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• 1. [Article] Assessing Mechanisms of Climate Change Impact on the Upland Forest Water Balance of the Willamette River Basin, Oregon

  Projected changes in air temperature, precipitation, and vapor pressure for the Willamette River Basin (Oregon, USA) over the next century will have significant impacts on the river basin water balance, ...

  Citation × Citation Citation Abstract Copy Title: Assessing Mechanisms of Climate Change Impact on the Upland Forest Water Balance of the Willamette River Basin, Oregon Author: Turner, David P., Conklin, David R., Vache, Kellie B., Schwartz, Cynthia, Nolin, Anne, Chang, Heejun, Watson, Eric, Bolte, John P. Year: 2016 Projected changes in air temperature, precipitation, and vapor pressure for the Willamette River Basin (Oregon, USA) over the next century will have significant impacts on the river basin water balance, notably on the amount of evapotranspiration (ET). Mechanisms of impact on ET will be both direct and indirect, but there is limited understanding of their absolute and relative magnitudes. Here, we developed a spatially explicit, daily time-step, modeling infrastructure to simulate the basin-wide water balance that accounts for meteorological influences, as well as effects mediated by changing vegetation cover type, leaf area, and ecophysiology. Three CMIP5 climate scenarios (Lowclim, Reference, and HighClim) were run for the 2010–2100 period. Besides warmer temperatures, the climate scenarios were characterized by wetter winters and increasing vapor pressure deficits. In the mid-range Reference scenario, our landscape simulation model (Envision) projected a continuation of forest cover on the uplands but a threefold increase in area burned per year. A decline (12–30%) in basin-wide mean leaf area index (LAI) in forests was projected in all scenarios. The lower LAIs drove a corresponding decline in ET. In a sensitivity test, the effect of increasing CO2 on stomatal conductance induced a further substantial decrease (11–18%) in basin-wide mean ET. The net effect of decreases in ET and increases in winter precipitation was an increase in annual streamflow. These results support the inclusion of changes in land cover, land use, LAI, and ecophysiology in efforts to anticipate impacts of climate change on basin-scale water balances. Title: Assessing Mechanisms of Climate Change Impact on the Upland Forest Water Balance of the Willamette River Basin, Oregon Author: Turner, David P., Conklin, David R., Vache, Kellie B., Schwartz, Cynthia, Nolin, Anne, Chang, Heejun, Watson, Eric, Bolte, John P. Year: 2016 Projected changes in air temperature, precipitation, and vapor pressure for the Willamette River Basin (Oregon, USA) over the next century will have significant impacts on the river basin water balance, notably on the amount of evapotranspiration (ET). Mechanisms of impact on ET will be both direct and indirect, but there is limited understanding of their absolute and relative magnitudes. Here, we developed a spatially explicit, daily time-step, modeling infrastructure to simulate the basin-wide water balance that accounts for meteorological influences, as well as effects mediated by changing vegetation cover type, leaf area, and ecophysiology. Three CMIP5 climate scenarios (Lowclim, Reference, and HighClim) were run for the 2010–2100 period. Besides warmer temperatures, the climate scenarios were characterized by wetter winters and increasing vapor pressure deficits. In the mid-range Reference scenario, our landscape simulation model (Envision) projected a continuation of forest cover on the uplands but a threefold increase in area burned per year. A decline (12–30%) in basin-wide mean leaf area index (LAI) in forests was projected in all scenarios. The lower LAIs drove a corresponding decline in ET. In a sensitivity test, the effect of increasing CO2 on stomatal conductance induced a further substantial decrease (11–18%) in basin-wide mean ET. The net effect of decreases in ET and increases in winter precipitation was an increase in annual streamflow. These results support the inclusion of changes in land cover, land use, LAI, and ecophysiology in efforts to anticipate impacts of climate change on basin-scale water balances. Close

• 2. [Article] Urban Water as a Coupled System: Interactions and Feedbacks Among Climate, Land Cover, Water Governance

  This presentation focuses on the changes in urban water systems and includes information on the relationship between water quality and property value, changes in land cover and dissolved oxygen, spatial ...

  Citation × Citation Citation Abstract Copy Title: Urban Water as a Coupled System: Interactions and Feedbacks Among Climate, Land Cover, Water Governance Author: Chang, Heejun Year: 2013 This presentation focuses on the changes in urban water systems and includes information on the relationship between water quality and property value, changes in land cover and dissolved oxygen, spatial variations of water temperature, and the need for integrative water and land planning. Title: Urban Water as a Coupled System: Interactions and Feedbacks Among Climate, Land Cover, Water Governance Author: Chang, Heejun Year: 2013 This presentation focuses on the changes in urban water systems and includes information on the relationship between water quality and property value, changes in land cover and dissolved oxygen, spatial variations of water temperature, and the need for integrative water and land planning. Close

• 3. [Article] Hydrologic Impacts of Climate Change in the Upper Clackamas River Basin, Oregon, USA

  The Pacific Northwest of the USA is dependent on seasonal snowmelt for water resources that support its economy and aquatic ecosystems. Increased temperatures resulting from higher concentrations of atmospheric ...

  Citation × Citation Citation Abstract Copy Title: Hydrologic Impacts of Climate Change in the Upper Clackamas River Basin, Oregon, USA Author: Graves, David, Chang, Heejun Year: 2007 The Pacific Northwest of the USA is dependent on seasonal snowmelt for water resources that support its economy and aquatic ecosystems. Increased temperatures resulting from higher concentrations of atmospheric greenhouse gases may cause disruptions to these resources because of reductions in the annual snowpack and the earlier occurrence of seasonal snowmelt. We applied a Geographic Information System (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 (UCB; located near Portland, Oregon, USA). Once validated using historic flow data, the model was run for 2 future time periods (2010–2039 and 2070–2099) using climate change simulations from 2 global circulation modelling groups (HadCM2 from the Hadley Centre for Climate Prediction and Research, and CGCM1 from the Canadian Centre for Climate Modelling and Analysis) as inputs. The model runs projected 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 in mean winter runoff by 2070–2099 vary from moderate (13.7%) to large (46.4%), depending on the changes to precipitation projected by the general circulation models (GCMs). 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 in similar studies of the entire Columbia River Basin, presumably because the elevations of much of the Upper Clackamas Basin are near the current mid-winter snow line. Title: Hydrologic Impacts of Climate Change in the Upper Clackamas River Basin, Oregon, USA Author: Graves, David, Chang, Heejun Year: 2007 The Pacific Northwest of the USA is dependent on seasonal snowmelt for water resources that support its economy and aquatic ecosystems. Increased temperatures resulting from higher concentrations of atmospheric greenhouse gases may cause disruptions to these resources because of reductions in the annual snowpack and the earlier occurrence of seasonal snowmelt. We applied a Geographic Information System (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 (UCB; located near Portland, Oregon, USA). Once validated using historic flow data, the model was run for 2 future time periods (2010–2039 and 2070–2099) using climate change simulations from 2 global circulation modelling groups (HadCM2 from the Hadley Centre for Climate Prediction and Research, and CGCM1 from the Canadian Centre for Climate Modelling and Analysis) as inputs. The model runs projected 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 in mean winter runoff by 2070–2099 vary from moderate (13.7%) to large (46.4%), depending on the changes to precipitation projected by the general circulation models (GCMs). 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 in similar studies of the entire Columbia River Basin, presumably because the elevations of much of the Upper Clackamas Basin are near the current mid-winter snow line. Close