Physical Sciences and Mathematics Commons^™

Forest Fire Effects On Snow Storage And Melt Across Scales Of Forest Recovery In The Western Oregon Cascades, Megan Nicole Guinn

Dissertations and Theses

Snow is the largest component of water storage in the western United States, it serves as a key moisture source for forested ecosystems and is fundamentally linked to streamflow and nutrient cycling. Snow is vulnerable to climatic warming, and a key consequence of declining mountain snowpack is the escalation in wildfire frequency, extent, intensity, and duration across the seasonal snow zone. Fire modifies the spatial extent of snow in watersheds, reducing snow water storage and timing of melt across burned forests. Forested mountain ecosystems and water supplies are facing shifts in their structure, function, and succession. Previous research has focused …

Structure-From-Motion Derived Snow Cover In Burned Forests Of The Western Oregon Cascades, Siobhan Ciafone

Dissertations and Theses

Forest fire occurrence in the western US has increased rapidly since the 1980s, and most western US fires occur in the seasonal snow zone. Burned forests influence snow accumulation and melt patterns for years following fire, and understanding drivers of variability in snow cover across a burned landscape at the basin-scale is necessary for accurate hazard prediction and water resource forecasting. Basin-scale surveys of snowpack are possible with remote sensing, but accurate sensing methods such as Light Detection and Ranging (LiDAR) are often cost-prohibitive. In the last decade, structure-from-motion (SfM), an optical remote sensing technique, has emerged as an affordable …

Ce-Qual-W2 Performance Assessment Modeling 1979 Grh Flume Study, Logan Negherbon

Civil and Environmental Engineering Master's Project Reports

In an early review of numerical reservoir hydrodynamic models, the US Army Corps of Engineers developed a physical model at the US Army Waterways Experiment Station to assess the performance of modeling cold water underflow with numerous 2-dimensional and 3-dimensional numerical hydrodynamic models. Within this effort, the precursor for CE-QUAL-W2, the Laterally Averaged Reservoir Model, was defined and applied with limited success in representing the vertical velocity profile and outflow temperatures series collected from the physical model in the General Reservoir Hydrodynamics flume. CE-QUAL-W2 has since been modified from this early form in numerous ways including incorporation of higher order …

Spatial Analysis Of Burn Severity And Streamflow Response In The Western Conus, Will Brendan Long

Dissertations and Theses

Wildfire increases the magnitude of runoff in catchments, which can lead to the degradation of ecosystems, risk to infrastructure, and loss of life. The Labor Day Fires of 2020 provided an opportunity to compare multiple large and severe wildfires with the objective of determining potential changes to hydrologic processes in Oregon Cascades watersheds. Geographic information systems (GIS) were implemented to determine the total percentage burned and percentage of high burn severity class of six watersheds on the west-slope of the Oregon Cascade Range. In addition, two control watersheds were included to contrast the influence of climatic effects. Spatial arrangement of …

Post-Fire Erosional And Hydrological Processes Promoting Debris Flow Initiation In A Douglas Fir And Western Hemlock Forest In The Riverside Burn Area, Oregon, Morena Nicole Hammer

Dissertations and Theses

Post-fire debris flows initiated by overland flow in the Pacific Northwest (PNW) are largely undocumented. Instead, debris flows are typically initiated by shallow landslides that result in a mud slurry of water and sediments traveling downhill under the force of gravity. However, because of the Fall 2020 fires in Oregon, the typical initiation style and erosional patterns in burned catchments may have changed because of unusually high burn severity. Due to the intensity of these fires, we set out to determine how hydrologic processes and erosion occurred, when they occurred, and what process was primarily responsible for the erosion that …

Learning From Machines: Insights In Forest Transpiration Using Machine Learning Methods, Morgan Tholl

Dissertations and Theses

Machine learning has been used as a tool to model transpiration for individual sites, but few models are capable of generalizing to new locations without calibration to site data. Using the global SAPFLUXNET database, 95 tree sap flow data sites were grouped using three clustering strategies: by biome, by tree functional type, and through use of a k-means unsupervised clustering algorithm. Two supervised machine learning algorithms, a random forest algorithm and a neural network algorithm, were used to build machine learning models that predicted transpiration for each cluster. The performance and feature importance in each model were analyzed and compared …

Spatial And Seasonal Variations Of Microplastic Concentrations In Portland's Freshwater Ecosystems, Rebecca Talbot

Dissertations and Theses

Microplastics are a pollutant of growing concern and are ubiquitous in a variety of environmental compartments. The majority of microplastics research to date has been conducted in marine waters, and less is known regarding the sources and delivery pathways of microplastics in urban rivers. The first chapter is comprised of a review of the scientific literature regarding the spatial and temporal factors affecting global freshwater microplastic distributions and abundances. Microplastic spatial distributions are heavily influenced by anthropogenic factors, with higher concentrations reported in regions characterized by urban land cover, high population density, and wastewater treatment plant effluent. Temporal variables of …

A Study Of Stable Isotopes In Snow On Mt. Hood, Oregon, Maya Felix

University Honors Theses

Over the 2020-2021 Winter, event-based and end-of-season snow samples were collected on Mt. Hood near Government Camp, OR and analyzed for their stable isotopic compositions of ¹⁸O and ²H. It was found that surficial snow collected through the winter had higher variation in isotopic values than samples from a snow pit collected in spring. This suggests homogenization occurred in the snowpack over the season from snow metamorphism, sublimation, and/or melting. Homogenization of the snowpack will likely become more pronounced as temperatures increase and rain falls more often than snow due to climate change. Research that utilizes the snowpack …

A Community Of Fear: Emotion And The Hydro-Social Cycle In East Porterville, Michael Egge

Geography Masters Research Papers

Broader governance challenges driving water insecurity globally are well documented in the literature, however the power-laden relationships and emotions that shape water access at the household and community levels are yet to be fully investigated, especially in the context of water consolidation projects. In this article, we examine the role of emotions in mediating access to water and in the production of resource struggles among marginalized communities existing outside of conventional regulatory frameworks. We bring together two relational approaches – the hydro-social cycle and emotional political ecology – to examine water insecurity and how it manifests in the historically disadvantaged …

Reassessing Hydrothermal Heat Discharge And The Relationship Of Hot Springs In The North Oregon Cascades, Aaron Alexander Orr

Dissertations and Theses

Reservoir temperatures of hydrothermal systems in the Pacific Northwest reflect the feasibility of geothermal energy production and the tectonic framework of the region. Multicomponent geothermometry techniques were applied to new and historic water chemistry data in the north-central Oregon Western Cascades and the lower Wind River Valley in southern Washington in order to recalculate reservoir temperatures. Revised reservoir temperatures, water chemistry, and isotope data were used to determine relationships between hot springs in the north-central Oregon Cascades. Geothermal reservoir temperatures were estimated for the lower Wind River Valley (98.44 ± 0.96°C) and for Austin and Bagby Hot Springs (100.10 ± …

An Investigation And Comparison Of Stable Isotopes In Meteoric Waters And Groundwaters From Southern Washington, Emily E. Smoot

University Honors Theses

A main source of freshwater in the Pacific Northwest is the Columbia River Basalt Group aquifer system. The semi-arid region of eastern Washington has undergone heavy groundwater depletion in recent decades due to increasing population and expanding agricultural use. Aggressive mining has resulted in drawdowns of up to 30 meters. By using stable isotopes oxygen-eighteen (¹⁸O) and deuterium (D), this study confines the timing of groundwater precipitation and proposes an explanation for why drawdowns are so significant. The isotopic composition of meteoric water is compared to groundwaters from southeast Washington. The two populations are statistically different (p < 0.001, alpha = 0.05). The isotopic composition of groundwaters from the deepest wells (< -150 m msl) are isotopically lighter than meteoric waters and not achievable by recharge under the current climate. These deep groundwaters are interpreted to have precipitated during the Last Glacial Maximum in the late Pleistocene and finished precipitating roughly 5 ka. Thus, replenishment of the aquifer cannot be expected to keep pace with extraction. Additionally, this research examines the elevation response in the stable isotope signature of meteoric water along the 47° N latitude by computing three lapse rates for ^{18 …}

Glacial Meltwater Modeling To Simulate Lake Water Budget (1996-2013) In Taylor Valley, Antarctica, Julian Michael Cross

Dissertations and Theses

The McMurdo Dry Valleys (MDV), the largest ice-free region (4,500 km²) in Antarctica, are a polar desert with an average annual temperature of -18ºC. In Taylor Valley, one of the MDV, closed-basin, perennially ice-covered lakes occupy the valley floor. Their water balance is controlled by inflow from glacial meltwater runoff and loss due to sublimation, making them sensitive indicators of climate. In this study, a physically-based model of glacier meltwater and lake ice sublimation is adapted to explain modern (1996 to 2013) lake-level variations. Meltwater model results were improved by the inclusion of MODIS remotely-sensed albedo measurements (E …

Annual And Seasonal Variation In Hydrologic Performance Of Ecoroofs Of Multiple Depths, Portland, Or, Ashley Michelle Baker

Dissertations and Theses

It is essential that cities adopt new approaches to stormwater management in the face of changing precipitation regime. In some locations, ecoroofs have been incorporated into city plans as a stormwater control measure, and thus their real-world performance under current conditions can assist with adequate planning. In this study rainfall retention data collected during a three year period, between 2014-2017, is analyzed for 75mm and 125mm ecoroof plots in Portland, Oregon, USA. There is no difference in annual rainfall retention performance between the shallower and deeper plots. However, the 36% mean annual retention of the ecoroof plots is a significant …

Hydrologic Trends And Spatial Relationships Of Stream Temperature And Discharge In Urbanizing Watersheds In The Portland Metropolitan Area Of The Pacific Northwest, Emma Lee Brenneman

Dissertations and Theses

This study explores various relationships of streamflow and stream temperature over the Portland Metropolitan area in two urbanizing watersheds. Four stream temperature and discharge metrics were derived from USGS stream gauges in the Tualatin River and Johnson Creek watersheds and were analyzed for monotonic trends. Additionally, this study explored the sensitivity of stream temperature to air temperature and streamflow to assess where locations throughout the watershed may be more sensitive to these changes. Relationships among stream temperature, air temperature, and streamflow were assessed using linear and nonlinear bivariate regression for yearly values and summer months. Additionally, this study seeks to …

Evaluating The Impact And Distribution Of Stormwater Green Infrastructure On Watershed Outflow, Benjamin Fahy

Dissertations and Theses

Green Stormwater Infrastructure (GSI) has become a popular method for flood mitigation as it can prevent runoff from entering streams during heavy precipitation. In this study, a recently developed neighborhood in Gresham, Oregon hosts a comparison of various GSI projects on runoff dynamics. The study site includes dispersed GSI (rain gardens, retention chambers, green streets) and centralized GSI (bioswales, detention ponds, detention pipes). For the 2017-2018 water year, hourly rainfall and observed discharge data is used to calibrate the EPA's Stormwater Management Model to simulate rainfall-runoff dynamics, achieving a Nash-Sutcliffe efficiency of 0.75 and Probability Bias statistic of 3.3%. A …

From Probabilistic Socio-Economic Vulnerability To An Integrated Framework For Flash Flood Prediction, Sepideh Khajehei

Dissertations and Theses

Flash flood is among the most hazardous natural disasters, and it can cause severe damages to the environment and human life. Flash floods are mainly caused by intense rainfall and due to their rapid onset (within six hours of rainfall), very limited opportunity can be left for effective response. Understanding the socio-economic characteristics involving natural hazards potential, vulnerability, and resilience is necessary to address the damages to economy and casualties from extreme natural hazards. The vulnerability to flash floods is dependent on both biophysical and socio-economic factors. This study provides a comprehensive assessment of socio-economic vulnerability to flash flood alongside …

Ensemble Data Assimilation For Flood Forecasting In Operational Settings: From Noah-Mp To Wrf-Hydro And The National Water Model, Mahkameh Zarekarizi

Dissertations and Theses

The National Water Center (NWC) started using the National Water Model (NWM) in 2016. The NWM delivers state-of-the-science hydrologic forecasts in the nation. The NWM aims at operationally forecasting streamflow in more than 2,000,000 river reaches while currently river forecasts are issued for 4,000. The NWM is a specific configuration of the community WRF-Hydro Land Surface Model (LSM) which has recently been introduced to the hydrologic community. The WRF-Hydro model, itself, uses another newly-developed LSM called Noah-MP as the core hydrologic model. In WRF-Hydro, Noah-MP results (such as soil moisture and runoff) are passed to routing modules. Riverine water level …

Multi-Dimensional Drought Risk Assessment Based On Socio-Economic Vulnerabilities And Hydro-Climatological Factors, Ali Ahmadalipour

Dissertations and Theses

Drought is among the costliest natural hazards developing slowly and affecting large areas, which imposes severe consequences on society and economy. Anthropogenic climate change is expected to exacerbate drought in various regions of the globe, making its associated socioeconomic impacts more severe. Such impacts are of higher concern in Africa, which is mainly characterized by arid climate and lacking infrastructure as well as social development. Furthermore, the continent is expected to experience vast population growth, which will make it more vulnerable to the adverse effects of drought. This study provides the first comprehensive multi-dimensional assessment of drought risk across the …

Turbidity Dynamics During High-Flow Storm Events In The Clackamas River, Oregon 2006-2012, Micelis Clyde Doyle

Dissertations and Theses

Turbidity is a useful parameter that can be utilized to help understand the water quality in a river and is an expression of the optical properties of a liquid that cause light rays to be scattered and absorbed rather than transmitted in straight lines. A total of 41 storm events occurring during water years 2006-2012 were analyzed for this study. A hysteresis index (HI) was used to assess the difference in turbidity on the rising and falling limbs of a storm-hydrograph. The upstream Carter Bridge site exhibited a clockwise (C) hysteresis in 38 of 41 storm events and counter-clockwise (CC) …

Detecting Change In Rainstorm Properties From 1977-2016 And Associated Future Flood Risks In Portland, Oregon, Alexis Kirsten Cooley

Dissertations and Theses

In response to increased greenhouse gases and global temperatures, changes to the hydrologic cycle are projected to occur and new precipitation characteristics are expected to emerge. The study of these characteristics is facilitated by common indices to measure precipitation and temperature developed by the Expert Team on Climate Change Detection and Indices (ETCCDI). These indices can be used to describe the likely consequences of climate change such as increased daily precipitation intensity (SDII) and heavier rainfall events (R95p). This study calculates a subset of these indices from observed and modelled precipitation data in Portland, Oregon. Five rainfall gages from a …

Analyzing Dam Feasibility In The Willamette River Watershed, Alexander Cameron Nagel

Dissertations and Theses

This study conducts a dam-scale cost versus benefit analysis in order to explore the feasibility of each the 13 U.S. Army Corps of Engineers (USACE) commissioned dams in Oregon’s Willamette River network. Constructed between 1941 and 1969, these structures function in collaboration to comprise the Willamette River Basin Reservoir System (WRBRS). The motivation for this project derives from a growing awareness of the biophysical impacts that dam structures can have on riparian habitats. This project compares each of the 13 dams being assessed, to prioritize their level of utility within the system. The study takes the metrics from the top …

Utilization Of Remote Sensing In Drought Monitoring Over Iraq, Yousif Almamalachy

Dissertations and Theses

Agricultural drought is a creeping disaster that overshadows the vegetative cover in general and cropland specifically in Iraq, a country that was well known for its agricultural production and fertile soil. In the recent years, the arable lands in Iraq experienced increasing land degradation that led to desertification, economic losses, food insecurity, and deteriorating environment. Remote sensing is employed in this study and four different indices are utilized, each of which is derived from MODIS satellite mission products. Agricultural drought maps are produced from 2003 to 2015 after masking the vegetation cover. Year 2008 was found the most severe drought …

Application Of Numerical Modeling To Study River Dynamics: Hydro-Geomorphological Evolution Due To Extreme Events In The Sandy River, Oregon, Sarkawt Hamarahim Muhammad

Dissertations and Theses

The Sandy River (OR) is a coastal tributary of the Columbia River and has a steep hydroshed 1316 square kilometers which is located on the western side of Mount Hood (elevation range 3 m to 1800 m). The system exhibits highly variable flow: Its average discharge is ~40 m³/s, and the highest recorded discharge was 1739 m³/s in 1964. In this study I model the geomorphic sensitivity of an 1800m reach located the downstream of the former Marmot Dam, which was removed in 2007. The hydro-geomorphic response to major flood has implications for system management and …

From Drought Monitoring To Forecasting: A Combined Dynamical-Statistical Modeling Framework, Hongxiang Yan

Dissertations and Theses

Drought is the most costly hazard among all natural disasters. Despite the significant improvements in drought modeling over the last decade, accurate provisions of drought conditions in a timely manner is still one of the major research challenges. In order to improve the current drought monitoring and forecasting skills, this study presents a hybrid system with a combination of remotely sensed data assimilation based on particle filtering and a probabilistic drought forecasting model. Besides the proposed drought monitoring system through land data assimilation, another novel aspect of this dissertation is to seek the use of data assimilation to quantify land …

Modeling Of Historic Columbia River Flood Impacts Based On Delft 3d Simulations, Lumas Terence Helaire

Dissertations and Theses

Natural and anthropogenic processes over the past 150 years have altered the bathymetry of the Lower Columbia River (LCR) and have changed the long wave propagation of tides and floods. Possible causes for the increase in tidal amplitudes (+7% in tidal range in Astoria) are decreases in river discharge, lengthening of the river channel due to the construction of jetties at the mouth, dredging and deepening of the shipping channel, and reduction of the tidal prism due to the filling and diking of tidal wetlands. In this study, changes in the characteristics of long waves are elucidated by developing two …

Hydrogeologic Investigation Of A Pumice Aquifer, Fremont/Winema National Forest, Oregon, Jonathan Michael Weatherford

Dissertations and Theses

The middle Holocene cataclysmic eruption of Mount Mazama blanketed Walker Rim, in south central Oregon, with 270 cm to 300 cm of pumice, causing capture of surface water systems by groundwater, stream relocation, and the formation of biologically diverse fens and seasonal wetlands. The pumice aquifer at Round Meadow, an 8.6 km² basin, hosts both a fen and seasonally ponded wetlands. The Round Meadow watershed lies within a closed basin between the upper Klamath and Deschutes river basins. As the highest meadow at Walker Rim, it is a relatively well-constrained system to study the effects of hydrological disruption.

A …

A Multivariate Modeling Approach For Generating Ensemble Climatology Forcing For Hydrologic Applications, Sepideh Khajehei

Dissertations and Theses

Reliability and accuracy of the forcing data plays a vital role in the Hydrological Streamflow Prediction. Reliability of the forcing data leads to accurate predictions and ultimately reduction of uncertainty. Currently, Numerical Weather Prediction (NWP) models are developing ensemble forecasts for various temporal and spatial scales. However, it is proven that the raw products of the NWP models may be biased at the basin scale; unlike model grid scale, depending on the size of the catchment. Due to the large space-time variability of precipitation, bias-correcting the ensemble forecasts has proven to be a challenging task. In recent years, Ensemble Pre-Processing …

Evaluating Global Sensitivity Analysis Methods For Hydrologic Modeling Over The Columbia River Basin, Maysoun Ayad Hameed

Dissertations and Theses

Global Sensitivity Analysis (GSA) approach helps to identify the effectiveness of model parameters or inputs and thus provides essential information about the model performance. The effects of 14 parameters and one input (forcing data) of the Sacramento Soil Moisture Accounting (SAC-SMA) model are analyzed by using two GSA methods: Sobol' and Fourier Amplitude Sensitivity Test (FAST). The simulations are carried out over five sub-basins within the Columbia River Basin (CRB) for three different periods: one-year, four-year, and seven-year. The main parameter sensitivities (first-order) and the interactions sensitivities (second-order) are evaluated in this study. Our results show that some hydrological processes …

Automatic Calibration Of Water Quality And Hydrodynamic Model (Ce-Qual-W2), Nasim Shojaei

Dissertations and Theses

One of the most important purposes of surface water resource management is to develop predictive models to assist in identifying and evaluating operational and structural measures for improving water quality. To better understand the effects of external and internal nutrient and organic loading and the effects of reservoir operation, a model is often developed, calibrated, and used for sensitivity and management simulations. The importance of modeling and simulation in the scientific community has drawn interest towards methods for automated calibration. This study addresses using an automatic technique to calibrate the water quality model CE-QUAL-W2 (Cole and Wells, 2013). CE-QUAL-W2 is …

Streamflow Modeling Of Johnson Creek Subwatersheds Using The Precipitation Runoff Modeling System, Theophilus Matthew Malone

Civil and Environmental Engineering Master's Project Reports

Johnson Creek, in the Portland, Oregon metropolitan region, has several pollutants on the U.S. Environmental Protection Agency's (EPA) 303(d) list including excess heat, low dissolved oxygen, and harmful bacteria. Understanding streamflow response to precipitation events is an important component to evaluating water quality trends and calculating the Total Maximum Daily Load (TMDL) for pollutants of concern. Investigating the streamflow-precipitation relationship on the subwatershed scale can give insight to the hydrologic response of a given watershed. However, developing rating curves for several subwatersheds can be cost and time prohibitive. The objective of this project was to develop a hydrologic model using …