the data needed to develop an acid-base balance for tobacco smoke PM using electroneutrality as a governing principle. Five brands of cigarettes were sampled and the smoke PM extracted. Cations (sodium, potassium, and ammonia) and anions (organic acids, nitrate, nitrite, and chloride) were measured using ion chromatography. Ammonia and organic acids were also re-measured after the acidification of the sample in order to determine whether "bound" forms of these compounds exist in cigarette PM. Weak acids were determined by acid-base titration to determine whether or not all of the weak acids (including organic acids) had been accounted for by the ion chromatography. Weak bases were also determined by acid-base titration, and the majority of weak base is expected to be accounted for by total nicotine (to be measured in a separate analysis). In terms of total acidic species and total basic species, two of the five cigarette brands measured were relatively basic, and three were relatively acidic. Between 50% and 89% of the titrated acids were accounted for by the anionic species measured in ion chromatography. Based on samples tested after sample acidification, about half of the potential ammonia in tobacco smoke PM exists in "bound" form. The speciation of weak acids and bases in tobacco smoke PM cannot be determined from this data alone, because the equilibrium constants of acid-base reactions are not understood in complex organic media. The data presented here, when combined with data from free-base and total nicotine analyses, represent a first step toward a predictive model of acid-base behavior in tobacco smoke PM. Title: Acid-Base Equilibria in Organic-Solvent/Water Mixtures and Their Relevance to Gas/Particle Partitioning in the Atmosphere and in Tobacco Smoke Author: DeGagne, Julia Lynn Year: 2016 Acid-base equilibria in organic particulate matter (PM) are poorly understood, but have important implications for air quality and public health. First, acid-base reactions in organic particulate matter affect the gas/particle partitioning of organic compounds in the atmosphere, and these processes are not currently represented in atmospheric and climate change models. Second, the acid-base balance of tobacco smoke affects the amount of nicotine absorbed by the smoker, and a greater understanding of this balance would help to relate cigarette smoke composition to the addictive properties of cigarettes. This work presents data related to both air quality and tobacco smoke modeling. The gas/particle partitioning behavior of organic acids and bases is highly dependent on acid-base equilibria and speciation between neutral and ionic forms, because ionic compounds do not volatilize. Descriptions of acid dissociation behavior in atmospheric PM have, to date, focused primarily on phases in which the solvent is water; however, atmospheric PM may include up to 90% organic matter. Data is presented here describing the acid dissociation behavior of organic acids and protonated amines in organic/aqueous mixtures (chosen to approximate the characteristics of organic PM) with varying levels of water content. In such mixtures, the preferential solvation of ions and neutral molecules (by the aqueous portion or the organic portion, respectively) affects the acid-base equilibria of the solutes. It is demonstrated that neutralization reactions between acids and bases that create ions are likely to have non-negligible effects on gas/particle partitioning under certain atmospheric conditions. Thus, including acid-base reactions in organic gas/particle partitioning models could result in a greater proportion of acidic and basic compounds partitioning to the particulate phase. In addition, the acid dissociation constants (pKa values) of atmospherically-relevant acids and bases vary with water content. Specifically, as water content increases, the pKa values of organic acids decrease dramatically, while the pKa values of protonated amines changes only slightly. This situation can result in drastically different speciations and partitioning behavior depending on water content. This second part of this work reports some of the data needed to develop an acid-base balance for tobacco smoke PM using electroneutrality as a governing principle. Five brands of cigarettes were sampled and the smoke PM extracted. Cations (sodium, potassium, and ammonia) and anions (organic acids, nitrate, nitrite, and chloride) were measured using ion chromatography. Ammonia and organic acids were also re-measured after the acidification of the sample in order to determine whether "bound" forms of these compounds exist in cigarette PM. Weak acids were determined by acid-base titration to determine whether or not all of the weak acids (including organic acids) had been accounted for by the ion chromatography. Weak bases were also determined by acid-base titration, and the majority of weak base is expected to be accounted for by total nicotine (to be measured in a separate analysis). In terms of total acidic species and total basic species, two of the five cigarette brands measured were relatively basic, and three were relatively acidic. Between 50% and 89% of the titrated acids were accounted for by the anionic species measured in ion chromatography. Based on samples tested after sample acidification, about half of the potential ammonia in tobacco smoke PM exists in "bound" form. The speciation of weak acids and bases in tobacco smoke PM cannot be determined from this data alone, because the equilibrium constants of acid-base reactions are not understood in complex organic media. The data presented here, when combined with data from free-base and total nicotine analyses, represent a first step toward a predictive model of acid-base behavior in tobacco smoke PM. Close

• 5. [Article] Performance Implications of Bicycle Specific Treatments at Signalized Intersections

  A rise in cycling nationwide has brought an increased awareness of bicycle specific safety concerns, particularly right-hook crashes at signalized intersections. There are several common and emerging signal ...

  Citation × Citation Citation Abstract Copy Title: Performance Implications of Bicycle Specific Treatments at Signalized Intersections Author: Kading, Andrew Year: 2016 A rise in cycling nationwide has brought an increased awareness of bicycle specific safety concerns, particularly right-hook crashes at signalized intersections. There are several common and emerging signal timing strategies that are can be used to improve the safety and efficiency of traffic signals for people on bicycles, including the Leading Bicycle Intervals (LBI), Split LBI, and Exclusive Bicycle Phasing (EBP). The leading and split bicycle intervals provide a head start for bicycles in advance of concurrent and conflicting motor vehicle movements, typically about 3-5 seconds. The EBP provides an interval only when bicycles are moving. To examine the performance and efficiency metrics under a range of bicycle and motor vehicle volumes, a Vissim microsimulation model was developed. Passenger cars, large trucks, bicycles, and pedestrians were modeled to understand the performance across and between the modes. User delay values were extracted from the model and compared to the base case. A total of 210 simulation runs were conducted, accounting for approximately 262.5 hours of simulation. Results indicate a small vehicle delay increase of between 4% - 11% [as delay in seconds per user] for the Split LBI, with thru traffic (which is unaffected by the Split LBI treatment) virtually unaffected at 1% - 2% delay increases; the LBI saw larger increases in vehicle delay from 11% - 19%; and large vehicle delay increases for the EBP (up to 26% for the eastbound approach), but also found an apparent bias in the coordination scheme that led to decreases for the westbound approach. Bicycle delay results showed more variation with the LBI treatment showing little impact, with results ranging from -5% - 5% changes in bicycle delay. Split LBI showed delay increases of 3% - 11% for the thru cyclists, but mixed results for the right turning cyclists, which showed delay results increasing as a function of bicycle traffic. Bicycle delay results for the EBP showed large increases from 100% - 565%. Pedestrians and left turning vehicles were all but unaffected by either the LBI or Split LBI. While the EBP did show changes in delay as high as 22% for pedestrians. This research demonstrates that bicycle specific treatments do impact user delay at busy arterial intersections, although the magnitude of impact differs depending on the treatment used. The use of the Split LBI had little overall impact, suggesting it is an effective treatment if the intersection configuration is correct. The LBI had greater impact, and should be considered for intersections with the correct configuration. The EBP had large delay increases suggesting limited use, only when bicycle volumes are high enough to justify the delay. Title: Performance Implications of Bicycle Specific Treatments at Signalized Intersections Author: Kading, Andrew Year: 2016 A rise in cycling nationwide has brought an increased awareness of bicycle specific safety concerns, particularly right-hook crashes at signalized intersections. There are several common and emerging signal timing strategies that are can be used to improve the safety and efficiency of traffic signals for people on bicycles, including the Leading Bicycle Intervals (LBI), Split LBI, and Exclusive Bicycle Phasing (EBP). The leading and split bicycle intervals provide a head start for bicycles in advance of concurrent and conflicting motor vehicle movements, typically about 3-5 seconds. The EBP provides an interval only when bicycles are moving. To examine the performance and efficiency metrics under a range of bicycle and motor vehicle volumes, a Vissim microsimulation model was developed. Passenger cars, large trucks, bicycles, and pedestrians were modeled to understand the performance across and between the modes. User delay values were extracted from the model and compared to the base case. A total of 210 simulation runs were conducted, accounting for approximately 262.5 hours of simulation. Results indicate a small vehicle delay increase of between 4% - 11% [as delay in seconds per user] for the Split LBI, with thru traffic (which is unaffected by the Split LBI treatment) virtually unaffected at 1% - 2% delay increases; the LBI saw larger increases in vehicle delay from 11% - 19%; and large vehicle delay increases for the EBP (up to 26% for the eastbound approach), but also found an apparent bias in the coordination scheme that led to decreases for the westbound approach. Bicycle delay results showed more variation with the LBI treatment showing little impact, with results ranging from -5% - 5% changes in bicycle delay. Split LBI showed delay increases of 3% - 11% for the thru cyclists, but mixed results for the right turning cyclists, which showed delay results increasing as a function of bicycle traffic. Bicycle delay results for the EBP showed large increases from 100% - 565%. Pedestrians and left turning vehicles were all but unaffected by either the LBI or Split LBI. While the EBP did show changes in delay as high as 22% for pedestrians. This research demonstrates that bicycle specific treatments do impact user delay at busy arterial intersections, although the magnitude of impact differs depending on the treatment used. The use of the Split LBI had little overall impact, suggesting it is an effective treatment if the intersection configuration is correct. The LBI had greater impact, and should be considered for intersections with the correct configuration. The EBP had large delay increases suggesting limited use, only when bicycle volumes are high enough to justify the delay. Close

• 6. [Article] Application of Numerical Modeling to Study River Dynamics: Hydro-Geomorphological Evolution Due to Extreme Events in the Sandy River, Oregon

  The Sandy River (OR) is a costal tributary of the Columbia River and has a steep hydroshed 1316 square kilometers which is located on the western side of Mount Hood (elevation range 3 m to 1800 m). The ...

  Citation × Citation Citation Abstract Copy Title: Application of Numerical Modeling to Study River Dynamics: Hydro-Geomorphological Evolution Due to Extreme Events in the Sandy River, Oregon Author: Muhammad, Sarkawt Hamarahim Year: 2017 The Sandy River (OR) is a costal tributary of the Columbia River and has a steep hydroshed 1316 square kilometers which is located on the western side of Mount Hood (elevation range 3 m to 1800 m). The system exhibits highly variable flow: Its average discharge is ~40 m3/s, and the highest recorded discharge was 1739 m3/s in 1964. In this study I model the geomorphic sensitivity of an 1800m reach located the downstream of the former Marmot Dam, which was removed in 2007. The hydro-geomorphic response to major flood has implications for system management and aquatic life. Studying hydro-geomorphic change requires a systematic approach. Here, I define flows and flood hydrographs for specified return interval based on the observed hydrologic record, and then examine potential hydro-geomorphic changes using a numerical model. A Pearson Type III distribution is used to calculate 100, 75, 50, 25, 10, and 2 year return periods. Extreme event hydrographs are derived by fitting derived and observed flood hydrographs to the gamma distribution curve. Sediment transport and geomorphology are then modeled numerically with Nays2DH, a solver that is part of iRIC software. Because the model is computationally intensive, I model the domain with five different spatial grid resolutions, to find proper grid resolution. The grid resolutions used are 1.5 m, 2 m, 3 m, 4 m, and 5 m. We choose 4 m as optimum grid resolution, based on the convergence of model results. The model is run for extreme event hydrographs with six above return periods. For result visualization and analysis, we focus on flow properties and bed elevation at peak flow and at the end of each event. For both times for each event, important flow and sediment transport parameters are visualized for the entire domain in plane form and eight cross-sections at 200 m intervals. Finally, we divide the geomorphic response into areas of erosion and deposition. Linear regression analyses of mean values of erosion and deposition at peak flow for all extreme events yield R2 of 0.981 for erosion and 0.986 for deposition. The mean erosion and deposition depth at the end of the events is modeled by nonlinear regression with correlation coefficient of 0.965 for erosion and 0.998 for deposition. The regression models provide direct understanding of impacts of different floods on the geomorphic response of the river domain. examination of the model as a whole suggest that the amount of erosion and deposition in the bed and banks is a function of channel geometry, bank and bed geology, riparian area condition and strongly depend on the amount of flow through the channel. Title: Application of Numerical Modeling to Study River Dynamics: Hydro-Geomorphological Evolution Due to Extreme Events in the Sandy River, Oregon Author: Muhammad, Sarkawt Hamarahim Year: 2017 The Sandy River (OR) is a costal tributary of the Columbia River and has a steep hydroshed 1316 square kilometers which is located on the western side of Mount Hood (elevation range 3 m to 1800 m). The system exhibits highly variable flow: Its average discharge is ~40 m3/s, and the highest recorded discharge was 1739 m3/s in 1964. In this study I model the geomorphic sensitivity of an 1800m reach located the downstream of the former Marmot Dam, which was removed in 2007. The hydro-geomorphic response to major flood has implications for system management and aquatic life. Studying hydro-geomorphic change requires a systematic approach. Here, I define flows and flood hydrographs for specified return interval based on the observed hydrologic record, and then examine potential hydro-geomorphic changes using a numerical model. A Pearson Type III distribution is used to calculate 100, 75, 50, 25, 10, and 2 year return periods. Extreme event hydrographs are derived by fitting derived and observed flood hydrographs to the gamma distribution curve. Sediment transport and geomorphology are then modeled numerically with Nays2DH, a solver that is part of iRIC software. Because the model is computationally intensive, I model the domain with five different spatial grid resolutions, to find proper grid resolution. The grid resolutions used are 1.5 m, 2 m, 3 m, 4 m, and 5 m. We choose 4 m as optimum grid resolution, based on the convergence of model results. The model is run for extreme event hydrographs with six above return periods. For result visualization and analysis, we focus on flow properties and bed elevation at peak flow and at the end of each event. For both times for each event, important flow and sediment transport parameters are visualized for the entire domain in plane form and eight cross-sections at 200 m intervals. Finally, we divide the geomorphic response into areas of erosion and deposition. Linear regression analyses of mean values of erosion and deposition at peak flow for all extreme events yield R2 of 0.981 for erosion and 0.986 for deposition. The mean erosion and deposition depth at the end of the events is modeled by nonlinear regression with correlation coefficient of 0.965 for erosion and 0.998 for deposition. The regression models provide direct understanding of impacts of different floods on the geomorphic response of the river domain. examination of the model as a whole suggest that the amount of erosion and deposition in the bed and banks is a function of channel geometry, bank and bed geology, riparian area condition and strongly depend on the amount of flow through the channel. Close