An online survey of river restoration practitioners, engineers, and researchers was conducted to examine current practices and perspectives on how climate change is integrated into engineering designs for river restoration. Seventy-six responses were submitted to the survey. While the responses came from a wide range of demographies, respondents were most...
The re-introduction of large woody debris (LWD) into streams and rivers for stream restoration purposes is rapidly growing. Engineered log jams (ELJs) are man-made structures intended to mimic natural LWD structures, designed and installed to protect stream banks from erosion while increasing habitat diversity. Several studies have evaluated the flow...
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DesiréeD. Tullos
The re-introduction of large woody debris (LWD) into streams and rivers
Low-tech habitat restoration techniques, including Stage 0 treatments, are increasingly applied but often lack robust evaluation of their effects. In 2018, one kilometer of the South Fork McKenzie (SFMK) River, OR was modified to the Stage 0 condition for the benefit of ESA-listed Chinook by raising the incised channel to...
Proper use of vegetation in streambank bioengineering practices requires a comprehensive understanding of the influence of vegetation density on streambank hydraulics. A series of studies were conducted to investigate the relationship between independent variables vegetation density, bank angle, and discharge and dependent variables channel velocity, resistance, turbulence, and shear stress....
Estimating how large instream wood (LW) may impact local hydraulics is critical both for mitigating flood hazards and for ensuring intended habitat benefits of the LW are produced. In practice, the design of forms such as LW is limited by a lack of mechanistic tools for estimating how LW features...
This study assessed suitability of annelid habitats under current baseflow conditions and evaluated the mobility of suitable annelid substrates under a 2-year peak flushing flow. Outputs from a 2020 Bureau of Reclamation SRH-2D model were combined with field measurements of annelid presence/absence and habitat variables including depth, velocity and d50,...
Extreme, flood-producing precipitation events in mountains threaten human life and local and national economies. In the Himalayas, scarce meteorological data historically limited understanding of the underlying processes driving extreme events. However, the capacity to observe, measure and quantify precipitation on regional scales has increased tremendously over the last three decades...
Upper Klamath Lake (UKL) and Agency Lake in south-central Oregon are hypereutrophic due to phosphorus (P) loading from both geologic and agricultural sources in the watershed. Restoring historic lake-fringe wetlands to provide P sinks around the lakes has been accepted as a favorable means of reducing lake P levels and...
Multipurpose management of hydrosystems face a number of uncertainties related to hydrologic variability and nonstationarity. Anticipated air temperature increases in the Pacific Northwest region are projected to alter the timing and quantity of streamflow associated with precipitation shifting from snow to rain, including shorter winter runoff periods, earlier spring runoff,...
Floods remain the world’s most destructive natural hazard, despite centuries of efforts to minimize losses. Understanding public preferences for flood mitigation measures, and the impacts of these measures, is key to minimizing flood-induced losses. This study quantified tradeoffs between flood mitigation measures and determined factors that influence public preferences for...
Reed Canarygrass (RCG) is an aggressive invader in aquatic ecosystems that swiftly modifies the environment and decreases biodiversity. A physical model was used to investigate the mechanisms by which RCG spreads. Experimental trials were implemented to examine feedbacks between a mid-channel patch of the flexible RCG, hydraulics, and bedform evolution...
Even though cloudburst events in high mountain areas can be highly destructive and result in significant losses of life, little is known definitively about these flood events. An exact
understanding of the driving processes, typical precipitation rates, and impacts of cloudburst events remain uncertain. This study seeks to advance knowledge...
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DesiréeTullos
Even though cloudburst events in high mountain areas can be highly
This study examines different fate and transport processes of N and P based on uncultivated grass, contour crop, and livestock management across different topographies (i.e. 5% vs. 30% slope) found within the tropical mountains of volcanic pedogenesis in the Ambato river catchment. The hydrologic, cultural, and agricultural properties of the...
Estimating how large instream wood (LW) may impact local hydraulics is critical both for mitigating flood hazards and for ensuring intended habitat benefits of the LW are produced. In practice, the design of forms such as LW is limited by a lack of mechanistic tools for estimating how LW features...
Floating guidance structures are intended to promote safe in-stream passage for juvenile salmon migrating downstream through reservoirs. However, the ability of an engineered structure to guide fish to safe passage has been primarily tested either after large-scale implementation in existing reservoirs or in laboratory studies and computer simulations without live...
The majority of dam removals are small structures that are governed primarily by state and local bodies. The objective of this study is to characterize and evaluate the governance that has driven recent decisions to remove small dams. In the governance literature on small dam removals, three aspects remain unclear....
This study was conducted to determine if a time-integrated Phillips sampler was able to estimate sediment yield when compared to a reference produced by an automated sampler. Time-integrated samplers are easier to use, more cost effective, and can withstand storm events better than automated samplers, but are not designed to...
Reservoir drawdown is a management technique increasingly used in maintenance of aging infrastructure, decommissioning dams, and to promote the flushing of fish and sediment to downstream reaches. Erosional processes in the reservoir may result in excessive delivery of sediment to downstream habitats and infrastructure, a critical long-term consideration. Typically, numerical...
Upper Klamath Lake (UKL) and Agency Lake (AL) in southern Oregon are both hypereutrophic, in large part due to natural and anthropogenic loading of phosphorus (P), resulting in annual blooms of blue-green algae. Reduction of P loading to the lake is considered crucial to reduce the blue-green algae blooms, maintain...
Discussions around adapting water management systems to climate change often express the need to increase the flexibility and adaptive capacity of current systems, and to implement robust strategies going forth. While these topics lie at the center of many climate change discussions, transforming adaptation recommendations into tangible tools and information...
In the face of increasing demand for and reduced supplies of water, methods to augment water supply and storage capacity are becoming increasingly important. In some areas, this has taken the form of aquifer storage and recovery (ASR), which involves injecting water into a well during a time of water...
Management of small dams may have profound implications for the health and integrity of small rivers and freshwater diversity. Global indicators suggest future growth in the small hydropower sector, particularly in developing countries. As a renewable energy source, it is often presumed that small hydropower entails fewer and less severe...
Re-establishing connectivity is a primary restoration activity for enhancing the
recovery of migratory fishes, but actions are often limited by lack of funds and
understanding of the benefits of individual projects. The objective of this study was to
develop a Bayesian Network (BN) to assess priorities for restoration of aquatic...
The objective of this study was to evaluate the use of aerial photos as a substitute for multiple-year pre-removal field data to assess the downstream channel changes associated with a small dam removal. The Brownsville Dam, a 2.1 m tall concrete dam on the Calapooia River, Oregon, was removed in...
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DesireeD. Tullos
The objective of this study was to evaluate the use of aerial photos as a
Re-introduction of large wood for expanding hydraulic variability is an increasingly common practice, yet it is not yet known what elements of hydraulic variability are most beneficial to fish. In an experiment designed to emphasize the minimization of energy expenditure through controlled predation and drift, we investigated whether juvenile coho,...
Support for low-carbon energy and opposition to new large dams encourages global development of small hydropower facilities. This support is manifested in national and international energy and development policies designed to incentivize growth in the small hydropower sector while curtailing large dam construction. However, the preference of small to large...
Chiloquin Dam, located on the Sprague River in southern Oregon, was removed in August of 2008. The processing of the sediment stored behind the dam (composed primarily of sand and fines) and the resulting bedform changes have been examined using repeat cross section surveys, yearly bathymetric surveys, and surface sediment...
This research asserts that flood risk perception of individuals living in floodplains influences their preparedness for taking actions to protect themselves from flood hazards. The results of this research are backed up by quantitative analysis of survey responses of individuals living in floodplains of Corvallis, OR in the USA. The...
As dams approach the end of their useful life, there is need to predict where and how accumulated sediment will move following their removal to estimate impacts on aquatic habitat and infrastructure. Flume studies suggest that sediment pulses disperse in place for most dams, but it is hypothesized that a...
After over two decades of advocacy and planning, the four hydroelectric facilities on the Klamath River will be decommissioned and removed starting in 2023. Significant positive changes are expected to result, from reduced severity of Harmful Algal Blooms (HABs) to nearly a two-fold increase in accessible habitat for native salmonid...
Optimization of reservoir operation is involves various competing objectives for a scarce resource (water). To find the optimal operation of reservoirs, it is essential to consider multiple objectives simultaneously. There are various sources of uncertainty associated with the reservoir operation problem that should be considered as well.
The overarching goal...
This study examines stream channel erosion processes in a small urbanizing watershed influenced by deposits of the Columbia Basin catastrophic floods: Kelley Creek, a 12-km² tributary of Johnson Creek, located just east of Portland, Oregon. Information on landscape history, stream channels, and sediment dynamics was compiled. The effects of future...
Migration and spawning phenology of Pacific Salmon is linked to the hydroregime, and thought to be triggered by increases in river discharge and decreases in water temperature. However, little data exists that describes direct fine-scale linkages between the hydroregime and spawning in Coho Salmon. This study evaluated the spatial and...
Agrivoltaics, which integrates photovoltaic power production with agriculture in the same plot of land, has the potential to reduce land competition and crop irrigation. To optimize agrivoltaic systems for crop growth, energy pathways must be characterized. While solar panels shade the crops, they also emit longwave radiation. At the end...
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DesireeTullos, Committee Member, representing Department of Biological and Ecological
This study focuses on one widespread characteristic of poor soil quality: hydrophobic soil. Previous research has produced conclusive evidence to show that soil hydrophobicity is affected by soil organic matter (SOM) and soil water content (WC). Hydrophobicity that responds to changes in WC is a unique form of surface hydrophobicity...
The Willamette River Basin supports 70% of Oregon’s population and contains the richest native fish fauna in the state, (Hulse, Gregory, & Baker, 2002). The Basin is facing changes that stress its water management regimes. Is the Basin’s water management regime able to adapt in the face of these changes?...
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APPENDIX D: SUPPORT FOR WATER MANAGEMENT TOOLS ..................................... 173
Several reports related to dams and dam removal have been released this decade by non-governmental organizations including Dam Removal: Science and Decision Making by The Heinz Center which focused on small dams, since most of the dams removed to date as well as those likely to be removed in the...
Dams are known to impact river channels and ecosystems, both during their lifetime and in their decommissioning. In this study, we applied a before-after-control-impact design associated with two small dam removals to investigate abiotic and biotic recovery trajectories from both the elimination of the press disturbance associated with the presence...
Vegetation growing on the surface of a streambank has been shown to alter the shear stresses
applied to the boundary, but basic questions remain regarding the influence of vegetation and
streambank configurations on near-bank hydraulics. In the present study, Froude-scaled flume
experiments were used to investigate how changes in vegetation...
The decommissioning of dams, as an approach to restoring longitudinal connectivity and to managing aging infrastructure, presents valuable opportunities for organized study of channel responses to sediment pulses. Experiments with physical and numerical models suggest that rivers process coarse sediment pulses primarily through dispersion. In contrast, translation appears to be...
Reservoirs play a critically important role in supplying water for human uses. However, sedimentation limits storage capabilities and increases risk for aging infrastructure. The objectives of this paper are to synthesize both general sediment management strategies and past sediment management efforts in Taiwan in order to identify the barriers to...
Dam removal is an important management tool for addressing aging infrastructure, public and structural safety, restoration of river connectivity for migratory organisms and recreation, and habitat quality. However, planning for dam removals is constrained by the difficulty of cost estimation. To our knowledge, published data on dam removal plans, total...
Dams and reservoirs are important components of water resource management systems, but their operational sensitivity to streamflow variability may make them vulnerable to climate change. Climate change is likely to affect the magnitude and timing of streamflow, motivating the assessment of potential impacts on dams and reservoirs. Here I examine...
The installation of engineered log jams (ELJs) is a common river restoration practice, implemented to modify flow structure and increase hydraulic complexity for the benefit of streambank protection and fish habitat. However, few studies have directly assessed the effects of ELJs on flow structure and complexity. This study presents a...
The goal of this thesis is to identify the factors which have most significantly contributed to historical dam removals in the United States. The trend of increased dam removals over time is specifically analyzed for evidence that increased scarcity of environmental goods and services is motivating dam removals. A theoretical...
There is still scholarly debate on the impacts of large floods on the geomorphic evolution of mountain rivers. Understating the geomorphic effects of large flows in mountain rivers is challenging given the hydraulic complexity of these systems and the inherent unpredictability of large floods. Prior work has demonstrated that extreme...
Hydrologic processes within mineral flat wetlands, along with their
connections to groundwater and downstream surface water in lowland agricultural
catchments are poorly understood, particularly under different land uses. In the three
field studies included in this thesis, we examined infiltration, wetland hydroperiod,
groundwater recharge dynamics, surface runoff generation, and water...
Large wood (LW) pieces are recognized as an important habitat component for salmon freshwater habitat. As such, they are often used in stream habitat restoration practices despite a lack of knowledge about their impacts on spatial and temporal hydraulic characteristics relevant to fish habitat. In this thesis we present results...
A large, damaging earthquake in 1944 on a blind thrust fault caused 60 cm of surface rupture on the subsidiary La Laja fault and additional unmeasured growth of an associated backlimb fold. Both the fold and fault are components of the La Laja Fault System (LLFS) located 25 km northeast...
Mountain rivers are important aquatic ecosystems that regulate sediment and water delivery to higher order streams. While previous studies have debated the roles of hillslope and fluvial processes in driving change in channel morphology of mountain rivers, few have examined how these processes influence channel response over longer timescales. The...