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• 1. [Article] Characterizing Rain/snow Partitioning in Mountain Watersheds for Present-day and Future Projected Climates

  Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR.

  Citation × Citation Citation Abstract Copy Title: Characterizing Rain/snow Partitioning in Mountain Watersheds for Present-day and Future Projected Climates Author: Sproles, Eric A., Nolin, Anne W. Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Title: Characterizing Rain/snow Partitioning in Mountain Watersheds for Present-day and Future Projected Climates Author: Sproles, Eric A., Nolin, Anne W. Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Close

• 2. [Article] Climate Change Impact on Drought Risk and Uncertainty in the Willamette River Basin

  Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR.

  Citation × Citation Citation Abstract Copy Title: Climate Change Impact on Drought Risk and Uncertainty in the Willamette River Basin Author: Chang, Heejun, Jung, Il-Won Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Title: Climate Change Impact on Drought Risk and Uncertainty in the Willamette River Basin Author: Chang, Heejun, Jung, Il-Won Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Close

• 3. [Article] Regional Scale Modeling of Climate, Cryosphere, and Freshwater Discharge in Changing Coastal Mountain Environments

  The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier ...

  Citation × Citation Citation Abstract Copy Title: Regional Scale Modeling of Climate, Cryosphere, and Freshwater Discharge in Changing Coastal Mountain Environments Author: Beamer, Jordan P. The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier cover change on regional hydrology. The region is data-sparse and contains a complex assemblage of topography and land cover, including a system of mountain glaciers that are retreating at some of the highest rates on Earth. The high rates of runoff from precipitation and glacial melt delivered by coastal rivers influence ocean circulation patterns, rates of global sea level rise, and provide spawning habitat for the large salmon populations. Physically-based hydrological modeling of the major water budget components of the GOA, driven using historical reanalysis weather data and land cover, reveals that the modeled water budget components, particularly precipitation input, vary widely between commonly-used weather products. The majority of the large freshwater flux into the GOA is derived from distributed coastal streams rather than the large inland rivers. The modeled seasonal aggregated GOA hydrograph is dominated by the spring and early summer snowmelt, and supplemented by late summer glacial ice melt. Model results demonstrate good agreement with NASA Gravity Recovery and Climate Experiment (GRACE) satellite data in terms of annual amplitudes and long term losses (ice loss), and suggest that existing GRACE solutions, previously reported to represent glacier mass balance alone, are actually measuring the full water budget of land and ice surfaces. An ensemble of climate models and future emissions scenarios were paired with systematically altered land cover to test the sensitivity of the hydrologic system to changes in regional climate patterns and glacier coverage representative of late twenty first century conditions. Compared with the hindcast simulations, the model results forced with increased regional air temperatures and precipitation inputs and reduced glacier cover produce an increase in the annual GOA freshwater discharge volume. The seasonal GOA hydrograph is flattened due to increased winter runoff from more winter rainfall and less snow accumulation, and lower levels of snowmelt and glacier ice contribution. Large uncertainties exist in the direction of change in the glacier runoff component, primarily due to uncertainties that exist in predicting glacier response to climate change. Hydrological modeling with high resolution and inclusion of relevant physical processes can produce significantly improved products that are of high value to and in demand by numerous other scientific communities. However, the value and accuracy of the output from the hydrologic model is highly dependent on the weather forcing quality. Given the considerable importance of quality weather forcing for hydrologic modeling, it is imperative to assess the suitability of multiple products by evaluating local and regional performance and accounting for uncertainty. Additional efforts should be made to improve the spatial resolution of the reanalysis through downscaling and to strategically increase the number of weather stations at high elevations and incorporate that data into weather forcing datasets. Title: Regional Scale Modeling of Climate, Cryosphere, and Freshwater Discharge in Changing Coastal Mountain Environments Author: Beamer, Jordan P. The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier cover change on regional hydrology. The region is data-sparse and contains a complex assemblage of topography and land cover, including a system of mountain glaciers that are retreating at some of the highest rates on Earth. The high rates of runoff from precipitation and glacial melt delivered by coastal rivers influence ocean circulation patterns, rates of global sea level rise, and provide spawning habitat for the large salmon populations. Physically-based hydrological modeling of the major water budget components of the GOA, driven using historical reanalysis weather data and land cover, reveals that the modeled water budget components, particularly precipitation input, vary widely between commonly-used weather products. The majority of the large freshwater flux into the GOA is derived from distributed coastal streams rather than the large inland rivers. The modeled seasonal aggregated GOA hydrograph is dominated by the spring and early summer snowmelt, and supplemented by late summer glacial ice melt. Model results demonstrate good agreement with NASA Gravity Recovery and Climate Experiment (GRACE) satellite data in terms of annual amplitudes and long term losses (ice loss), and suggest that existing GRACE solutions, previously reported to represent glacier mass balance alone, are actually measuring the full water budget of land and ice surfaces. An ensemble of climate models and future emissions scenarios were paired with systematically altered land cover to test the sensitivity of the hydrologic system to changes in regional climate patterns and glacier coverage representative of late twenty first century conditions. Compared with the hindcast simulations, the model results forced with increased regional air temperatures and precipitation inputs and reduced glacier cover produce an increase in the annual GOA freshwater discharge volume. The seasonal GOA hydrograph is flattened due to increased winter runoff from more winter rainfall and less snow accumulation, and lower levels of snowmelt and glacier ice contribution. Large uncertainties exist in the direction of change in the glacier runoff component, primarily due to uncertainties that exist in predicting glacier response to climate change. Hydrological modeling with high resolution and inclusion of relevant physical processes can produce significantly improved products that are of high value to and in demand by numerous other scientific communities. However, the value and accuracy of the output from the hydrologic model is highly dependent on the weather forcing quality. Given the considerable importance of quality weather forcing for hydrologic modeling, it is imperative to assess the suitability of multiple products by evaluating local and regional performance and accounting for uncertainty. Additional efforts should be made to improve the spatial resolution of the reanalysis through downscaling and to strategically increase the number of weather stations at high elevations and incorporate that data into weather forcing datasets. Close

• 4. [Article] Hydrologic Response to Climate Change in the Sprague River Basin, Oregon

  Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR.

  Citation × Citation Citation Abstract Copy Title: Hydrologic Response to Climate Change in the Sprague River Basin, Oregon Author: Hay, Lauren E., Markstrom, Steven L., Risley, John Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Title: Hydrologic Response to Climate Change in the Sprague River Basin, Oregon Author: Hay, Lauren E., Markstrom, Steven L., Risley, John Year: 2011 Presented at The Oregon Water Conference, May 24-25, 2011, Corvallis, OR. Close

• 5. [Article] Carbon isotopes show snowpack acts as a valuable moisture subsidy to mountain forests in the Oregon Cascades

  This study examines climatological influences, particularly that of snowpack, on tree growth and stable carbon isotope discrimination (Δ¹³C) from ~1980 to 2013 at two sites located in the upper reaches ...

  Citation × Citation Citation Abstract Copy Title: Carbon isotopes show snowpack acts as a valuable moisture subsidy to mountain forests in the Oregon Cascades Author: Ratcliff, Christopher J. This study examines climatological influences, particularly that of snowpack, on tree growth and stable carbon isotope discrimination (Δ¹³C) from ~1980 to 2013 at two sites located in the upper reaches of the McKenzie River watershed of the Oregon Cascade Mountains. We tested the use of Δ¹³C values from latewood, corroborated by tree-ring width chronologies as precipitation proxies to develop correlations between moisture stress and climate variables. Tree species at each site included Douglas-fir and mountain hemlock. Interpolated meteorological and snowpack data included snow water equivalent (SWE), precipitation, atmospheric temperature, vapor pressure deficit (VPD), relative humidity (RH), and a metric estimating growing season length. Significant correlations between latewood Δ¹³C and winter SWE at each site indicated the importance of winter snowpack to our selected tree species (r = 0.35, r = 0.43). Late summer precipitation and relative humidity (RH) were also significantly correlated with Δ¹³C (r = 0.49, r = 0.46; r = 0.43, r = 0.44). High correlations at both sites reinforced that late summer VPD was the primary driver of Δ¹³C (r = - 0.67, r = -0.61), which is often associated with moisture stress. This was further supported by correlations between air temperature and Δ¹³C (r = -0.46, r = -0.47), which drives much of the variation in VPD. Growing season length also showed significance in mountain hemlocks at the site with longer average snowpack (r = -0.22, r = -0.44). Moisture supplied by spring snow melt is a seasonably limited resource, nonetheless both sites clearly showed that snowpack acts as a valuable moisture subsidy to coniferous mountain forests in the Oregon Cascades. This study acts as a useful case study for future investigations into the relationship between snowpack and forest health in the Pacific North West. Title: Carbon isotopes show snowpack acts as a valuable moisture subsidy to mountain forests in the Oregon Cascades Author: Ratcliff, Christopher J. This study examines climatological influences, particularly that of snowpack, on tree growth and stable carbon isotope discrimination (Δ¹³C) from ~1980 to 2013 at two sites located in the upper reaches of the McKenzie River watershed of the Oregon Cascade Mountains. We tested the use of Δ¹³C values from latewood, corroborated by tree-ring width chronologies as precipitation proxies to develop correlations between moisture stress and climate variables. Tree species at each site included Douglas-fir and mountain hemlock. Interpolated meteorological and snowpack data included snow water equivalent (SWE), precipitation, atmospheric temperature, vapor pressure deficit (VPD), relative humidity (RH), and a metric estimating growing season length. Significant correlations between latewood Δ¹³C and winter SWE at each site indicated the importance of winter snowpack to our selected tree species (r = 0.35, r = 0.43). Late summer precipitation and relative humidity (RH) were also significantly correlated with Δ¹³C (r = 0.49, r = 0.46; r = 0.43, r = 0.44). High correlations at both sites reinforced that late summer VPD was the primary driver of Δ¹³C (r = - 0.67, r = -0.61), which is often associated with moisture stress. This was further supported by correlations between air temperature and Δ¹³C (r = -0.46, r = -0.47), which drives much of the variation in VPD. Growing season length also showed significance in mountain hemlocks at the site with longer average snowpack (r = -0.22, r = -0.44). Moisture supplied by spring snow melt is a seasonably limited resource, nonetheless both sites clearly showed that snowpack acts as a valuable moisture subsidy to coniferous mountain forests in the Oregon Cascades. This study acts as a useful case study for future investigations into the relationship between snowpack and forest health in the Pacific North West. Close

• 6. [Article] Modeling Elevation-Dependent Snow Sensitivity to Climate Warming in the Data Sparse Eastern Oregon Cascades

  In the mountains of the Western US, shifts in the timing and magnitude of snow water equivalent (SWE) over the past century are well documented and attributed to climate warming, but the magnitude of sensitivity ...

  Citation × Citation Citation Abstract Copy Title: Modeling Elevation-Dependent Snow Sensitivity to Climate Warming in the Data Sparse Eastern Oregon Cascades Author: Cooper, Matthew Guy In the mountains of the Western US, shifts in the timing and magnitude of snow water equivalent (SWE) over the past century are well documented and attributed to climate warming, but the magnitude of sensitivity depends on elevation. We modeled the spatial distribution of SWE and its sensitivity to climate warming in the 1500 km² Upper Deschutes River Basin, Oregon, with a spatially distributed snowpack energy balance model forced by a gridded meteorological dataset. The forcing data, gridded at a spatial scale of 1/16°, were downscaled to a 100 m spatial-scale digital elevation model using two sets of temperature lapse rates, with and without bias-correction applied prior to downscaling. The bias-correction method adjusted the spatial patterns of temperature and precipitation in the 1/16° gridded data to match 30 arcsecond Parameter Regressions on Independent Slopes Model (PRISM) climate data. During production, the 1/16° temperature data was adjusted for the effect of elevation using a spatially uniform and temporally constant 6.5°C km⁻¹ lapse rate, whereas PRISM adjusts temperature for the effect of elevation using spatially and temporally variable lapse rates that are computed directly from regional weather station data. Thus, bias-correction implicitly adjusted the lapse rates in the 1/16° gridded data to match measured lapse rates. To test the effect of this implicit adjustment of the input data lapse rates vs. adjusting the lapse rates during downscaling, the 30 arcsecond bias-corrected data and 1/16o original data were each downscaled with 1) a spatially uniform and temporally constant 6.5°C km⁻¹ lapse rate, and 2) with monthly varying lapse rates computed from PRISM. Precipitation was downscaled with the same method for each case. This procedure produced four sets of 100 m spatial scale data used as input to the snow model. Model parameters that control empirical estimates of incoming irradiance and the partitioning of precipitation into rain and snow were estimated independently with each dataset to optimize the agreement between modeled and observed SWE. We then modeled the sensitivity (percent change) of basin SWE in response to +2°C and +4°C warming with each of the four downscaled datasets and their respective optimized parameters. Pre-calibration, modeled SWE for the historical climate period differed depending on bias correction and choice of downscaling lapse rates. Post-calibration, modeled SWE for the historical climate period did not differ depending on choice of lapse rates but substantial differences emerged between modeled SWE with the original and bias-corrected forcing data. Inter-forcing dataset differences in modeled SWE during the historical period were largely controlled by differences in estimates of longwave irradiance and temperature between datasets. For the warming scenarios, the SWE sensitivity differed significantly at all elevations between the bias-corrected and original data, but (as in the post-calibration historical period) did not depend on choice of lapse rates. At low to mid elevations, climate change impacts on snow were largely controlled by temperature-driven shifts from snowfall to rainfall, while at high elevations, precipitation variability controlled SWE sensitivity. With just a 2°C increase in temperature, peak snow accumulation occurred 20-30 days earlier and was 20-60% smaller, the length of the snow covered season decreased up to 50 days, and winter rainfall increased by 20-60%. With a 4°C increase, the shifts in timing were roughly doubled and the declines in snow and snowfall increased up to 80%. A 10% increase in precipitation had a negligible impact on basin-integrated declines, indicating that future precipitation variability has little chance of offsetting regional climate warming impacts on snow in the Oregon Cascades. These results highlight the challenges of modeling SWE in data sparse regions, the importance of bias correcting gridded meteorological forcing datasets for hydrologic modeling applications in regions of complex topography, and the strong temperature dependence of snow in the Oregon Cascades. Title: Modeling Elevation-Dependent Snow Sensitivity to Climate Warming in the Data Sparse Eastern Oregon Cascades Author: Cooper, Matthew Guy In the mountains of the Western US, shifts in the timing and magnitude of snow water equivalent (SWE) over the past century are well documented and attributed to climate warming, but the magnitude of sensitivity depends on elevation. We modeled the spatial distribution of SWE and its sensitivity to climate warming in the 1500 km² Upper Deschutes River Basin, Oregon, with a spatially distributed snowpack energy balance model forced by a gridded meteorological dataset. The forcing data, gridded at a spatial scale of 1/16°, were downscaled to a 100 m spatial-scale digital elevation model using two sets of temperature lapse rates, with and without bias-correction applied prior to downscaling. The bias-correction method adjusted the spatial patterns of temperature and precipitation in the 1/16° gridded data to match 30 arcsecond Parameter Regressions on Independent Slopes Model (PRISM) climate data. During production, the 1/16° temperature data was adjusted for the effect of elevation using a spatially uniform and temporally constant 6.5°C km⁻¹ lapse rate, whereas PRISM adjusts temperature for the effect of elevation using spatially and temporally variable lapse rates that are computed directly from regional weather station data. Thus, bias-correction implicitly adjusted the lapse rates in the 1/16° gridded data to match measured lapse rates. To test the effect of this implicit adjustment of the input data lapse rates vs. adjusting the lapse rates during downscaling, the 30 arcsecond bias-corrected data and 1/16o original data were each downscaled with 1) a spatially uniform and temporally constant 6.5°C km⁻¹ lapse rate, and 2) with monthly varying lapse rates computed from PRISM. Precipitation was downscaled with the same method for each case. This procedure produced four sets of 100 m spatial scale data used as input to the snow model. Model parameters that control empirical estimates of incoming irradiance and the partitioning of precipitation into rain and snow were estimated independently with each dataset to optimize the agreement between modeled and observed SWE. We then modeled the sensitivity (percent change) of basin SWE in response to +2°C and +4°C warming with each of the four downscaled datasets and their respective optimized parameters. Pre-calibration, modeled SWE for the historical climate period differed depending on bias correction and choice of downscaling lapse rates. Post-calibration, modeled SWE for the historical climate period did not differ depending on choice of lapse rates but substantial differences emerged between modeled SWE with the original and bias-corrected forcing data. Inter-forcing dataset differences in modeled SWE during the historical period were largely controlled by differences in estimates of longwave irradiance and temperature between datasets. For the warming scenarios, the SWE sensitivity differed significantly at all elevations between the bias-corrected and original data, but (as in the post-calibration historical period) did not depend on choice of lapse rates. At low to mid elevations, climate change impacts on snow were largely controlled by temperature-driven shifts from snowfall to rainfall, while at high elevations, precipitation variability controlled SWE sensitivity. With just a 2°C increase in temperature, peak snow accumulation occurred 20-30 days earlier and was 20-60% smaller, the length of the snow covered season decreased up to 50 days, and winter rainfall increased by 20-60%. With a 4°C increase, the shifts in timing were roughly doubled and the declines in snow and snowfall increased up to 80%. A 10% increase in precipitation had a negligible impact on basin-integrated declines, indicating that future precipitation variability has little chance of offsetting regional climate warming impacts on snow in the Oregon Cascades. These results highlight the challenges of modeling SWE in data sparse regions, the importance of bias correcting gridded meteorological forcing datasets for hydrologic modeling applications in regions of complex topography, and the strong temperature dependence of snow in the Oregon Cascades. Close

• 7. [Article] Development of a hydrologic model to explore impacts of climate change on water resources in the Big Wood Basin, Idaho

  In the Western United States where 50-70% of annual precipitation comes in the form of winter snowfall, water supplies may be particularly sensitive to a warming climate. We worked with a network of stakeholders ...

  Citation × Citation Citation Abstract Copy Title: Development of a hydrologic model to explore impacts of climate change on water resources in the Big Wood Basin, Idaho Author: Inouye, Allison Marshall In the Western United States where 50-70% of annual precipitation comes in the form of winter snowfall, water supplies may be particularly sensitive to a warming climate. We worked with a network of stakeholders in the Big Wood Basin, Idaho, to explore how climate change may affect water resources and identify strategies that may help mitigate the impacts. The 8,300 square kilometer region in central Idaho contains a mixture of public and private land ownership, a diversity of landcover ranging from steep forested headwaters to expansive desert shrublands to a concentrated area of urban development that has experienced a quadrupling of population since the 1970s. With nearly 60% of precipitation falling as winter snow, stakeholders expressed concern regarding the vulnerability of the quantity and timing of seasonal snowpack as well as surface water supplies used primarily for agricultural irrigation under projected climate change. Here, we achieve two objectives. The first is the development of a hydrologic model to represent the dynamics of the surface water system in the Big Wood Basin. We use the semi-distributed model Envision-Flow to represent surface water hydrology, reservoir operations, and agricultural irrigation. We calibrated the model using a multi-criteria objective function that considered three metrics related to streamflow and one metric related to snow water equivalent. The model achieved higher an efficiency of 0.74 for the main stem of the Big Wood River and 0.50 for the Camas Creek tributary during the validation period. The second objective is an analysis of the Big Wood Basin hydrology under alternative future climate scenarios. We forced the calibrated model with three downscaled CMIP5 climate model inputs representing a range of possible future conditions over the period 2010-2070. The climate models simulate an increase in basin average annual air temperature ranging from 1.6-5.7oC in the 2060s compared to the 1980-2009 average. The climate models show less of a clear trend regarding precipitation but in general, one model simulates precipitation patterns similar to historic, one is slightly wetter than historic, and one is slightly drier than historic by the mid-21st century. Under these future climate scenarios, the depth of April 1 SWE may decline by as much as 92% in the 2060s compared to the historic average. Mid to high elevations exhibit the largest reductions in SWE. Simulated streamflows show a shift in timing, with peak flows occurring up to three weeks earlier and center of timing from two to seven weeks earlier in the 2050-2069 period compared to the historic period. Reduced peak flows of 14-70% were simulated by mid-century. The simulated total annual streamflow, though, fell within the historic interquartile range for most years in the future period. These and other metrics considered suggest that the surface water hydrology of the Big Wood Basin is likely to be impacted by climate change. If the natural water storage provided by the annual snowpack is reduced and timing of streamflows shifts, water resource use and management may need to change in the future. This work provides a foundation from which to explore alternative management scenarios. The approach used here can be transferred to other watersheds to further assess how water resources may be affected by climate change. Title: Development of a hydrologic model to explore impacts of climate change on water resources in the Big Wood Basin, Idaho Author: Inouye, Allison Marshall In the Western United States where 50-70% of annual precipitation comes in the form of winter snowfall, water supplies may be particularly sensitive to a warming climate. We worked with a network of stakeholders in the Big Wood Basin, Idaho, to explore how climate change may affect water resources and identify strategies that may help mitigate the impacts. The 8,300 square kilometer region in central Idaho contains a mixture of public and private land ownership, a diversity of landcover ranging from steep forested headwaters to expansive desert shrublands to a concentrated area of urban development that has experienced a quadrupling of population since the 1970s. With nearly 60% of precipitation falling as winter snow, stakeholders expressed concern regarding the vulnerability of the quantity and timing of seasonal snowpack as well as surface water supplies used primarily for agricultural irrigation under projected climate change. Here, we achieve two objectives. The first is the development of a hydrologic model to represent the dynamics of the surface water system in the Big Wood Basin. We use the semi-distributed model Envision-Flow to represent surface water hydrology, reservoir operations, and agricultural irrigation. We calibrated the model using a multi-criteria objective function that considered three metrics related to streamflow and one metric related to snow water equivalent. The model achieved higher an efficiency of 0.74 for the main stem of the Big Wood River and 0.50 for the Camas Creek tributary during the validation period. The second objective is an analysis of the Big Wood Basin hydrology under alternative future climate scenarios. We forced the calibrated model with three downscaled CMIP5 climate model inputs representing a range of possible future conditions over the period 2010-2070. The climate models simulate an increase in basin average annual air temperature ranging from 1.6-5.7oC in the 2060s compared to the 1980-2009 average. The climate models show less of a clear trend regarding precipitation but in general, one model simulates precipitation patterns similar to historic, one is slightly wetter than historic, and one is slightly drier than historic by the mid-21st century. Under these future climate scenarios, the depth of April 1 SWE may decline by as much as 92% in the 2060s compared to the historic average. Mid to high elevations exhibit the largest reductions in SWE. Simulated streamflows show a shift in timing, with peak flows occurring up to three weeks earlier and center of timing from two to seven weeks earlier in the 2050-2069 period compared to the historic period. Reduced peak flows of 14-70% were simulated by mid-century. The simulated total annual streamflow, though, fell within the historic interquartile range for most years in the future period. These and other metrics considered suggest that the surface water hydrology of the Big Wood Basin is likely to be impacted by climate change. If the natural water storage provided by the annual snowpack is reduced and timing of streamflows shifts, water resource use and management may need to change in the future. This work provides a foundation from which to explore alternative management scenarios. The approach used here can be transferred to other watersheds to further assess how water resources may be affected by climate change. Close

• 8. [Article] Characterizing Linkages Between the Climate, Cryosphere, and Impacts on Run-of-River Hydropower in Data-Sparse Mountain Environments

  In many regions of the world, a significant portion of the surface water originates in mountain headwaters where the timing and magnitude of streamflow is largely dictated by the seasonal storage of precipitation ...

  Citation × Citation Citation Abstract Copy Title: Characterizing Linkages Between the Climate, Cryosphere, and Impacts on Run-of-River Hydropower in Data-Sparse Mountain Environments Author: Mosier, Thomas M. In many regions of the world, a significant portion of the surface water originates in mountain headwaters where the timing and magnitude of streamflow is largely dictated by the seasonal storage of precipitation as snowpack and long-term storage as glaciers. Accumulation, persistence, and melt of snow and ice are functions of the climate in which they exist and therefore respond to changes in that climate. One important use of water in many regions is for hydropower energy production. While reservoir-based hydropower infrastructure has some ability to absorb changes in timing of streamflow, run-of-river hydropower infrastructure does not. Thus, in assessing the economic feasibility of new or existing run-of-river infrastructure, it is important to account for potential impacts climate change may have over the lifetime of the project. Projecting impacts of climate change on surface water resources, and in particular on run-of-river hydropower resource potential, requires robustly characterizing the linkages between the climate, cryosphere, and streamflow. Two obstacles to increasing our understanding of mountain systems are the sparsity of observation data and complexity of weather patterns. The first part of my research addresses the issue of climate data availability in mountain regions through development of statistical models to characterize the high-spatial resolution distribution of historic and projected future precipitation and temperature. I demonstrate these climate products through projecting long-term changes in snowfall for the Alaska Range, Alps, Central Andes, and Himalaya-Karakoram-Hindu Kush ranges. I then present a framework for assessing conceptual cryosphere hydrology models and implement the framework for two long-term glacier study sites in Alaska, USA. Using this framework, I identify novel formulations for modeling the heat transfer and energy balance of snowpacks and glaciers that improve model robustness relative to the current generation of cryosphere hydrology models typically used in data-sparse mountain environments. I then demonstrate a method for understanding the impacts of projected future climate change on run-of-river hydropower resource potential, using Falls Creek in Oregon, USA as a test case. A core value of this work is producing models that can be straightforwardly applied to any region, thus decreasing the impacts of data disparities between regions on our ability to characterize climate change impacts on mountain regions. Title: Characterizing Linkages Between the Climate, Cryosphere, and Impacts on Run-of-River Hydropower in Data-Sparse Mountain Environments Author: Mosier, Thomas M. In many regions of the world, a significant portion of the surface water originates in mountain headwaters where the timing and magnitude of streamflow is largely dictated by the seasonal storage of precipitation as snowpack and long-term storage as glaciers. Accumulation, persistence, and melt of snow and ice are functions of the climate in which they exist and therefore respond to changes in that climate. One important use of water in many regions is for hydropower energy production. While reservoir-based hydropower infrastructure has some ability to absorb changes in timing of streamflow, run-of-river hydropower infrastructure does not. Thus, in assessing the economic feasibility of new or existing run-of-river infrastructure, it is important to account for potential impacts climate change may have over the lifetime of the project. Projecting impacts of climate change on surface water resources, and in particular on run-of-river hydropower resource potential, requires robustly characterizing the linkages between the climate, cryosphere, and streamflow. Two obstacles to increasing our understanding of mountain systems are the sparsity of observation data and complexity of weather patterns. The first part of my research addresses the issue of climate data availability in mountain regions through development of statistical models to characterize the high-spatial resolution distribution of historic and projected future precipitation and temperature. I demonstrate these climate products through projecting long-term changes in snowfall for the Alaska Range, Alps, Central Andes, and Himalaya-Karakoram-Hindu Kush ranges. I then present a framework for assessing conceptual cryosphere hydrology models and implement the framework for two long-term glacier study sites in Alaska, USA. Using this framework, I identify novel formulations for modeling the heat transfer and energy balance of snowpacks and glaciers that improve model robustness relative to the current generation of cryosphere hydrology models typically used in data-sparse mountain environments. I then demonstrate a method for understanding the impacts of projected future climate change on run-of-river hydropower resource potential, using Falls Creek in Oregon, USA as a test case. A core value of this work is producing models that can be straightforwardly applied to any region, thus decreasing the impacts of data disparities between regions on our ability to characterize climate change impacts on mountain regions. Close

• 9. [Article] Climate and streamflow trends in the Columbia River basin: evidence for ecological and engineering resilience to climate change

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Taylor & Francis and can be found at: http://www.tandfonline.com/toc/tato20/cur...

  Citation × Citation Citation Abstract Copy Title: Climate and streamflow trends in the Columbia River basin: evidence for ecological and engineering resilience to climate change Author: Hatcher, Kendra L., Jones, Julia A. This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Taylor & Francis and can be found at: http://www.tandfonline.com/toc/tato20/current#.UkoG0XfVGHc. Title: Climate and streamflow trends in the Columbia River basin: evidence for ecological and engineering resilience to climate change Author: Hatcher, Kendra L., Jones, Julia A. This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Taylor & Francis and can be found at: http://www.tandfonline.com/toc/tato20/current#.UkoG0XfVGHc. Close

• 10. [Article] A method for remotely monitoring glaciers with regional application to the Pacific Northwest

  An integrative method for monitoring glacier geometry change and mass balance is presented and applied to the Pacific Northwest, USA. Acting as a baseline for interpretation of future changes in glacier ...

  Citation × Citation Citation Abstract Copy Title: A method for remotely monitoring glaciers with regional application to the Pacific Northwest Author: Medley, Brooke An integrative method for monitoring glacier geometry change and mass balance is presented and applied to the Pacific Northwest, USA. Acting as a baseline for interpretation of future changes in glacier size and shape, we first derive a new inventory of regional glacier cover using remotely sensed data. To investigate current climate controls on glacier health, we next model glacier mass balance for select glaciers, incorporating glacier hypsometry results from our new remotely derived inventory. Model results are then used to interpret climate-glacier interactions through sensitivity analysis and the future impacts on glacier geometry. These steps when taken together create a method for remote monitoring of glacier health and dynamics that can be replicated globally. Inventory results derived from the Advanced Spaceborne Thermal Emission and Reflection Radiometer imagery for the Pacific Northwest indicate that both the North Cascades National Park (99.0 ± 5.0 km2) and the Cascade volcanoes of Washington and Oregon (96.0 ± 4.8 km2) contain similar ice coverage while glaciers of the Olympic Mountains account for only 37.3 ± 1.9 km2. Additionally, significant semi-annual variations in glacier coverage on the Cascade volcanoes highlight the need to consider recent mass balance variations when selecting satellite data for glacier inventorying. Modeling results provided insight into climate-glacier interactions. Model results from the study glaciers show a recent strengthening of the relationship between summer balance and the El Niño/Southern Oscillation (ENSO) from the mid-1980s to the present. The correlation strengthening between ENSO and summer temperatures around 1985 is manifested in our results through enhanced summer melt. However, the influence of the Pacific Decadal Oscillation (PDO) on balance fluctuations is more ambiguous, as the recent 1976/77 shift into a warm phase is weakly distinguishable at only one study glacier. Glacier sensitivity estimates for a 1° C rise in temperature range from -0.73 to -1.09 mw.e., decreasing with latitude; however, no discernible pattern of precipitation sensitivity exists. At South Cascade glacier, a 30% increase in winter precipitation could offset a 1° C rise in temperature. Glaciers further south require a >40% increase in winter precipitation to remain in balance. However, South Cascade is the only glacier of the four study glaciers that could not exist under a 2° C warming scenario as its accumulation area occupies very low elevations. We postulate that the sensitivity of South Cascade glacier does not change as rapidly as those of the remaining three glaciers as the glacier retreats, making it the most vulnerable to climate change. Title: A method for remotely monitoring glaciers with regional application to the Pacific Northwest Author: Medley, Brooke An integrative method for monitoring glacier geometry change and mass balance is presented and applied to the Pacific Northwest, USA. Acting as a baseline for interpretation of future changes in glacier size and shape, we first derive a new inventory of regional glacier cover using remotely sensed data. To investigate current climate controls on glacier health, we next model glacier mass balance for select glaciers, incorporating glacier hypsometry results from our new remotely derived inventory. Model results are then used to interpret climate-glacier interactions through sensitivity analysis and the future impacts on glacier geometry. These steps when taken together create a method for remote monitoring of glacier health and dynamics that can be replicated globally. Inventory results derived from the Advanced Spaceborne Thermal Emission and Reflection Radiometer imagery for the Pacific Northwest indicate that both the North Cascades National Park (99.0 ± 5.0 km2) and the Cascade volcanoes of Washington and Oregon (96.0 ± 4.8 km2) contain similar ice coverage while glaciers of the Olympic Mountains account for only 37.3 ± 1.9 km2. Additionally, significant semi-annual variations in glacier coverage on the Cascade volcanoes highlight the need to consider recent mass balance variations when selecting satellite data for glacier inventorying. Modeling results provided insight into climate-glacier interactions. Model results from the study glaciers show a recent strengthening of the relationship between summer balance and the El Niño/Southern Oscillation (ENSO) from the mid-1980s to the present. The correlation strengthening between ENSO and summer temperatures around 1985 is manifested in our results through enhanced summer melt. However, the influence of the Pacific Decadal Oscillation (PDO) on balance fluctuations is more ambiguous, as the recent 1976/77 shift into a warm phase is weakly distinguishable at only one study glacier. Glacier sensitivity estimates for a 1° C rise in temperature range from -0.73 to -1.09 mw.e., decreasing with latitude; however, no discernible pattern of precipitation sensitivity exists. At South Cascade glacier, a 30% increase in winter precipitation could offset a 1° C rise in temperature. Glaciers further south require a >40% increase in winter precipitation to remain in balance. However, South Cascade is the only glacier of the four study glaciers that could not exist under a 2° C warming scenario as its accumulation area occupies very low elevations. We postulate that the sensitivity of South Cascade glacier does not change as rapidly as those of the remaining three glaciers as the glacier retreats, making it the most vulnerable to climate change. Close