Search

Search Results

• 1. [Article] Hydrologic Modeling in Dynamic Catchments: A Data Assimilation Approach

  The transferability of conceptual hydrologic models in time is often limited by both their structural deficiencies and adopted parameterizations. Adopting a stationary set of model parameters ignores biases ...

  Citation × Citation Citation Abstract Copy Title: Hydrologic Modeling in Dynamic Catchments: A Data Assimilation Approach Author: Pathiraja, Sahani Darshika, Sharma, Ashish, Marshall, Lucy, Moradkhani, Hamid Year: 2016 The transferability of conceptual hydrologic models in time is often limited by both their structural deficiencies and adopted parameterizations. Adopting a stationary set of model parameters ignores biases introduced by the data used to derive them, as well as any future changes to catchment conditions. Although time invariance of model parameters is one of the hallmarks of a high quality hydrologic model, very few (if any) models can achieve this due to their inherent limitations. It is therefore proposed to consider parameters as potentially time varying quantities, which can evolve according to signals in hydrologic observations. In this paper, we investigate the potential for Data Assimilation (DA) to detect known temporal patterns in model parameters from streamflow observations. It is shown that the success of the DA algorithm is strongly dependent on the method used to generate background (or prior) parameter ensembles (also referred to as the parameter evolution model). A range of traditional parameter evolution techniques are considered and found to be problematic when multiple parameters with complex time variations are estimated simultaneously. Two alternative methods are proposed, the first is a Multilayer approach that uses the EnKF to estimate hyperparameters of the temporal structure, based on apriori knowledge of the form of nonstationarity. The second is a Locally Linear approach that uses local linear estimation and requires no assumptions of the form of parameter nonstationarity. Both are shown to provide superior results in a range of synthetic case studies, when compared to traditional parameter evolution techniques. Title: Hydrologic Modeling in Dynamic Catchments: A Data Assimilation Approach Author: Pathiraja, Sahani Darshika, Sharma, Ashish, Marshall, Lucy, Moradkhani, Hamid Year: 2016 The transferability of conceptual hydrologic models in time is often limited by both their structural deficiencies and adopted parameterizations. Adopting a stationary set of model parameters ignores biases introduced by the data used to derive them, as well as any future changes to catchment conditions. Although time invariance of model parameters is one of the hallmarks of a high quality hydrologic model, very few (if any) models can achieve this due to their inherent limitations. It is therefore proposed to consider parameters as potentially time varying quantities, which can evolve according to signals in hydrologic observations. In this paper, we investigate the potential for Data Assimilation (DA) to detect known temporal patterns in model parameters from streamflow observations. It is shown that the success of the DA algorithm is strongly dependent on the method used to generate background (or prior) parameter ensembles (also referred to as the parameter evolution model). A range of traditional parameter evolution techniques are considered and found to be problematic when multiple parameters with complex time variations are estimated simultaneously. Two alternative methods are proposed, the first is a Multilayer approach that uses the EnKF to estimate hyperparameters of the temporal structure, based on apriori knowledge of the form of nonstationarity. The second is a Locally Linear approach that uses local linear estimation and requires no assumptions of the form of parameter nonstationarity. Both are shown to provide superior results in a range of synthetic case studies, when compared to traditional parameter evolution techniques. Close

• 2. [Article] Environmental Controls on the Landscape-Scale Biogeography of Stream Bacterial Communities

  We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested ...

  Citation × Citation Citation Abstract Copy Title: Environmental Controls on the Landscape-Scale Biogeography of Stream Bacterial Communities Author: Fierer, Noah, Morse, Jennifer L., Berthrong, Sean T., Bernhardt, Emily S., Jackson, Robert B. Year: 2007 We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with the relative distance between communities (Spearman's ρ = 0.66, P < 0.001) although there were other contributing factors, including the quality of the fine benthic organic matter and the amount of dissolved organic carbon and nitrogen in the stream water (P < 0.05 for each). There was no evidence of an effect of geographic distance on bacterial community composition, suggesting that dispersal limitation has little influence on the observed biogeographical patterns in streams across this landscape. Cloning and sequencing of small-subunit rRNA genes confirmed the DNA fingerprinting results and revealed strong shifts among bacterial groups along the pH gradient. With an increase in streamwater pH, the abundance of acidobacteria in the FBOM bacterial community decreased (from 71% to 38%), and the abundance of proteobacteria increased (from 11% to 47%). Together these results suggest that microorganisms, like “macro”-organisms, do exhibit biogeographical patterns at the landscape scale and that these patterns may be predictable based on biogeochemical factors. Title: Environmental Controls on the Landscape-Scale Biogeography of Stream Bacterial Communities Author: Fierer, Noah, Morse, Jennifer L., Berthrong, Sean T., Bernhardt, Emily S., Jackson, Robert B. Year: 2007 We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with the relative distance between communities (Spearman's ρ = 0.66, P < 0.001) although there were other contributing factors, including the quality of the fine benthic organic matter and the amount of dissolved organic carbon and nitrogen in the stream water (P < 0.05 for each). There was no evidence of an effect of geographic distance on bacterial community composition, suggesting that dispersal limitation has little influence on the observed biogeographical patterns in streams across this landscape. Cloning and sequencing of small-subunit rRNA genes confirmed the DNA fingerprinting results and revealed strong shifts among bacterial groups along the pH gradient. With an increase in streamwater pH, the abundance of acidobacteria in the FBOM bacterial community decreased (from 71% to 38%), and the abundance of proteobacteria increased (from 11% to 47%). Together these results suggest that microorganisms, like “macro”-organisms, do exhibit biogeographical patterns at the landscape scale and that these patterns may be predictable based on biogeochemical factors. Close

• 3. [Article] Thinning and in-stream wood recruitment in riparian second growth forests in coastal Oregon and the use of buffers and tree tipping as mitigation

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article is copyrighted by Northeast Forestry ...

  Citation × Citation Citation Abstract Copy Title: Thinning and in-stream wood recruitment in riparian second growth forests in coastal Oregon and the use of buffers and tree tipping as mitigation Author: Litschert, S. E., Reeves, Gordon, Pabst, Robert, Benda, Lee E. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article is copyrighted by Northeast Forestry University and Springer-Verlag. It is published by Springer. It can be found at: http://link.springer.com/journal/11676 Title: Thinning and in-stream wood recruitment in riparian second growth forests in coastal Oregon and the use of buffers and tree tipping as mitigation Author: Litschert, S. E., Reeves, Gordon, Pabst, Robert, Benda, Lee E. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article is copyrighted by Northeast Forestry University and Springer-Verlag. It is published by Springer. It can be found at: http://link.springer.com/journal/11676 Close

• 4. [Article] A systems classification of watersheds and streams

  Adequate management and scientific investigation of ecosystems depends on classification of landscape systems based on all significant bio-physical and associated cultural properties. The present classification ...

  Citation × Citation Citation Abstract Copy Title: A systems classification of watersheds and streams Author: McCullough, Dale A. Adequate management and scientific investigation of ecosystems depends on classification of landscape systems based on all significant bio-physical and associated cultural properties. The present classification is a hierarchical systems design that can be modeled in terms of a natural system interacting with its level-specific environment. A watershed system in this context is embedded in a landscape environment organized into, for example, zonal and regional systems. A system at any level is classified by its capacity and the capacity of its environment, capacity defining temporally the scope of possible system performances relative to the components, substrate, climate, biota, culture, and water. This theoretical framework for examining systems was translated into methods suitable for integrating the full capacities of watersheds and for displaying the discrete and continuous nature of watershed and stream system similarities. Classification of land to a sub-zonal level with a full capacity description coupled with analysis of watershed substrate variables provided an adequate representation of watershed capacity. This was demonstrated by empirical correlations of system, components described in the literature, and by the ability to predict soil properties from topographic characteristics of land facets that are formed on a grid system overlaid on the watershed. Watershed classes were shown to be a good surrogate for differentiation of stream classes. Watersheds were analyzed by facet on a grid system according to several substrate variables. Slope, aspect, altitude, radiation intensity on the winter solstice and equinox, and soil series occurrence by facet effectively sorted watershed and stream classes. These same classes were also revealed by a more extensive set of variables describing the statistical distribution of these primary variables and some variables describing topographic roughness, form, and drainage development. Spatial organization of the basin is a significant factor determining solar radiation distribution on slope facets and in segments of the drainage network. A gravity model of spatial organization of soils is potentially a useful model for stream reach performances, considering the reach environment as the upstream segment, network, and watershed system. Title: A systems classification of watersheds and streams Author: McCullough, Dale A. Adequate management and scientific investigation of ecosystems depends on classification of landscape systems based on all significant bio-physical and associated cultural properties. The present classification is a hierarchical systems design that can be modeled in terms of a natural system interacting with its level-specific environment. A watershed system in this context is embedded in a landscape environment organized into, for example, zonal and regional systems. A system at any level is classified by its capacity and the capacity of its environment, capacity defining temporally the scope of possible system performances relative to the components, substrate, climate, biota, culture, and water. This theoretical framework for examining systems was translated into methods suitable for integrating the full capacities of watersheds and for displaying the discrete and continuous nature of watershed and stream system similarities. Classification of land to a sub-zonal level with a full capacity description coupled with analysis of watershed substrate variables provided an adequate representation of watershed capacity. This was demonstrated by empirical correlations of system, components described in the literature, and by the ability to predict soil properties from topographic characteristics of land facets that are formed on a grid system overlaid on the watershed. Watershed classes were shown to be a good surrogate for differentiation of stream classes. Watersheds were analyzed by facet on a grid system according to several substrate variables. Slope, aspect, altitude, radiation intensity on the winter solstice and equinox, and soil series occurrence by facet effectively sorted watershed and stream classes. These same classes were also revealed by a more extensive set of variables describing the statistical distribution of these primary variables and some variables describing topographic roughness, form, and drainage development. Spatial organization of the basin is a significant factor determining solar radiation distribution on slope facets and in segments of the drainage network. A gravity model of spatial organization of soils is potentially a useful model for stream reach performances, considering the reach environment as the upstream segment, network, and watershed system. Close

• 5. [Article] Terra ; Vol. 3 No. 2 (Spring 2008)

  24 p.

  Citation × Citation Citation Abstract Copy Title: Terra ; Vol. 3 No. 2 (Spring 2008) Author: Houtman, Nicolas, Sherman, Lee, Valls, Andrew, Kaplan, Jonathan 24 p. Title: Terra ; Vol. 3 No. 2 (Spring 2008) Author: Houtman, Nicolas, Sherman, Lee, Valls, Andrew, Kaplan, Jonathan 24 p. Close

• 6. [Article] Hydrological parameters affecting overland flow in an agricultural watershed

  Surface and subsurface hydrological parameters affecting overland flow from cultivated land were studied in three small sub-watersheds located in the western foothills of the Willamette Valley. The sub-watersheds, which ...

  Citation × Citation Citation Abstract Copy Title: Hydrological parameters affecting overland flow in an agricultural watershed Author: Lowery, Birl Surface and subsurface hydrological parameters affecting overland flow from cultivated land were studied in three small sub-watersheds located in the western foothills of the Willamette Valley. The sub-watersheds, which ranged in size from 0.46 to 6.0-ha, were fall-planted to grass or small grain. The parameters studied were infiltration, rainfall, runoff and subsurface water measurements. Infiltration measurements were obtained monthly using a portable infiltrometer. Rainfall was measured with recording and non-recording rain gages. Runoff was monitored from the sub-watershed outlets and within the watersheds using H-flumes and erosion plots, respectively. Subsurface moisture conditions were monitored with wells, piezometers and tensiometers. Seasonal changes in soil surface and moisture conditions caused seasonal variations in steady state infiltration rates. Low antecedent moisture and fail cropping practices produced rough, highly permeable surfaces which resulted in a high steady state infiltration rate (6.8 cm/hr). Winter rains caused increased antecedent moisture and surface sealing, and the final infiltration rate was found to decreased to a low of 4.0 cm/hr. Decreased storm events in the spring caused cracks to develop in the crust producing infiltration rates similar to those of the fall. Saturated hydraulic conductivities, measured with core samples from different horizons indicated decreased hydraulic conductivities in lower horizons. In some cases the hydraulic conductivities were virtually zero in the Cr horizon. Bimodal pore desaturations were noted in unsaturated hydraulic conductivities measured by a continuous drainage method. Piezometers and tensiometers indicated positive pore water pressures above moisture flow impeding layers. Hydrostatic pressures developed after rainy seasons started, producing ephemeral perched water tables. Ephemeral perched water tables were at or near ground surfaces during storm periods, causing saturated surface conditions. In lower landscape positions the ephemeral water table intersected the soil surface producing seepage zones. Seepage areas produced runoff between and during storm periods from plots located in the lower landscape position. Runoff from plots in the lower landscape position occasionally exceeded that of plots in upper landscape position by more than 50%. Overland flow occurred in sub-watersheds when the ephemeral perched water table approached the soil surface. In some cases during large storm events, the water table surfaced in both the lower and upper landscape position. Usually the water table was close enough to the surface to cause saturated or near saturated surface conditions via capillary rise. Title: Hydrological parameters affecting overland flow in an agricultural watershed Author: Lowery, Birl Surface and subsurface hydrological parameters affecting overland flow from cultivated land were studied in three small sub-watersheds located in the western foothills of the Willamette Valley. The sub-watersheds, which ranged in size from 0.46 to 6.0-ha, were fall-planted to grass or small grain. The parameters studied were infiltration, rainfall, runoff and subsurface water measurements. Infiltration measurements were obtained monthly using a portable infiltrometer. Rainfall was measured with recording and non-recording rain gages. Runoff was monitored from the sub-watershed outlets and within the watersheds using H-flumes and erosion plots, respectively. Subsurface moisture conditions were monitored with wells, piezometers and tensiometers. Seasonal changes in soil surface and moisture conditions caused seasonal variations in steady state infiltration rates. Low antecedent moisture and fail cropping practices produced rough, highly permeable surfaces which resulted in a high steady state infiltration rate (6.8 cm/hr). Winter rains caused increased antecedent moisture and surface sealing, and the final infiltration rate was found to decreased to a low of 4.0 cm/hr. Decreased storm events in the spring caused cracks to develop in the crust producing infiltration rates similar to those of the fall. Saturated hydraulic conductivities, measured with core samples from different horizons indicated decreased hydraulic conductivities in lower horizons. In some cases the hydraulic conductivities were virtually zero in the Cr horizon. Bimodal pore desaturations were noted in unsaturated hydraulic conductivities measured by a continuous drainage method. Piezometers and tensiometers indicated positive pore water pressures above moisture flow impeding layers. Hydrostatic pressures developed after rainy seasons started, producing ephemeral perched water tables. Ephemeral perched water tables were at or near ground surfaces during storm periods, causing saturated surface conditions. In lower landscape positions the ephemeral water table intersected the soil surface producing seepage zones. Seepage areas produced runoff between and during storm periods from plots located in the lower landscape position. Runoff from plots in the lower landscape position occasionally exceeded that of plots in upper landscape position by more than 50%. Overland flow occurred in sub-watersheds when the ephemeral perched water table approached the soil surface. In some cases during large storm events, the water table surfaced in both the lower and upper landscape position. Usually the water table was close enough to the surface to cause saturated or near saturated surface conditions via capillary rise. Close

• 7. [Article] Rapid calibration of coastal streams to detect effects of roadbuilding

  This study data from the Alsea Watershed Study located approximately ten miles from the Pacific Ocean in the Oregon Coast Range. The purpose was to evaluate the effects of roadbuilding on storm flows in ...

  Citation × Citation Citation Abstract Copy Title: Rapid calibration of coastal streams to detect effects of roadbuilding Author: Gilleran, Dennis James This study data from the Alsea Watershed Study located approximately ten miles from the Pacific Ocean in the Oregon Coast Range. The purpose was to evaluate the effects of roadbuilding on storm flows in two experimental streams. One 138 acre watershed, Deer Creek II, was subjected to 3.5 percent treatment (roadbuilding); the other, Deer Creek III, has an area of 100 acres and received 6.7 percent treatment. A rapid calibration method based upon individual storm hydrographs was selected to evaluate the effect of roadbuilding. This method of calibration was chosen because: 1) only 2.5 years were available prior to treatment; 2) there were temporary losses of record; and 3) a relatively sensitive method of detecting change was needed. The parameters examined in this method are time-to-peak, height-of-rise, and peak discharge of the storm hydrograph. Every storm hydrograph was examined in the 2.5 year pre-treatment period and in the one year post-treatment period. The three parameters were obtained from all acceptable storm hydrographs. Regression was used to develop a relationship between the three parameters on Deer Creek II and III and the three corresponding parameters on Flynn Creek (control). Analyses of covariance were used to determine the significance of changes in slope and elevation of the regression lines. Significant changes were detected in time-to-peak and height-of rise on Deer Creek II, while significant changes were detected in height-of-rise and peak discharge on Deer Creek III. The changes observed were related to roadbuilding and storm size. Title: Rapid calibration of coastal streams to detect effects of roadbuilding Author: Gilleran, Dennis James This study data from the Alsea Watershed Study located approximately ten miles from the Pacific Ocean in the Oregon Coast Range. The purpose was to evaluate the effects of roadbuilding on storm flows in two experimental streams. One 138 acre watershed, Deer Creek II, was subjected to 3.5 percent treatment (roadbuilding); the other, Deer Creek III, has an area of 100 acres and received 6.7 percent treatment. A rapid calibration method based upon individual storm hydrographs was selected to evaluate the effect of roadbuilding. This method of calibration was chosen because: 1) only 2.5 years were available prior to treatment; 2) there were temporary losses of record; and 3) a relatively sensitive method of detecting change was needed. The parameters examined in this method are time-to-peak, height-of-rise, and peak discharge of the storm hydrograph. Every storm hydrograph was examined in the 2.5 year pre-treatment period and in the one year post-treatment period. The three parameters were obtained from all acceptable storm hydrographs. Regression was used to develop a relationship between the three parameters on Deer Creek II and III and the three corresponding parameters on Flynn Creek (control). Analyses of covariance were used to determine the significance of changes in slope and elevation of the regression lines. Significant changes were detected in time-to-peak and height-of rise on Deer Creek II, while significant changes were detected in height-of-rise and peak discharge on Deer Creek III. The changes observed were related to roadbuilding and storm size. Close

• 8. [Article] Salmon anchor habitat strategy : invited expert responses

  This document compiles written responses by experts in their respective fields to questions from the Salmon Anchor Habitat Work Group about the Salmon Anchor Habitat Strategy component of Oregon Department ...

  Citation × Citation Citation Abstract Copy Title: Salmon anchor habitat strategy : invited expert responses Author: Institute for Natural Resources, Oregon Department of Forestry This document compiles written responses by experts in their respective fields to questions from the Salmon Anchor Habitat Work Group about the Salmon Anchor Habitat Strategy component of Oregon Department of Forestry Northwestern Oregon State Forest Management Plan. Title: Salmon anchor habitat strategy : invited expert responses Author: Institute for Natural Resources, Oregon Department of Forestry This document compiles written responses by experts in their respective fields to questions from the Salmon Anchor Habitat Work Group about the Salmon Anchor Habitat Strategy component of Oregon Department of Forestry Northwestern Oregon State Forest Management Plan. Close

• 9. [Article] Salmon anchor habitats in northwest Oregon state forests : a review of the policy-making process.

  The purpose of this document is to provide the SAH Workgroup with a summary of SAH strategy development and identify issues that have arisen so that all work group members have a common understanding of ...

  Citation × Citation Citation Abstract Copy Title: Salmon anchor habitats in northwest Oregon state forests : a review of the policy-making process. Author: Behan, Jeff, Institute for Natural Resources The purpose of this document is to provide the SAH Workgroup with a summary of SAH strategy development and identify issues that have arisen so that all work group members have a common understanding of the context for their work. The second section discusses the background of state forests. Salmonid protection and restoration strategies and policies are summarized in the third section. In the fourth section Northwest Oregon forest planning relating to salmonids is reviewed. Stakeholder positions and concerns regarding the SAH strategy are discussed in the fifth section. A brief conclusion follows. Title: Salmon anchor habitats in northwest Oregon state forests : a review of the policy-making process. Author: Behan, Jeff, Institute for Natural Resources The purpose of this document is to provide the SAH Workgroup with a summary of SAH strategy development and identify issues that have arisen so that all work group members have a common understanding of the context for their work. The second section discusses the background of state forests. Salmonid protection and restoration strategies and policies are summarized in the third section. In the fourth section Northwest Oregon forest planning relating to salmonids is reviewed. Stakeholder positions and concerns regarding the SAH strategy are discussed in the fifth section. A brief conclusion follows. Close

• 10. [Article] A historical reconstruction and land use history of six tidal wetlands in Oregon

  Citation × Citation Citation Abstract Copy Title: A historical reconstruction and land use history of six tidal wetlands in Oregon Author: Hennessey, Jennifer Taylor Title: A historical reconstruction and land use history of six tidal wetlands in Oregon Author: Hennessey, Jennifer Taylor Close