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Full-Text Articles in Earth Sciences

Estimating Dominant Runoff Modes Across The Conterminous United States, Brian Buchanan, Daniel A. Auerbach, James Knighton, Darrick Evensen, Daniel R. Fuka, Zachary Easton, Michael Wieczorek, Josephine A. Archibald, Brandon Mcwilliams, Todd Walter Sep 2018

Estimating Dominant Runoff Modes Across The Conterminous United States, Brian Buchanan, Daniel A. Auerbach, James Knighton, Darrick Evensen, Daniel R. Fuka, Zachary Easton, Michael Wieczorek, Josephine A. Archibald, Brandon Mcwilliams, Todd Walter

United States Geological Survey: Staff Publications

Effective natural resource planning depends on understanding the prevalence of runoff generating processes. Within a specific area of interest, this demands reproducible, straightforward information that can complement available local data and can orient and guide stakeholders with diverse training and backgrounds. To address this demand within the contiguous United States (CONUS), we characterized and mapped the predominance of two primary runoff generating processes: infiltration‐excess and saturation‐excess runoff (IE vs. SE, respectively). Specifically, we constructed a gap‐filled grid of surficial saturated hydraulic conductivity using the Soil Survey Geographic and State Soil Geographic soils databases. We then compared surficial saturated hydraulic conductivity …


Using Cumulative Potential Recharge For Selection Of Gcm Projections To Force Regional Groundwater Models: A Nebraska Sand Hills Example, Nathan R. Rossman, Vitaly A. Zlotnik, Clinton Rowe Sep 2018

Using Cumulative Potential Recharge For Selection Of Gcm Projections To Force Regional Groundwater Models: A Nebraska Sand Hills Example, Nathan R. Rossman, Vitaly A. Zlotnik, Clinton Rowe

Department of Earth and Atmospheric Sciences: Faculty Publications

Groundwater recharge (GR) controls vegetation, geomorphology, groundwater, wetlands and surface flow, and ultimately, the ecology and economics of semi-arid regions. Therefore, it is critical to assess hydroclimate model scenarios and the uncertainty in future GR to force regional groundwater models. We use basic statistics of downscaled Global Circulation Model (GCM)-projected cumulative potential GR (GRp) for selecting representative projections. Cumulative GRp is the net recharge (difference between precipitation (P) and evapotranspiration (ET) rates) over the projection period. The approach is illustrated with an example in the Nebraska Sand Hills (NSH), the largest dune …


Report Of Community Conversations About Gender Roles In Livestock, Mamusha Lemma, Wole Kinati, Annet Mulema, Zekarias Bassa, Abiro Tigabe, Hiwot Desta, Mesfin Mekonnen, Tadious Asfaw Sep 2018

Report Of Community Conversations About Gender Roles In Livestock, Mamusha Lemma, Wole Kinati, Annet Mulema, Zekarias Bassa, Abiro Tigabe, Hiwot Desta, Mesfin Mekonnen, Tadious Asfaw

Daugherty Water for Food Global Institute: Faculty Publications

The International Livestock Research Institute (ILRI) and the International Center for Research in the Dry Areas (ICARDA) gender and animal health teams facilitated community conversations (CCs) about gender roles in livestock husbandry in three districts in the Southern Nations, Nationalities and Peoples Region (SNNPR) and Amhara region from 30 May–07 June 2018. These dictricts were: Doyogena (Hawora Arara and Ancha Sadicha kebeles) of SNNPR from 30 and 31 May; and Menz Gera district (Sine Amba kebele) and Menz Mama district (Key Afer kebele) of Amhara from June 6–7. In Doyogena, the team held the conversations in farmer training centres (FTCs) …


Umphlett Qci Sept 2018, Natalie Umphlett Sep 2018

Umphlett Qci Sept 2018, Natalie Umphlett

High Plains Regional Climate Center: Staff Publications

Highlights for the Basin

Temperature and Precipitation Anomalies

Drought

Water Resources

Agriculture

Temperature

Precipitation


County-Wide Assessment Of Irrigation Expansion On Air Temperature, Humidity And Evapotranspiration Rates In Nebraska, 1979-2015, Jozsef Szilagyi Sep 2018

County-Wide Assessment Of Irrigation Expansion On Air Temperature, Humidity And Evapotranspiration Rates In Nebraska, 1979-2015, Jozsef Szilagyi

Conservation and Survey Division: Faculty and Staff Publications

Total irrigated land area has been expanding in Nebraska over the last 40 years, propelling the state into a leading position within the US in terms of irrigated acreages. Typically, those counties which display the largest degree of irrigation development had a significant portion of their land area already irrigated in 1978. Large-scale irrigation in Nebraska affects its atmospheric environment. During the typical irrigation season of May to August, counties with the largest rate of irrigation expansion have cooled by about 0.2 – 0.3 °F per decade in the summer months of June, July and August, while counties with the …


Global Dynamics Of A Mutualism–Competition Model With One Resource And Multiple Consumers, Yuanshi Wang, Hong Wu, Donald L. Deangelis Aug 2018

Global Dynamics Of A Mutualism–Competition Model With One Resource And Multiple Consumers, Yuanshi Wang, Hong Wu, Donald L. Deangelis

United States Geological Survey: Staff Publications

Recent simulation modeling has shown that species can coevolve toward clusters of coexisting consumers exploiting the same limiting resource or resources, with nearly identical ratios of coefficients related to growth and mortality. This paper provides a mathematical basis for such as situation; a full analysis of the global dynamics of a new model for such a class of n-dimensional consumer–resource system, in which a set of consumers with identical growth to mortality ratios compete for the same resource and in which each consumer is mutualistic with the resource. First, we study the system of one resource and two consumers. …


Ancient Convergent Losses Of Paraoxonase 1 Yield Potential Risks For Modern Marine Mammals, Wynn K. Meyer, Jerrica Jamison, Rebecca Richter, Stacy E. Woods, Raghavendran Partha, Amanda Kowalczyk, Charles Kronk, Maria Chikina, Robert K. Bonde, Daniel E. Crocker, Joseph Gaspard, Janet M. Lanyon, Judit Marsillach, Clement E. Furlong, Nathan L. Clark Aug 2018

Ancient Convergent Losses Of Paraoxonase 1 Yield Potential Risks For Modern Marine Mammals, Wynn K. Meyer, Jerrica Jamison, Rebecca Richter, Stacy E. Woods, Raghavendran Partha, Amanda Kowalczyk, Charles Kronk, Maria Chikina, Robert K. Bonde, Daniel E. Crocker, Joseph Gaspard, Janet M. Lanyon, Judit Marsillach, Clement E. Furlong, Nathan L. Clark

United States Geological Survey: Staff Publications

Mammals diversified by colonizing drastically different environments, with each transition yielding numerous molecular changes, including losses of protein function. Though not initially deleterious, these losses could subsequently carry deleterious pleiotropic consequences. We have used phylogenetic methods to identify convergent functional losses across independent marine mammal lineages. In one extreme case, Paraoxonase 1 (PON1) accrued lesions in all marine lineages, while remaining intact in all terrestrial mammals. These lesions coincide with PON1 enzymatic activity loss in marine species’ blood plasma. This convergent loss is likely explained by parallel shifts in marine ancestors’ lipid metabolism and/or bloodstream oxidative environment affecting PON1’s role …


Internal Parasites Of The Two Subspecies Of The West Indian Manatee Trichechus Manatus, Heidi Wyrosdick, Alycia Chapman, Antonio A. Mignucci-Giannoni, Carla I. Rivera-Pérez, Robert K. Bonde Aug 2018

Internal Parasites Of The Two Subspecies Of The West Indian Manatee Trichechus Manatus, Heidi Wyrosdick, Alycia Chapman, Antonio A. Mignucci-Giannoni, Carla I. Rivera-Pérez, Robert K. Bonde

United States Geological Survey: Staff Publications

The West Indian manatee Trichechus manatus is divided into 2 subspecies: the Antillean (T. m. manatus) and Florida (T. m. latirostris) manatees. This study reports sample prevalence of manatee parasites from populations of these 2 subspecies in different geographical locations. Although necropsy is a valuable diagnostic tool for parasite infections, the need for antemortem diagnostic techniques is important. Fecal samples collected during necropsies of Antillean manatees (n = 3) in Puerto Rico and Florida manatees (n = 10) in Crystal River, Florida, as well as from live-captured Florida manatees (n = 11) were evaluated using centrifugal …


Serum Proteins In Healthy And Diseased Florida Manatees (Trichechus Manatus Latirostris), J.W. Harvey, K.E. Harr, D. Murphy, M.T. Walsh, M. De Wit, R.K. Bonde Aug 2018

Serum Proteins In Healthy And Diseased Florida Manatees (Trichechus Manatus Latirostris), J.W. Harvey, K.E. Harr, D. Murphy, M.T. Walsh, M. De Wit, R.K. Bonde

United States Geological Survey: Staff Publications

A major goal of this study was to determine whether serum protein fractions of healthy Florida manatees differ with age, sex, or living environments (wild versus housed). A second goal was to determine which serum protein fractions vary in diseased versus healthy manatees. Serum protein fractions were determined using agarose gel electrophoresis. Healthy adults had slightly higher total serum protein and total globulin concentrations than younger animals. This largely resulted from an increase in gamma globulins with age. Total serum protein, albumin, alpha-1 globulin, beta globulin, and total globulin concentrations were slightly higher in housed manatees compared to wild manatees, …


Boundary Spanners And Trust Development Between Stakeholders In Integrated Water Resource Management: A Mixed Methods Study, Jodi L. Delozier Aug 2018

Boundary Spanners And Trust Development Between Stakeholders In Integrated Water Resource Management: A Mixed Methods Study, Jodi L. Delozier

School of Natural Resources: Dissertations, Theses, and Student Research

Natural resource issues are inherently complex, even more so are those that involve the management of water. Because watersheds tend to cross multiple jurisdictional and geographical boundaries, a diverse set of stakeholders are needed to develop appropriate and sustainable management policy. This research sheds light on the importance of boundary spanners assisting in the development of trust between stakeholders in integrated water resource management (IWRM). Previous literature has explored the advantages to boundary spanning leadership in business practice, emergency management, university and community management as well as fish and wildlife management, but has failed to address the area of integrated …


Distribution And Habitat Association Of The Northern Long-Eared Bat, Zachary A. Warren Aug 2018

Distribution And Habitat Association Of The Northern Long-Eared Bat, Zachary A. Warren

School of Natural Resources: Dissertations, Theses, and Student Research

Because of white-nose syndrome, the northern long-eared bat (Myotis septentrionalis) is experiencing rapid population declines across the majority of its range. This decline has prompted increased regulatory protection and thus an increased need for effective habitat management strategies. Insight into the species habitat associations, however, is a prior necessity to ensure management practices are biologically relevant. Understanding these relationships requires a holistic approach that addresses the multiple ways in which the species is interacting with its environment. The objective of my thesis was to address these relationships following a multi-scale approach that assessed the factors associated with roost …


A Comparison Of Vnir And Mir Spectroscopy For Predicting Various Soil Properties, Joshua R. Gates Aug 2018

A Comparison Of Vnir And Mir Spectroscopy For Predicting Various Soil Properties, Joshua R. Gates

School of Natural Resources: Dissertations, Theses, and Student Research

Soil plays an important role in our daily lives, namely producing food, cleaning water and storing carbon. The ability to rapidly and cost-effectively quantify the various components of soils can help us understand and better manage this important resource. This study aims to compare the ability of visible near-infrared (VNIR) spectroscopy and mid-infrared (MIR) spectroscopy to quickly and accurately predict various important soil properties (electrical conductivity, soil pH, cation exchange capacity, exchangeable cations, phosphorus, carbon, beta-glucosidase enzyme activity and nitrogen). Prediction models were developed using partial least squares regression (PLSR) techniques. Three different calibration sampling methods were tested along with …


A Quantitative Analysis Of Calcareous Nannofossils Across A Late Oligocene Paleolatitude Transect Of The North Atlantic Ocean, William Barrett Clark Aug 2018

A Quantitative Analysis Of Calcareous Nannofossils Across A Late Oligocene Paleolatitude Transect Of The North Atlantic Ocean, William Barrett Clark

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Samples from ODP Sites 926, 628, 563, U1406, 647, and 918, were analyzed quantitatively across a paleolatitude transect of the North Atlantic Ocean to determine the paleolatitudinal distribution of calcareous nannofossils in the Late Oligocene and the effects of that distribution on biostratigraphic resolution. Detrended Correspondence Analysis (DCA), a Temperature index (TI), and the Shannon Diversity Index (H), were used to examine the paleoenvironmental gradients which exerted the most control over the distribution of species and their abundances. The temperature index correlates significantly to the first axis of the DCA, suggesting that thermal controls were the most important factor in …


Relationships Between Landscape Constraints And A Crayfish Assemblage With Consideration Of Competitor Presence, Joshua B. Mouser, Robert Mollenhauer, Shannon K. Brewer Jul 2018

Relationships Between Landscape Constraints And A Crayfish Assemblage With Consideration Of Competitor Presence, Joshua B. Mouser, Robert Mollenhauer, Shannon K. Brewer

United States Geological Survey: Staff Publications

Aim: Crayfish are globally diverse and one of the most important taxa in North American streams. Despite their importance, many species are of conservation concern and efforts to improve conditions are limited. Here, we address two major impediments to improving conditions: (a) our lack of knowledge of the interplay among natural landscape and human-induced changes; and (b) a very limited understanding of how species interactions affect overall crayfish distributions.

Location: Ozark Highlands ecoregion, USA.

Methods: We used both existing data and field-collected data to examine the relationships between 12 Faxonius species and physicochemical variables at multiple spatial scales. Data were …


Quantifying The Distribution And Mechanisms Accommodating Penetrative Strain Along The Western Margin Of The Laramide Denver–Julesburg Basin, Marques Hatfield Jul 2018

Quantifying The Distribution And Mechanisms Accommodating Penetrative Strain Along The Western Margin Of The Laramide Denver–Julesburg Basin, Marques Hatfield

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Grain-scale volume loss is an important process in the deformation of a fold-thrust belt. Prior to activation of slip on fault surfaces, and initiation of layer buckling in folds, instability is recorded by thickening of parallel bedding surfaces, grain boundary migration, and stress-induced solution transfer of mineral grains. Volume loss recorded by these mechanisms is significant but is an afterthought in any type of cross-section restoration.

This research has three main objectives. Firstly, to estimate the amount of penetrative strain (PS) accommodated in weakly deformed sandstones along four E-W transects, from the thick-skinned Colorado Front Range into the Denver-Julesburg Basin. …


Estimating Adaptation To Climate Change In Groundwater Irrigation, James Keeler Jul 2018

Estimating Adaptation To Climate Change In Groundwater Irrigation, James Keeler

Department of Agricultural Economics: Dissertations, Theses, and Student Research

Understanding the adaptive capacity of irrigated agriculture, including to what extent producers adjust irrigation choices along the intensive and extensive margins, is vital to the development of accurate and holistic estimates of the impacts of climate change on agricultural production and the sustainability of water-related ecosystem services. This thesis proposes and implements a natural experiment using statistical matching methods to estimate how producers adjust groundwater extraction, irrigated crop acreage, and irrigation technology in response to long-term changes in precipitation and evapotranspiration. Results from groundwater irrigated fields in Kansas suggest that intensive and extensive margin water use adaptations are generally limited …


Groundwater Discharge Characteristics For Selected Streams Within The Loup River Basin, Nebraska, 2014–16, Christopher M. Hobza, Aaron R. Schepers Jul 2018

Groundwater Discharge Characteristics For Selected Streams Within The Loup River Basin, Nebraska, 2014–16, Christopher M. Hobza, Aaron R. Schepers

United States Geological Survey: Water Reports and Publications

Streams in the Loup River Basin are sensitive to groundwater withdrawals because of the close hydrologic connection between groundwater and surface water. Groundwater discharge is the primary component of streamflow in the Loup River Basin and constitutes more than 90 percent of streamflow in the central part of the Sand Hills. To improve the understanding of geologic controls and various climatic and land-use changes on groundwater discharge, the United States Geological Survey (USGS), in cooperation with the Upper Loup Natural Resources District (NRD), the Lower Loup NRD, and the Nebraska Environmental Trust, studied the spatial and temporal characteristics of groundwater …


The Global Food-Energy-Water Nexus, Paolo D’Odorico, Kyle Frankel Davis, Lorenzo Rosa, Joel A. Carr, Davide Chiarelli, Jampel Dell’Angelo, Jessica Gephart, Graham K. Macdonald, David A. Seekell, Samir Suweis, Maria Cristina Rulli Jul 2018

The Global Food-Energy-Water Nexus, Paolo D’Odorico, Kyle Frankel Davis, Lorenzo Rosa, Joel A. Carr, Davide Chiarelli, Jampel Dell’Angelo, Jessica Gephart, Graham K. Macdonald, David A. Seekell, Samir Suweis, Maria Cristina Rulli

United States Geological Survey: Staff Publications

Abstract Water availability is a major factor constraining humanity’s ability to meet the future food and energy needs of a growing and increasingly affluent human population. Water plays an important role in the production of energy, including renewable energy sources and the extraction of unconventional fossil fuels that are expected to become important players in future energy security. The emergent competition for water between the food and energy systems is increasingly recognized in the concept of the “food-energy-water nexus.” The nexus between food and water is made even more complex by the globalization of agriculture and rapid growth in food …


Including Farmer Irrigation Behavior In A Sociohydrological Modeling Framework With Application In North India, Jimmy O’Keeffe, Simon Moulds, Emma Bergin, Nick Brozovic, Ana Mijic, Wouter Buytaert Jul 2018

Including Farmer Irrigation Behavior In A Sociohydrological Modeling Framework With Application In North India, Jimmy O’Keeffe, Simon Moulds, Emma Bergin, Nick Brozovic, Ana Mijic, Wouter Buytaert

Daugherty Water for Food Global Institute: Faculty Publications

Understanding water user behavior and its potential outcomes is important for the development of suitable water resource management options. Computational models are commonly used to assist water resource management decision making; however, while natural processes are increasingly well modeled, the inclusion of human behavior has lagged behind. Improved representation of irrigation water user behavior within models can provide more accurate and relevant information for irrigation management in the agricultural sector. This paper outlines a model that conceptualizes and proceduralizes observed farmer irrigation practices, highlighting impacts and interactions between the environment and behavior. It is developed using a bottom-up approach, informed …


The Effects Of Continuous Diazinon Exposure On Growth And Reproduction In Japanese Medaka Using A Modified Medaka Extended One Generation Reproduction Test (Meogrt), Kevin Flynn, Doug Lothenbach, Frank Whiteman, Dean Hammermeister, Joe Swintek, Matthew Etterson, Rodney Johnson Jul 2018

The Effects Of Continuous Diazinon Exposure On Growth And Reproduction In Japanese Medaka Using A Modified Medaka Extended One Generation Reproduction Test (Meogrt), Kevin Flynn, Doug Lothenbach, Frank Whiteman, Dean Hammermeister, Joe Swintek, Matthew Etterson, Rodney Johnson

United States Environmental Protection Agency: Publications

The Medaka Extended One Generation Reproduction Test (MEOGRT) is a Tier 2 test within U.S. Environmental Protection Agency's (USEPA) Endocrine Disruptor Screening Program (EDSP), designed to characterize the potential adverse effects to fish of exposure to chemical that can cause disruption of the endocrine system. The MEOGRT focuses primarily on adverse effects to reproduction while collecting information regarding effects on growth, survival, and endocrine-related endpoints. However, the risk assessment process for fish, as mandated by legislation such as the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) or the Toxic Substances Control Act (TSCA), could benefit from a more detailed assessment …


Variation In Home Range Size And Patterns In Adult Female American Crocodiles Crocodylus Acutus, Jeffrey S. Beauchamp, Kristen M. Hart, Michael S. Cherkiss, Frank J. Mazzotti Jul 2018

Variation In Home Range Size And Patterns In Adult Female American Crocodiles Crocodylus Acutus, Jeffrey S. Beauchamp, Kristen M. Hart, Michael S. Cherkiss, Frank J. Mazzotti

United States Geological Survey: Staff Publications

The American crocodile Crocodylus acutus is a threatened species that uses relatively deep, open-water habitats with low salinity. Adult female American crocodiles nest on sandy coastal beaches, islands or human-made berms, assist in the hatching process, and can travel long distances to nesting habitat. We satellite-tracked 15 adult female American crocodiles in 2 hydrologically distinct areas in Everglades National Park, Florida, USA, to quantify the home range sizes, test for intraspecific differences in home range and core area size and structure, and identify important crocodile high-use areas. Overall home ranges (95% kernel density estimate; KDE) for adult female crocodiles in …


Coupling Toxicokinetic–Toxicodynamic And Population Models For Assessing Aquatic Ecological Risks To Time-Varying Pesticide Exposures, Glen Thursby, Keith Sappington, Matthew Etterson Jul 2018

Coupling Toxicokinetic–Toxicodynamic And Population Models For Assessing Aquatic Ecological Risks To Time-Varying Pesticide Exposures, Glen Thursby, Keith Sappington, Matthew Etterson

United States Environmental Protection Agency: Publications

Population modeling evaluations of pesticide exposure time series were compared with aspects of a currently used risk assessment process. The US Environmental Protection Agency’s Office of Pesticide Programs models daily aquatic 30-yr pesticide exposure distributions in its risk assessments, but does not routinely make full use of the information in such time series.We used mysid shrimp Americamysis bahia toxicity and demographic data to demonstrate the value of a toxicokinetic– toxicodynamic model coupled with a series of matrix population models in risk assessment refinements. This species is a small epibenthic marine crustacean routinely used in regulatory toxicity tests. We demonstrate how …


Correction To: Organochlorine Chemical Residues In Northern Cardinal (Cardinalis Cardinalis) Eggs From Greater Washington, Dc Usa, Christopher J. Schmitt, Kathy R. Echols, Paul H. Peterman, Carl E. Orazio, K. Christiana Grim, Shirlee Tan, Nora E. Diggs, Peter P. Marra Jul 2018

Correction To: Organochlorine Chemical Residues In Northern Cardinal (Cardinalis Cardinalis) Eggs From Greater Washington, Dc Usa, Christopher J. Schmitt, Kathy R. Echols, Paul H. Peterman, Carl E. Orazio, K. Christiana Grim, Shirlee Tan, Nora E. Diggs, Peter P. Marra

United States Geological Survey: Staff Publications

The original version of this article contained a mistake. Author name in the text citation and reference in section should be Maldonado et al (2016), it was incorrectly spelled as Maldinado et al (2015).


The Prairie Post Quarterly Newsletter Of The High Plains Regional Climate Center- July 2018, Natalie Umphlett, Emily Brown, Crystal J. Stiles Jul 2018

The Prairie Post Quarterly Newsletter Of The High Plains Regional Climate Center- July 2018, Natalie Umphlett, Emily Brown, Crystal J. Stiles

Prairie Post: Quarterly Newsletter of the High Plains Regional Climate Center

Inside this issue:

Message from the interim director........................................1

Staff spotlight...........................1

GRAINEX project......................2

Product highlights..................3

Update on regional climate conditions..................................4

GIS Portal....................................4

Regional news..........................5

Recent and upcoming travel and activities.............................6


Droughtscape, Summer 2018, National Drought Mitigation Center Jul 2018

Droughtscape, Summer 2018, National Drought Mitigation Center

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

Contents

From the director

Drought expands and intensifies

Dry down fuels fires

Tweeting #drought18

MOISST and NSMN

Caribbean planning progress

Drought observer network study

MENA teams report progress

NDMC global outreach

Climate hub workshop

On the horizon


Isotopic And Geochemical Analysis Of Nitrate Contaminated Groundwater In Edgar, Nebraska, Nathan Roddy Jul 2018

Isotopic And Geochemical Analysis Of Nitrate Contaminated Groundwater In Edgar, Nebraska, Nathan Roddy

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

High nitrate concentrations in the groundwater beneath Edgar, Nebraska have been measured for well over a decade, exceeding the EPA’s MCL of 10 mg-N/L. Investigating the isotopic signature of nitrate and groundwater have determined the likely source(s) of contamination. Apparent seasonal changes exists in nitrate concentration, isotope ratios, and geochemistry, suggesting that sources and flow paths change as a result of irrigation. Samples collected in December and May had very similar nitrate concentrations (average value of 13.7 mg-N/L) and isotopic ratios (δ15N 4.46‰ and δ18O-NO3 20.21‰), suggesting synthetic nitrate fertilizers are the major source of …


Integrated Geophysical Analysis In The Northeastern Gulf Of Mexico, Mei Liu Jul 2018

Integrated Geophysical Analysis In The Northeastern Gulf Of Mexico, Mei Liu

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The formation of the Gulf of Mexico (GoM) relates to the breakup of Pangea and opening of the central Atlantic Ocean. The tectonic history of the basin is still being debated due to lack of geological constraints. This project addresses the crustal architecture in the northeastern GoM from integrative analysis of multiple geophysical datasets to provide constraints for the tectonic reconstruction.

The objectives of this study are: 1) to delineate various tectonic zones (continental and oceanic domains) and map the boundary between them, 2) to derive physical properties of the subsurface rocks, 3) to map the major tectonic structures in …


Assessment Of The Ponderosa Woodlands In Nebraska's Wildcat Hills: Implications For Juniperus Encroachment And Management, Allie Victoria Schiltmeyer Jul 2018

Assessment Of The Ponderosa Woodlands In Nebraska's Wildcat Hills: Implications For Juniperus Encroachment And Management, Allie Victoria Schiltmeyer

School of Natural Resources: Dissertations, Theses, and Student Research

Ponderosa pine (Pinus ponderosa) is a dominant tree species across western North America. Its eastern distribution includes three populations in western Nebraska. This study assesses the distribution, structure and age of ponderosa pine woodlands in one of those regions, the Wildcat Hills. The Wildcat Hills have escaped severe wildfires seen in recent decades in other ponderosa pine regions. Nevertheless, the Wildcat Hills woodlands face multiple threats including climate change, wildfire, drought, pine beetles, and invasive species. Key to these threats is the stand structure of pine woodlands, which have increased in density across much of ponderosa pine’s range. …


Analysis Of Gravity Recovery And Climate Experiment (Grace) Satellite-Derived Data As A Groundwater And Drought Monitoring Tool, Anthony James Mucia Jul 2018

Analysis Of Gravity Recovery And Climate Experiment (Grace) Satellite-Derived Data As A Groundwater And Drought Monitoring Tool, Anthony James Mucia

School of Natural Resources: Dissertations, Theses, and Student Research

This research compares Gravity Recovery and Climate Experiment (GRACE) groundwater storage (GWS) and root zone soil moisture (RZSM) percentiles to measured data, other drought indicators (DIs) and indices, and stakeholder observations for the purpose of assessing the feasibility and usefulness of these products to detect drought conditions. GRACE percentiles were directly compared to historic groundwater percentiles at 89 Nebraska well locations. Spatial time-series correlations over CONUS were performed between GRACE GWS and RZSM and the U.S. Drought Monitor (USDM), Standardized Precipitation Index (SPI), and soil moisture parameters from several North American Land Data Assimilation System (NLDAS) models. A survey of …


Numerical Modeling Of The Effects Of Land Use Change And Irrigation On Streamflow Depletion Of Frenchman Creek, Nebraska, Moussa Guira Jul 2018

Numerical Modeling Of The Effects Of Land Use Change And Irrigation On Streamflow Depletion Of Frenchman Creek, Nebraska, Moussa Guira

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

A three-dimensional Control Volume Finite Difference-based numerical groundwater flow model was constructed to assess the effects of agricultural irrigation and land use change on streamflow depletion. The study area is Frenchman Creek basin located in southwestern corner of the State of Nebraska, USA. This area was subject to an increased proliferation of groundwater abstraction for agricultural purposes since industrial revolution. It has also been subject to land use change from native rangeland to dry and irrigated cropland. The groundwater flow model was spatially discretized using Voronoi cells in unstructured grid built with the USGS MODFLOW-6. Temporal discretization defined 151 time …