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• 1. [Article] An Assessment of the Impacts of Climate Change on the Upper Clackamas River Basin with a Distributed Hydrologic Model

  The Pacific Northwest is dependent on seasonal snowmelt for water resources that support a significant portion of its economy. Increased temperatures resulting from higher concentrations of atmospheric ...

  Citation × Citation Citation Abstract Copy Title: An Assessment of the Impacts of Climate Change on the Upper Clackamas River Basin with a Distributed Hydrologic Model Author: Graves, David Year: 2005 The Pacific Northwest is dependent on seasonal snowmelt for water resources that support a significant portion of its economy. Increased temperatures resulting from higher concentrations of atmospheric greenhouse gases may cause disruptions to these resources because of reductions in the annual snowpack and variations of the timing of snowmelt. This study reconstructs and applies a GIS-based distributed hydrologic model at a monthly scale to assess the effects of future climate change on runoff from the Upper Clackamas River Basin (located near Portland, Oregon). Historic flow data and snow measurements are used to calibrate and test the perfonnance of the hydro logic model for a contemporary period (1971-2000), and the model is run for two future scenarios (2010-2039 and 2070-2099) using IS92 climate change scenarios from two global climate circulation models (Hadley and Canadian Centre for Climate) as inputs. The results forecast that mean peak snowpack in the study area will drop dramatically (36% to 49% by 2010-2039, and 83% to 88% by 2070-2099), resulting in earlier runoff and diminished spring and summer flows. Increases to mean winter runoff by by the 2070-2099 period vary from moderate (13.7%) to large (46.4%), depending on the changes to precipitation forecasted by the global climate circulation models. These results are similar to those of other studies in areas dependent on snowpack for seasonal runoff, but the reductions to snowpack are more severe in this study than similar studies for the entire Columbia Basin, presumably because the elevations of much of the Upper Clackamas Basin are near the current mid-winter snow line. Title: An Assessment of the Impacts of Climate Change on the Upper Clackamas River Basin with a Distributed Hydrologic Model Author: Graves, David Year: 2005 The Pacific Northwest is dependent on seasonal snowmelt for water resources that support a significant portion of its economy. Increased temperatures resulting from higher concentrations of atmospheric greenhouse gases may cause disruptions to these resources because of reductions in the annual snowpack and variations of the timing of snowmelt. This study reconstructs and applies a GIS-based distributed hydrologic model at a monthly scale to assess the effects of future climate change on runoff from the Upper Clackamas River Basin (located near Portland, Oregon). Historic flow data and snow measurements are used to calibrate and test the perfonnance of the hydro logic model for a contemporary period (1971-2000), and the model is run for two future scenarios (2010-2039 and 2070-2099) using IS92 climate change scenarios from two global climate circulation models (Hadley and Canadian Centre for Climate) as inputs. The results forecast that mean peak snowpack in the study area will drop dramatically (36% to 49% by 2010-2039, and 83% to 88% by 2070-2099), resulting in earlier runoff and diminished spring and summer flows. Increases to mean winter runoff by by the 2070-2099 period vary from moderate (13.7%) to large (46.4%), depending on the changes to precipitation forecasted by the global climate circulation models. These results are similar to those of other studies in areas dependent on snowpack for seasonal runoff, but the reductions to snowpack are more severe in this study than similar studies for the entire Columbia Basin, presumably because the elevations of much of the Upper Clackamas Basin are near the current mid-winter snow line. Close

• 2. [Article] Oxygen Demand Trends, Land Cover Change, and Water Quality Management for an Urbanizing Oregon Watershed

  In-stream aquatic habitat depends on adequate levels of dissolved oxygen. Human alteration of the landscape has an extensive influence on the biogeochemical processes that drive oxygen cycling in streams. ...

  Citation × Citation Citation Abstract Copy Title: Oxygen Demand Trends, Land Cover Change, and Water Quality Management for an Urbanizing Oregon Watershed Author: Boeder, Michael Karl Year: 2006 In-stream aquatic habitat depends on adequate levels of dissolved oxygen. Human alteration of the landscape has an extensive influence on the biogeochemical processes that drive oxygen cycling in streams. Historic datasets allow researchers to track trends in chemical parameters concomitant with urbanization, while land cover change analysis allows researchers to identify linkages between water quality trends and landscape change. Using the Seasonal Kendall's test, I examined water quality trends in oxygen demand variables during the mid-1990s to 2003, for twelve sites in the Rock Creek sub-watershed of the Tualatin River, northwest Oregon. Significant trends occurred in each parameter. Dissolved oxygen (DO (%sat)) increased at five sites. Chemical oxygen demand (COD) decreased at seven sites. Total Kjeldahl nitrogen (TKN) decreased at five sites and increased at one site. Ammonium (NH3-N) decreased at one site and increased at one site. Multiple linear regression indicates that nitrogenous oxygen demand accounts for a significant amount of variance in COD at ten of the twelve sites (adjusted R2values from 0.14 to 0.73). Aerial photo interpretation revealed significant land cover change in agricultural land cover (-8% for the entire basin area) and residential land cover (+10% for the entire basin area). Correlation results between seasonal oxygen demand data and land cover values at multiple scales indicated that: (I) forest cover negatively influences COD at the full sub-basin scale and positively influences NH3-N at local scales, (2) residential land cover positively influences DO (%sat) values at local scales, (3) agricultural land cover does not influence oxygen demand at any land cover assessment scale, ( 4) local topography negatively influences TKN and NH3-N, and (5) urban runoff management infrastructure correlates positively with COD. Study results indicate that, with the exception of forested land, local scale land cover and landscape variables dominate influence on oxygen demand in the Rock Creek basin. Since DO conditions have improved in these streams, watershed management efforts should emphasize local influences in order to continue to maintain stream health. Title: Oxygen Demand Trends, Land Cover Change, and Water Quality Management for an Urbanizing Oregon Watershed Author: Boeder, Michael Karl Year: 2006 In-stream aquatic habitat depends on adequate levels of dissolved oxygen. Human alteration of the landscape has an extensive influence on the biogeochemical processes that drive oxygen cycling in streams. Historic datasets allow researchers to track trends in chemical parameters concomitant with urbanization, while land cover change analysis allows researchers to identify linkages between water quality trends and landscape change. Using the Seasonal Kendall's test, I examined water quality trends in oxygen demand variables during the mid-1990s to 2003, for twelve sites in the Rock Creek sub-watershed of the Tualatin River, northwest Oregon. Significant trends occurred in each parameter. Dissolved oxygen (DO (%sat)) increased at five sites. Chemical oxygen demand (COD) decreased at seven sites. Total Kjeldahl nitrogen (TKN) decreased at five sites and increased at one site. Ammonium (NH3-N) decreased at one site and increased at one site. Multiple linear regression indicates that nitrogenous oxygen demand accounts for a significant amount of variance in COD at ten of the twelve sites (adjusted R2values from 0.14 to 0.73). Aerial photo interpretation revealed significant land cover change in agricultural land cover (-8% for the entire basin area) and residential land cover (+10% for the entire basin area). Correlation results between seasonal oxygen demand data and land cover values at multiple scales indicated that: (I) forest cover negatively influences COD at the full sub-basin scale and positively influences NH3-N at local scales, (2) residential land cover positively influences DO (%sat) values at local scales, (3) agricultural land cover does not influence oxygen demand at any land cover assessment scale, ( 4) local topography negatively influences TKN and NH3-N, and (5) urban runoff management infrastructure correlates positively with COD. Study results indicate that, with the exception of forested land, local scale land cover and landscape variables dominate influence on oxygen demand in the Rock Creek basin. Since DO conditions have improved in these streams, watershed management efforts should emphasize local influences in order to continue to maintain stream health. Close

• 3. [Article] Stream Temperature Management in the Tualatin Watershed: Is it Improving Salmonid Habitat?

  The purpose of this paper is to examine the literature from scientific and governmental entities that describes the problems with elevated stream temperatures in the Tualatin basin, the actions being taken ...

  Citation × Citation Citation Abstract Copy Title: Stream Temperature Management in the Tualatin Watershed: Is it Improving Salmonid Habitat? Author: Hennings, Raymond Banks Year: 2014 The purpose of this paper is to examine the literature from scientific and governmental entities that describes the problems with elevated stream temperatures in the Tualatin basin, the actions being taken to resolve those problems, and to assess whether these actions are meeting the goal of improving salmonid habitat in the basin. Elevated stream temperatures are considered a pollutant under the US Clean Water Act (Clean Water Act 1972, as amended) because increased stream temperatures can be harmful to native aquatic biota, particularly salmonid fish species that have evolved to use cold water (IMST 2004). Title: Stream Temperature Management in the Tualatin Watershed: Is it Improving Salmonid Habitat? Author: Hennings, Raymond Banks Year: 2014 The purpose of this paper is to examine the literature from scientific and governmental entities that describes the problems with elevated stream temperatures in the Tualatin basin, the actions being taken to resolve those problems, and to assess whether these actions are meeting the goal of improving salmonid habitat in the basin. Elevated stream temperatures are considered a pollutant under the US Clean Water Act (Clean Water Act 1972, as amended) because increased stream temperatures can be harmful to native aquatic biota, particularly salmonid fish species that have evolved to use cold water (IMST 2004). Close

• 4. [Article] Impacts of Climate Change and Urban Development on Water Resources in the Tualatin River Basin

  Potential impacts of climate change on the water resources of the Pacific Northwest of the United States include earlier peak runoff, reduced summer flows, and increased winter flooding. An increase in ...

  Citation × Citation Citation Abstract Copy Title: Impacts of Climate Change and Urban Development on Water Resources in the Tualatin River Basin Author: Praskievicz, Sarah Year: 2009 Potential impacts of climate change on the water resources of the Pacific Northwest of the United States include earlier peak runoff, reduced summer flows, and increased winter flooding. An increase in impervious surfaces, accompanied by urban development, is known to decrease infiltration and increase surface runoff. Alterations of flow amount and pathways can alter water quality through dilution or flushing effects. I used the United States Environmental Protection Agency's Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) modeling system to investigate the relative importance of future climate change and land use change in determining the quantity and quality of freshwater resources in north western Oregon's Tualatin River Basin. The basin was chosen for this study because it is rapidly urbanizing and representative of other low-elevation basins in the region. BASINS models were calibrated and validated using historic flow and water quality data from 1991 to 2006. The goodness-of-fit for the calibrated hydrology, suspended sediment, and orthophosphate models was high, with coefficients of determination ranging from 0.72 to 0.93 in the calibration period. The calibrated models were run under a range of eight downscaled climate change, two regional land use change, and four combined scenarios. Results included average increases in winter flows of ten percent, decreases in summer flows of thirty-seven percent, and increases in fifth percentile flows of up to eighty percent as a result of climate change in the Tualatin River Basin. For land use change, the results included an increase in annual flows of twenty-one percent for the development-oriented scenario and a decrease of sixteen percent for the conservation-oriented scenario, with amplified changes at the sub-basin scale, including more than doubled winter flow. For combined scenarios of climate change and urban development, there is a projected increase in winter flows of up to seventy-one percent and decrease in summer flows of up to forty-eight percent. Changes in suspended sediment and orthophosphate loading broadly tracked hydrological changes, with winter increases and summer decreases. The results are relevant to regional planners interested in the long-term response of water resources to climate change and land use change at the basin scale. Title: Impacts of Climate Change and Urban Development on Water Resources in the Tualatin River Basin Author: Praskievicz, Sarah Year: 2009 Potential impacts of climate change on the water resources of the Pacific Northwest of the United States include earlier peak runoff, reduced summer flows, and increased winter flooding. An increase in impervious surfaces, accompanied by urban development, is known to decrease infiltration and increase surface runoff. Alterations of flow amount and pathways can alter water quality through dilution or flushing effects. I used the United States Environmental Protection Agency's Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) modeling system to investigate the relative importance of future climate change and land use change in determining the quantity and quality of freshwater resources in north western Oregon's Tualatin River Basin. The basin was chosen for this study because it is rapidly urbanizing and representative of other low-elevation basins in the region. BASINS models were calibrated and validated using historic flow and water quality data from 1991 to 2006. The goodness-of-fit for the calibrated hydrology, suspended sediment, and orthophosphate models was high, with coefficients of determination ranging from 0.72 to 0.93 in the calibration period. The calibrated models were run under a range of eight downscaled climate change, two regional land use change, and four combined scenarios. Results included average increases in winter flows of ten percent, decreases in summer flows of thirty-seven percent, and increases in fifth percentile flows of up to eighty percent as a result of climate change in the Tualatin River Basin. For land use change, the results included an increase in annual flows of twenty-one percent for the development-oriented scenario and a decrease of sixteen percent for the conservation-oriented scenario, with amplified changes at the sub-basin scale, including more than doubled winter flow. For combined scenarios of climate change and urban development, there is a projected increase in winter flows of up to seventy-one percent and decrease in summer flows of up to forty-eight percent. Changes in suspended sediment and orthophosphate loading broadly tracked hydrological changes, with winter increases and summer decreases. The results are relevant to regional planners interested in the long-term response of water resources to climate change and land use change at the basin scale. Close

• 5. [Article] The Effects of Climate Change and Urbanization on the Runoff of the Rock Creek Basin

  Climate changes brought on by global warming are expected to have a significant affect on the Pacific Northwest hydrology during the 21st Century. Current research anticipates higher mean annual temperatures ...

  Citation × Citation Citation Abstract Copy Title: The Effects of Climate Change and Urbanization on the Runoff of the Rock Creek Basin Author: Franczyk, Jon J. Year: 2008 Climate changes brought on by global warming are expected to have a significant affect on the Pacific Northwest hydrology during the 21st Century. Current research anticipates higher mean annual temperatures and an intensification of the hydrological cycle. This is of particular concern for highly urbanized basins, which are considered more vulnerable to changes in climate. Because the majority of previous studies have addressed the influences of either climate or urban land cover changes on runoff, there is a lack of research investigating the combined effect of these factors. The Rock Creek basin (RCB), located in the Portland, OR, metropolitan area, has been experiencing rapid urban growth throughout the last 30 years, making it an ideal study area for assessing the affect of climate and land cover changes on runoff. Methods for this assessment include using a combination of climate change and land cover change scenarios for 2040 with the semi distributed AVSWAT-X (Arc View Soil and Water Assessment Tool) hydrological model to determine changes in mean runoff depths at the monthly, seasonal, and annual scales. Statistically downscaled climate change results from the ECHAM5 general circulation model (GCM) found that the region would experience an increase of 1.2°C in the average annual temperature and a 6% increase in average annual precipitation between 2030 and 2059. The model results revealed an amplification of runoff from either climate or urbanization. Projected climate change plus low-density, sprawled urban development for 2040 produced the greatest change to mean annual runoff depth (+5.5%), while climate change plus higher-density urban development for 2040 resulted in the smallest change (+5.3%), when compared to the climate and land cover of 2001. The results of this study support the hypothesis that the combination of both climate change and urbanization would amplify the runoff from the RCB during the 21st Century. This has significant implications for water resource managers attempting to implement adaptive water resource policies to future changes resulting from climate and urbanization. Title: The Effects of Climate Change and Urbanization on the Runoff of the Rock Creek Basin Author: Franczyk, Jon J. Year: 2008 Climate changes brought on by global warming are expected to have a significant affect on the Pacific Northwest hydrology during the 21st Century. Current research anticipates higher mean annual temperatures and an intensification of the hydrological cycle. This is of particular concern for highly urbanized basins, which are considered more vulnerable to changes in climate. Because the majority of previous studies have addressed the influences of either climate or urban land cover changes on runoff, there is a lack of research investigating the combined effect of these factors. The Rock Creek basin (RCB), located in the Portland, OR, metropolitan area, has been experiencing rapid urban growth throughout the last 30 years, making it an ideal study area for assessing the affect of climate and land cover changes on runoff. Methods for this assessment include using a combination of climate change and land cover change scenarios for 2040 with the semi distributed AVSWAT-X (Arc View Soil and Water Assessment Tool) hydrological model to determine changes in mean runoff depths at the monthly, seasonal, and annual scales. Statistically downscaled climate change results from the ECHAM5 general circulation model (GCM) found that the region would experience an increase of 1.2°C in the average annual temperature and a 6% increase in average annual precipitation between 2030 and 2059. The model results revealed an amplification of runoff from either climate or urbanization. Projected climate change plus low-density, sprawled urban development for 2040 produced the greatest change to mean annual runoff depth (+5.5%), while climate change plus higher-density urban development for 2040 resulted in the smallest change (+5.3%), when compared to the climate and land cover of 2001. The results of this study support the hypothesis that the combination of both climate change and urbanization would amplify the runoff from the RCB during the 21st Century. This has significant implications for water resource managers attempting to implement adaptive water resource policies to future changes resulting from climate and urbanization. Close

• 6. [Article] Future Flooding Impacts on Transportation Infrastructure and Traffic Patterns Resulting from Climate Change

  This study investigated potential impacts of climate change on travel disruption resulting from road closures in two urban watersheds in the Portland metropolitan area. We used ensemble climate change ...

  Citation × Citation Citation Abstract Copy Title: Future Flooding Impacts on Transportation Infrastructure and Traffic Patterns Resulting from Climate Change Author: Chang, Heejun, Lafrenz, Martin, Jung, Il-Won, Figliozzi, Miguel A., Melgoza, Rolando, Ruelas, David, Platman, Deena, Pederson, Cindy Year: 2011 This study investigated potential impacts of climate change on travel disruption resulting from road closures in two urban watersheds in the Portland metropolitan area. We used ensemble climate change scenarios, a hydrologic model, stream channel survey, a hydraulic model, and a travel forecast model to develop an integrated impact assessment method. High-resolution climate change scenarios are based on the combinations of two emission scenarios and eight general circulation models. The Precipitation-Runoff Modeling System was calibrated and validated for the period 1988-2006, and simulated for determining the probability of floods from 2020-2049. We surveyed stream cross sections at five road crossings for stream channel geometry and determined floodwater surface elevations using the HEC-RAS model. Four of the surveyed bridges and roadways were lower in elevation than the current 100-year floodwater surface elevation, leading to relatively frequent nuisance flooding. These roadway flooding events will become more frequent under some climate change scenarios in the future, but climate change impacts will depend on local geomorphic conditions. While vehicle miles traveled were not significantly affected by road closure, vehicle-hours delay demonstrated a greater impact from road closures, increasing by 10 percent in the Fanno Creek area. Results indicate that any cost analysis is extremely sensitive to the occurrence of human fatalities or injuries and fairly insensitive to delay costs. In addition, this research presents a comprehensive classification of flooding costs, identifies preventative measures, and makes short- and long-term recommendations. Our research demonstrated the usefulness of the integration of top-down and bottom-up approaches in climate change impact assessment, and the need for spatially explicit modeling and participatory planning in flood management and transportation planning under increasing climate uncertainty. Title: Future Flooding Impacts on Transportation Infrastructure and Traffic Patterns Resulting from Climate Change Author: Chang, Heejun, Lafrenz, Martin, Jung, Il-Won, Figliozzi, Miguel A., Melgoza, Rolando, Ruelas, David, Platman, Deena, Pederson, Cindy Year: 2011 This study investigated potential impacts of climate change on travel disruption resulting from road closures in two urban watersheds in the Portland metropolitan area. We used ensemble climate change scenarios, a hydrologic model, stream channel survey, a hydraulic model, and a travel forecast model to develop an integrated impact assessment method. High-resolution climate change scenarios are based on the combinations of two emission scenarios and eight general circulation models. The Precipitation-Runoff Modeling System was calibrated and validated for the period 1988-2006, and simulated for determining the probability of floods from 2020-2049. We surveyed stream cross sections at five road crossings for stream channel geometry and determined floodwater surface elevations using the HEC-RAS model. Four of the surveyed bridges and roadways were lower in elevation than the current 100-year floodwater surface elevation, leading to relatively frequent nuisance flooding. These roadway flooding events will become more frequent under some climate change scenarios in the future, but climate change impacts will depend on local geomorphic conditions. While vehicle miles traveled were not significantly affected by road closure, vehicle-hours delay demonstrated a greater impact from road closures, increasing by 10 percent in the Fanno Creek area. Results indicate that any cost analysis is extremely sensitive to the occurrence of human fatalities or injuries and fairly insensitive to delay costs. In addition, this research presents a comprehensive classification of flooding costs, identifies preventative measures, and makes short- and long-term recommendations. Our research demonstrated the usefulness of the integration of top-down and bottom-up approaches in climate change impact assessment, and the need for spatially explicit modeling and participatory planning in flood management and transportation planning under increasing climate uncertainty. Close