Physical Sciences and Mathematics Commons^™

Exploring The Potential Impacts Of Climate Change On North America's Laurentian Great Lakes Tourism Sector, Natalie Chin

Open Access Dissertations

Climate change is one of the major challenges facing the global hospitality and tourism sector in the coming century and, given the important role that weather and climate play in all aspects of the tourism experience, tourism businesses owners need to start thinking about and enacting climate change adaptation strategies now. This work has utilized a combination of social science and physical science methods to (1) understand how the Great Lakes tourism sector could be impacted by climate change and (2) provide some insights into how researchers can help business owners prepare for these potential impacts. Overall, the results of …

Hydrocode Modeling Of Oblique Impacts Into Terrestrial Planets, Jordan D. Kendall

Open Access Dissertations

The abundance of moderately siderophile elements (“iron-loving”; e.g., Co, Ni) in the Earth’s mantle is 10 to 100 times larger than predicted by chemical equilibrium between silicate melt and iron at low pressure, but it does match expectation for equilibrium at high pressure and temperature. Recent studies of differentiated planetesimal impacts assume that planetesimal cores survive the impact intact as concentrated masses that passively settle from a zero initial velocity and undergo turbulent entrainment in a global magma ocean; under these conditions, cores greater than 10 km in diameter do not fully mix without a sufficiently deep magma ocean. I …

Miocene-Pliocene Strike-Slip Basin Development Along The Denali Fault System In The Eastern Alaska Range: Chronostratigraphy And Provenance Of The Mccallum Formation And Implications For Displacement, Wai Kehadeezbah Allen

Open Access Theses

The Denali fault system represents one of the major strike-slip faults in North America but very little is known about the amount and timing of displacement on this 2000-km-long structure. The 7.9 M 2002 Denali Earthquake emphasized the importance of this fault system for understanding the deformational record of the upper plate of the southern Alaska convergent margin. Our analysis of the Miocene-Pliocene McCallum Formation located along the east-central part of the Denali fault provides one of the few records for Neogene displacement as well as changes in surface and basin processes related to tectonic transport. We have established a …

Modeling The Impact Of Land Surface Feedbacks On Post Landfall Tropical Cyclones, Subashini Subramanian

Open Access Dissertations

The land surface is an important component of numerical models. The land surface models are modules that control energy partitioning, compute surface exchange coefficients and form the only physical boundary in a regional scale numerical model. Thus, an accurate representation of land surface is critical to compute surface fluxes, represent the boundary layer evolution and affect changes in weather systems. Land surface can affect landfalling tropical cyclones in two ways: (i) when the cyclone is offshore and land can influence cyclones by introducing dry (or moist) air that can weaken (or strengthen) the organized convective structure of cyclones, and (ii) …

Unraveling The Fingerprints Of Nox Using Stable Isotopes: Implications For Nox Source Partitioning And Oxidation Chemistry, Wendell William Walters

Open Access Dissertations

The nitrogen (N) and oxygen (O) stable isotope composition (δ15N & δ18O) of nitrogen oxides (NOx )may be a useful tool for constraining NOx emission sources as well as for understanding the atmospheric oxidation pathways responsible for its removal if various NOx sources and sink processes exhibit characteristic isotopic compositions (“fingerprints”). However, this requires (1) an accurate and complete inventory of δ15N(NOx) values from major emission sources, (2) an assessment of the kinetic and equilibrium isotope effects that can impact δ15N and δ18O values of NOx, (3) and test these assumptions by conducting accurate in situ δ15N and δ18O measurements …

An Examination Of Geographic Patterns Of Soil Climate And Its Classification In The U.S. System Of Soil Taxonomy, Hans Edwin Winzeler

Open Access Dissertations

Soil climate, the record of temporal patterns of soil moisture and temperature, is an important component of the structure of U.S. Soil Taxonomy. The U.S. Soil Survey has used the Newhall Simulation Model (NSM) for estimating soil climate from atmospheric climate records at weather stations since the 1970s. The current soil climate map of the U.S. was published in 1994 by using NSM runs from selected weather stations along with knowledge-based hand-drawn mapping procedures. We developed a revised soil climate mapping methodology using the NSM and digital soil mapping techniques.

The new methodology is called Grid Element Newhall Simulation Model …

Investigation Of Ambient Seismic Noise Using Seismic Interferometry In The Midwestern United States, Joshua Dakota Boschelli

Open Access Theses

The portion of the North American craton occupied by the Midwestern United States is a cratonic platform, where a veneer of Phanerozoic sedimentary strata buries the Precambrian basement up to 7 km. Due to the sediment cover and low topographic relief, the at depth structure of the region remains poorly understood. This region is of particular interest because over the past half-billion years tectonic forces have resulted in the formation of epeirogenic provinces in a stable cratonic interior. Using the OIINK flexible seismic array and the Earthscope Transportable Array, Ambient Seismic Noise Tomography was applied to investigate the crustal structure …

The Role Of The Picuris Orogeny In The Tectonic Evolution Of Proterozoic North America, Ruth Frances Aronoff

Open Access Dissertations

North America is a continent that has grown over time by horizontal attachment of material onto its margins. Studying the process of continental growth in the geologic past gives insight into fundamental components of plate tectonics, and sheds light onto processes at work at modern plate boundaries, in which mid- and lower-crustal rocks are generally hidden from view.

This study focuses on the growth of North America during the Proterozoic. Researchers have debated the role of three orogenies in shaping the southwestern margin of North America: the ∼1.80-1.60 Ga Yavapai and Mazatzal orogenies, and the newly recognized ∼1.40 Ga Picuris …

Simulation Of Flow And Water Quality From Tile Drains At The Watershed And Field Scale, Colleen Moloney

Open Access Theses

Simulation models such as the Soil and Water Assessment Tool (SWAT) have become widely used in determining the water quality impacts of various management practices. Ensuring that the algorithms accurately represent the processes simulated has become an important goal. Tile drainage is a standard practice in the Midwest, US in order to reduce risk of yield loss due to excess water. Multiple tile drainage and water table algorithms have been available in the SWAT model between the initial SWAT release and revision 638 used in this study. Testing of those algorithms is often limited. Furthermore, algorithms in the current version …

Role Of River Bathymetry In Hydraulic Modeling Of River Channels, Sayan Dey

Open Access Theses

Accurate geometric representation of the river channel is required for accurate hydraulic modeling of rivers. These are generally obtained through remote sensing techniques such as Light Detection and Ranging (LIDAR). However, these techniques lack the ability to model the submerged channel bed effectively and need to be complemented with surveyed bathymetric data for complete representation of the channel bathymetry, which can be time and cost prohibitive. An alternative to address this issue is to develop conceptual models that can estimate bathymetry.

This study aims to evaluate the potential of a conceptual model, the River Channel Morphology Model (RCMM) which estimates …

Seismic Body-Wave Interferometry Using Noise Autocorrelations For Crustal Structure And A Tutorial On 3d Seismic Processing And Imaging Using Madagascar, Can Oren

Open Access Theses

Seismic body-wave interferometry is applied to selected seismic stations from the USArray Earthscope Transportable Array (TA) by autocorrelating ambient seismic noise recordings to construct effective zero-offset reflection seismograms. The robustness of the auto-correlations of noise traces is first tested on a TA station in Nevada where body-wave reflections similar to those found in an earlier study are identified. This approach is then applied to several TA stations in the central U.S., and the results are compared with synthetic data. Different stacking time periods are then examined to find the shortest time intervals that provide stable correlation stacks.

A tutorial on …

Investigation Of Climate Variability And Climate Change Impacts On Corn Yield In The Eastern Corn Belt, Usa, Ruoyu Wang

Open Access Dissertations

The increasing demand for both food and biofuels requires more corn production at global scale. However, current corn yield is not able to meet bio-ethanol demand without jeopardizing food security or intensifying and expanding corn cultivation. An alternative solution is to utilize cellulose and hemi-cellulose from perennial grasses to fulfill the increasing demand for biofuel energy. A watershed level scenario analysis is often applied to figure out a sustainable way to strike the balance between food and fuel demands, and maintain environment integrity. However, a solid modeling application requires a clear understanding of crop responses under various climate stresses. This …

Effect Of Bioenergy Crops And Fast Growing Trees On Hydrology And Water Quality In The Little Vermilion River Watershed, Tian Guo

Open Access Dissertations

Energy security and sustainability require a suite of biomass crops, including woody species. Short rotation woody crops (SRWCs) such as Populus have great potential as biofuel feedstocks. Quantifying biomass yields of bioenergy crop and hydrologic and water quality responses to growth is important should it be widely planted in the Midwestern U.S. Subsurface tile drainage systems enable the Midwest area to become highly productive agricultural lands, but also create environmental problems like nitrate-N contamination of the water it drains. The Soil and Water Assessment Tool (SWAT) has been used to model watersheds with tile drainage, but the new tile drainage …

Crop Modeling For Assessing And Mitigating The Impacts Of Extreme Climatic Events On The Us Agriculture System, Zhenong Jin

Open Access Dissertations

The US agriculture system is the world’s largest producer of maize and soybean, and typically supplies more than one-third of their global trading. Nearly 90% of the US maize and soybean production is rainfed, thus is susceptible to climate change stressors such as heat waves and droughts. Process-based crop and cropping system models are important tools for climate change impact assessments and risk management. As data- science is becoming a new frontier for agriculture growth, the incoming decade calls for operational platforms that use hyper-local growth monitoring, high-resolution real-time weather and satellite data assimilation and cropping system modeling to help …

Present Day Plate Boundary Deformation In The Caribbean And Crustal Deformation On Southern Haiti, Steeve Symithe

Open Access Dissertations

The Caribbean plate and its boundaries with North and South America, marked by subduction and large intra-arc strike-slip faults, are a natural laboratory for the study of strain partitioning and interseismic plate coupling in relation to large earth- quakes. In this work, I use the available campaign and continuous GPS measurements in the Caribbean to derive a regional velocity field expressed in a consistent reference frame. I use this velocity field as input to a kinematic model where surface velocities result from the rotation of rigid blocks bounded by locked faults accumulating inter- seismic strain, while allowing for partial locking …

A History Of African And South American Basins, Rebecca A. Bobick

Open Access Theses

As hydrocarbon development in Africa and South America continues to expand, understanding the geologic evolution as well as the geologic symmetry of each of the continent's coastal basins grows increasingly important. Unfortunately, there's currently no comprehensive database that contains the stratigraphic record, depositional environments, and tectonic evolution available for either Africa or South America. Therefore, the goal of my research is to create an extensive datapack and guide booklet for Africa's major sedimentary basins, complete the South America datapack that's currently being constructed, and correlate the western African conjugate basins to the eastern South American conjugate basins. To accomplish this, …

Quantifying The Global N2o Emissions From Natural Ecosystems Using A Mechanistically-Based Biogeochemistry Model, Tong Yu

Open Access Theses

Nitrous oxide (N2O) has a great influence on atmospheric chemistry and climate. It is not only a major greenhouse gas, but also one of the largest ozone-depleting substances emitted from the biosphere. Process-based biogeochemistry modeling constrained by site-level observations is a feasible approach to quantifying its emissions at large temporal and spatial scales. This study developed a process-based biogeochemistry model of N2O emissions based on an extant biogeochemistry model, the Terrestrial Ecosystem Model (TEM). The model development includes: 1) incorporating the effects of physical conditions on both nitrification and denitrification and 2) implementing principles of the stoichiometry of carbon and …

Development And Evaluation Of A Watershed-Scale Hybrid Hydrologic Model, Younghyun Cho

Open Access Dissertations

A watershed-scale hybrid hydrologic model (Distributed-Clark), which is a lumped conceptual and distributed feature model, was developed to predict spatially distributed short- and long-term rainfall runoff generation and routing using relatively simple methodologies and state-of-the-art spatial data in a GIS environment. In Distributed-Clark, spatially distributed excess rainfall estimated with the SCS curve number method and a GIS-based set of separated unit hydrographs (spatially distributed unit hydrograph) are utilized to calculate a direct runoff flow hydrograph, and time-varied SCS CN values and conditional unit hydrograph approach for different runoff depth-based flow convolution are also used to compute long-term rainfall-runoff flow hydrographs. …

Watershed Delineation In The Field: A New Approach For Mobile Applications Using Lidar Elevation Data, Samuel Adam Noel

Open Access Theses

With the advancement of mobile devices, opportunities to take watershed management tasks out of the office and into the field can be realized. In turn, field workers can utilize these technologies to expedite the decision-making process so that they may focus on meeting with clients and addressing agricultural watershed management issues. High-resolution (∼1.5 m postspacing) elevation data gathered by light detection and ranging (LiDAR) provides the topographic detail necessary to model hydrology at the field-scale (∼1 km2).

Non-artifactual surface depressions lead to erroneous surface flow patterns when using existing algorithms. So a sequential depression-filling algorithm (SDFA) has been developed to …

Assessing Positional Accuracy And Correcting Point Data For Digital Soil Mapping At Varying Scales, Minerva J. Dorantes

Open Access Theses

Accuracy, timeliness, and the effect of scale of soil maps are rarely assessed. The recent increase in the use of GIS technologies and modelling software in natural resources and land management, has increased the demand for soil information at a finer resolution worldwide. Most of the world's developing countries rely on soils information at a scale that is too coarse for practical planning, and have obstacles impeding collection of new data, such as civil war and a lack of collection resources. The United States has an exhaustive collection of soils data at a fine scale. However, its location information is …

Evaluation Of Collapse Indicators For Seismically Vulnerable Reinforced Concrete Buildings, Nicholas R. Skok

Open Access Theses

Older reinforced concrete buildings can be prone to column shear and compression failures during earthquakes because of inadequate transverse reinforcement. Cities in seismic areas still have large inventories of older and potentially deficient buildings. To analyze every building and estimate its vulnerability in detail is costly. A simple method to rank quickly older buildings according to their seismic vulnerability is needed to help engineers prioritize the use of resources for rehabilitating the most vulnerable buildings.

Four indicators of building damage or collapse were evaluated using numerical analysis and prior data from building surveys: column index (Hassan & Sozen, 1997), R …

Systematic Analysis Of Drainage Events In Free Draining And Managed Subsurface Drainage Systems, Guy Bou Lahdou

Open Access Theses

Understanding the hydrologic controls that regulate outflow from free and managed subsurface drainage systems during drainage events can offer improved insight on the overall functioning and effectiveness of the systems so that they can be better managed or retrofitted to increase their environmental benefits. This study used drainage, precipitation, water table, and soil moisture data from a monitoring site located in east central Indiana to investigate the event hydrology of 22 drainage events in free and managed subsurface drainage systems. Relationships between event drainage volume, drain flow hydrograph metrics, column soil moisture, water table depth, and precipitation characteristics were explored …

Cosmogenic Beryllium Cycling In A Natural Forest Setting, Grace Conyers

Open Access Theses

10 Bemet , or cosmogenic beryllium, has a long half-life of 1.4 million years and quick adsorption on soil particles, which may make it ideal for dating soil erosion in historical context. However, there are questions on about the fundamental assumptions of the retentivity of 10 Bemet . This manuscript explores these assumptions and the context of nutrient cycling in a natural forest setting.

To see if 10 Bemet was being cycled through the trees, and at what rate, we looked at the[10 Bemet ] in the soil, 4 species of trees, and their leaves. The isotopic ratio 10 Be/9 …

The Geologic Framework Of Acoma Pueblo And Its Cultural Context: A Western & Native Perspective, Darryl Reano

Open Access Theses

The sequence of sedimentary rocks at Acoma Pueblo, New Mexico, are important both in terms of their cultural significance for the Native people of Acoma Pueblo and the insight they provide into the long term geologic history of the Colorado Plateau. In this thesis we present the first stratigraphic and provenance analysis of the Mesozoic strata at Acoma Pueblo, New Mexico, based on field observations and detrital zircon U-Pb geochronology. Acoma Pueblo was located in the distal part (i.e. backbulge) of a foreland basin system during most of the Mesozoic. Acoma Pueblo has not been included in previous regional studies …

Floodplain Mapping Using Soil Survey Geographic (Ssurgo) Database, Nikhil Sangwan

Open Access Theses

Floods are the most damaging of all natural disasters, adversely affecting millions of lives and causing financial losses worth billions of dollars every year across the globe. Flood inundation maps play a key role in assessment and mitigation of the potential flood hazards. However, there are several communities in the United States for which the flood risk maps have not been published yet, as the current flood inundation mapping methods are typically very expensive and time consuming. The objective of this study is to develop and examine an economical alternative approach to floodplain mapping using widely available soil survey data. …

Part I: Neoacadian To Alleghanian Foreland Basin Development And Provenance In The Central Appalachian Orogen, Pine Mountain Thrust Sheet Part Ii: Structural Configuration Of A Modified Mesozoic To Cenozoic Forearc Basin System, South-Central Alaska, Peter Benjamin Robertson

Open Access Theses

Foreland and forearc basins are large sediment repositories that form in response to tectonic loading and lithospheric flexure during orogenesis along convergent plate boundaries. In addition to their numerous valuable natural resources, these systems preserve important geologic information regarding the timing and intensity of deformation, uplift and erosion history, and subsidence history along collisional margins, and, in ancient systems, may provide more macroscopic information regarding climate, plate motion, and eustatic sea level fluctuations. This thesis presents two studies focused in the Paleozoic Appalachian foreland basin system along the eastern United States and in the Mesozoic to Cenozoic Matanuska forearc basin …

Peridynamic Modeling Of Coupled Mechanical Deformations And Transient Flow In Unsaturated Soils, Rami Jabakhanji

Open Access Dissertations

A coupled peridynamic model for mechanical deformations and transient moisture flow in unsaturated soils is developed. The model is capable of simulating the emergence and evolution of cracks triggered by volumetric strains in the soil which are associated with changes in moisture content. The development of our model is motivated by the need for a tool to analyze and evaluate the impact of dessication cracks on the movement of moisture and the mechanical properties of soils at the field scale. The model is based on the peridynamic reformulation of elasticity proposed by Silling for simulating the deformation of bodies with …

The Mechanism And Timescales Of Soil Formation In The Hyper-Arid Atacama Desert, Chile, Fan Wang

Open Access Dissertations

The planetary surfaces that evolve in the near absence of water are strikingly different from surfaces where water is abundant, but their formation is poorly documented. This research is an in-depth exemplary work in the Atacama Desert in northern Chile to understand the soil formation in hyper-arid environments, as an analog for planetary surfaces such as the Mars. In detail, the basic mechanism regarding the source material, timescale, paleo-climatic settings and the role of crypto-biotic crusts have been investigated to constrain the Atacama soil development.

The geochemical, isotopic and mineralogical composition of atmospheric dust deposited along a West-East transect in …

The Formation Of Distal Impact Ejecta, Brandon C. Johnson

Open Access Dissertations

Here we present two models for the dynamics of ejection and formation of distal impact ejecta. The first model focuses on the most highly shocked material that forms a massive expanding vapor plume or fireball. In this model molten droplets or spherules condense from the vapor. We model the expanding vapor plume using a one dimensional Lagrangian hydrocode. The condensation of droplets is treated by directly coupling the equations for homogeneous nucleation and growth with our hydrocode. The second model is focused on less energetic material ejected as part of the excavation flow. Using the iSALE hydrocode, we determine the …

Observation-Based Algorithm Development For Subsurface Hydrology In Northern Temperate Wetlands, Chun-Mei Chiu

Open Access Dissertations

This study investigates wetland subsurface hydrology, as well as biogeochemistry - which is strongly influenced by water and temperature dynamics - as these interactions are expected to be highly significant, yet remain poorly represented in current ecosystem and climate models.

Northern wetlands have received widespread public attention due to steadily increasing summer mean global temperatures, extreme precipitation events and higher rates of natural greenhouse gas emissions, as well as the significant impacts on them due to human activities. The goal of my graduate research has been to improve quantification of the role of subsurface hydrology in northern wetlands by using …