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2016

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Articles 361 - 390 of 511

Full-Text Articles in Geology

Oceans And Shorelines, John J. Renton, Thomas Repine Jan 2016

Oceans And Shorelines, John J. Renton, Thomas Repine

Readings and Notes

Until 1872 when H.M.S, Challenger, a British warship converted for research, made its historic voyage, relatively little was known about the oceans. The voyage, funded by the British government, was mandated to chart the depth of the ocean, measure the various ocean currents, amass data on the composition of the ocean's water and bottom sediments, and collect information on ocean life. At the time of the voyage, except for a few soundings, almost nothing was known about the ocean bottom. Most scientists of the day had considered the vast expanses of the deep ocean basins to be nothing more than …


Comparison Of The Elemental Geochemistry Of The Arkansas Novaculite And The Boone Chert In Their Type Regions, Arkansas, J. Philbrick, E. Pollock, A. Potra Jan 2016

Comparison Of The Elemental Geochemistry Of The Arkansas Novaculite And The Boone Chert In Their Type Regions, Arkansas, J. Philbrick, E. Pollock, A. Potra

Journal of the Arkansas Academy of Science

The name Arkansas Novaculite was proposed by A.H. Purdue, 1909 to replace the name Arkansas Stone assigned by L. S. Griswold, 1892, but deemed too generic, to an interval of Early Devonian-Early Mississippian, very fine-grained, even textured, siliceous sedimentary rock famous for use as whetstones. The interval is exposed along the margins of the Benton Uplift, south flank of the Ouachita Mountains, west-central Arkansas, where it reaches a maximum thickness of 243.8 m (800 ft). The Arkansas Novaculite comprises informal lower and upper members characterized by massive beds of nearly pure novaculite, separated by a shale-bearing middle member that spans …


Recent Increases In Arctic Freshwater Flux Affects Labrador Sea Convection And Atlantic Overturning Circulation, Qian Yang, Tim Dixon, Paul G. Myers, Jennifer Bonin, Don Chambers, M.R. Van Den Broeke, Mads H. Ribergaard, John Mortensen Jan 2016

Recent Increases In Arctic Freshwater Flux Affects Labrador Sea Convection And Atlantic Overturning Circulation, Qian Yang, Tim Dixon, Paul G. Myers, Jennifer Bonin, Don Chambers, M.R. Van Den Broeke, Mads H. Ribergaard, John Mortensen

School of Geosciences Faculty and Staff Publications

The Atlantic Meridional Overturning Circulation (AMOC) is an important component of ocean thermohaline circulation. Melting of Greenland’s ice sheet is freshening the North Atlantic; however, whether the augmented freshwater flux is disrupting the AMOC is unclear. Dense Labrador Sea Water (LSW), formed by winter cooling of saline North Atlantic water and subsequent convection, is a key component of the deep southward return flow of the AMOC. Although LSW formation recently decreased, it also reached historically high values in the mid-1990s, making the connection to the freshwater flux unclear. Here we derive a new estimate of the recent freshwater flux from …


Juvenile Survival And Adult Return As A Function Of Freshwater Rearing Life History For Coho Salmon In The Klamath River Basin, Molly Gorman Jan 2016

Juvenile Survival And Adult Return As A Function Of Freshwater Rearing Life History For Coho Salmon In The Klamath River Basin, Molly Gorman

Cal Poly Humboldt theses and projects

The Scott and Shasta rivers, Klamath River tributaries, experience spatial disparity in habitat quality in spring and summer as a result of historical and current land-use. Juvenile Coho Salmon (Oncorhynchus kisutch) born in the upper tributary reaches often rear in natal streams before migrating to sea. However, those born in the lower reaches often encounter unsuitable habitat and emigrate during their first spring to seek non-natal rearing habitats. It is assumed that these early outmigrants are population losses. This study evaluated first-summer survival, and contribution to the adult population, of non-natal rearing juveniles in the Klamath River Basin. …


Hazardready – A Geographically Based Natural Hazard Education And Preparedness Web Application, Carson C. Macpherson-Krutsky Ms. Jan 2016

Hazardready – A Geographically Based Natural Hazard Education And Preparedness Web Application, Carson C. Macpherson-Krutsky Ms.

Graduate Student Theses, Dissertations, & Professional Papers

Earthquakes, floods, wildfires, and other natural disasters are inevitable and costly both in terms of lives lost and money spent on recovery. Scientific research on natural hazards is widely shared within the scientific community, but is less often made more widely accessible, as methods or pathways for providing scientific natural hazard information and data in non-technical language are limited. Priorities for imparting hazard information include: 1) scientific accuracy, 2) spatial granularity, 3) integration of information about all relevant hazards, 4) nontechnical content, 5) appropriate preparedness activities, and 6) engagement with existing disaster response and mitigation capabilities. In response to these …


Storing Co2 Deep Underground, Stephen F. Greb Jan 2016

Storing Co2 Deep Underground, Stephen F. Greb

Map and Chart--KGS

No abstract provided.


Injecting Liquids And Gases Deep Underground, Stephen F. Greb Jan 2016

Injecting Liquids And Gases Deep Underground, Stephen F. Greb

Map and Chart--KGS

Every year, thousands of wells are drilled into underground reservoirs in search of water, oil, and natural gas. The gases and fluids are trapped inside tiny pores and cracks in underground reservoirs.


Rocks To Roads To Ruin: A Brief History Of Western Kentucky’S Rock-Asphalt Industry, 1888–1957, J. Richard Bowersox Jan 2016

Rocks To Roads To Ruin: A Brief History Of Western Kentucky’S Rock-Asphalt Industry, 1888–1957, J. Richard Bowersox

Information Circular--KGS

The history of western Kentucky’s rock-asphalt industry required substantial research of primary sources to correct the disjointed and often conflicting record published to date. Its history is checkered with characters from visionary entrepreneurs and ambitious businessmen to financial scoundrels. The earliest evidence of exploitation of bitumen resources at the surface in western Kentucky is in Native American artifacts recovered from several sites. Early settlers in the region used heavy oil and bitumen found in seeps as lubricants and wood preservatives, among other uses. The commercial value of the widespread western Kentucky rock-asphalt deposits was first recognized in the 1880’s, leading …


Mapped Karst Groundwater Basins In The Elizabethtown 30 X 60 Minute Quadrangle, James C. Currens, Robert J. Blair Jan 2016

Mapped Karst Groundwater Basins In The Elizabethtown 30 X 60 Minute Quadrangle, James C. Currens, Robert J. Blair

Map and Chart--KGS

This map shows karst groundwater basins in the Elizabethtown 30 x 60 minute quadrangle, determined primarily by groundwater tracer studies. It can be used to quickly identify the groundwater basins and springs to which a site may drain. Major springs and the relative size of their catchment areas can be evaluated for potential as water supplies. The map also serves as a geographic index to literature on karst groundwater in the area.


Heavy-Oil And Bitumen Resources Of The Western Kentucky Tar Sands, J. Richard Bowersox Jan 2016

Heavy-Oil And Bitumen Resources Of The Western Kentucky Tar Sands, J. Richard Bowersox

Report of Investigations--KGS

Heavy-oil and bitumen resources in western Kentucky are present in the Upper Mississippian Big Clifty and Hardinsburg Sandstones and Lower Pennsylvanian Kyrock and Bee Spring Sandstone Members of the Caseyville Formation in a belt extending from Logan County on the south to Breckinridge and Hardin Counties on the north.

Net oil-saturated intervals in the tar sands range from 2.5 to 4.7 m thick, largely in downthrown fault blocks in and bounding the Rough Creek Graben. Records from 1,500 wells, analysis of reservoir properties from 3,769 plugs from 135 coreholes, and bulk volume of hydrocarbon calculated in 139 surface samples were …


Petrography, Mineralogy, And Geochemistry Of Greenish- And Reddish-Gray Siltstones Straddling The Vertebrate-Defined Permian–Triassic Boundary In South Africa, Jiawen Li Jan 2016

Petrography, Mineralogy, And Geochemistry Of Greenish- And Reddish-Gray Siltstones Straddling The Vertebrate-Defined Permian–Triassic Boundary In South Africa, Jiawen Li

Honors Theses

The Permian–Triassic Mass Extinction (PTME) is considered the largest in Earth’s history, yet the terrestrial response is not well understood. The Karoo Basin, South Africa, hosts abundant exposures of terrestrial deposits that span the Permian– Triassic Boundary (PTB). The terrestrial PTB is defined by a turnover in vertebrate assemblage zones and has been associated with a transition from greenish-gray to reddish-gray siltstone. The current PTME model states that the siltstone color change is a reflection of aridification and eolian deposition, which is believed to represent rapid climate change directly linked with the event. Greenish- and reddish-gray siltstones were collected from …


Documenting Mantle And Crustal Contributions To Flood Basalt Magmatism Via Computational Modeling Of The Steens Basalt, Southeast Oregon, Sylvana J. Bendaña Jan 2016

Documenting Mantle And Crustal Contributions To Flood Basalt Magmatism Via Computational Modeling Of The Steens Basalt, Southeast Oregon, Sylvana J. Bendaña

All Master's Theses

Flood basalts are enormous volcanic events with volumes of volcanic cover and intrusive equivalents that are affected by and significantly affect the crust. Steens Basalt represents 31,800 km3 of flood basalt lavas that erupted in eastern Oregon ~16.8 Ma in less than 300,000 years. Analytical data of flows from a 1 km vertical exposure at Steens Mtn. documents time-transgressive changes in composition of two geochemically distinct units: (1) lower Steens, MgO-rich lavas with lower incompatible trace element concentrations and 87Sr/86Sr, and (2) upper Steens, MgO-poor, with higher incompatible trace element concentrations and 87Sr/86Sr. …


Deserts And Wind, John J. Renton, Thomas Repine Jan 2016

Deserts And Wind, John J. Renton, Thomas Repine

Readings and Notes

About one third of Earth's land surface is either arid (< 10" ppt./yr or semi-arid (10" to 20" pt./yr). While most precipitation is in the form of rain, some may be provided by melting snow, mist, or fog. With limited availability of water, rocks are not subjected to chemical weathering but rather to physical weathering.


Igneous Rocks, John J. Renton, Thomas Repine Jan 2016

Igneous Rocks, John J. Renton, Thomas Repine

Readings and Notes

No abstract provided.


Modeling Bedrock Transmissivity; Implications For Contaminant Transport In An Overlying Glacial Aquifer System, Amanda Pruehs Jan 2016

Modeling Bedrock Transmissivity; Implications For Contaminant Transport In An Overlying Glacial Aquifer System, Amanda Pruehs

Wayne State University Theses

This study evaluated alternative representations of bedrock surface and bedrock transmissivity on advective transport predictions in an 11 km x 15 km x 116 m groundwater model. Bedrock topography, initially based on a map by Kunkle (1961), was reinterpreted using data from 227 additional bedrock penetrations drilled in the last 55 years. Varying assumptions of hydraulic conductivity were employed to model a range of bedrock conductivity from 1 to 3 orders of magnitude less than the overlying glacial aquifer system. MODPATH forward particle tracking and MT3DMS advective-dispersive transport modeling were employed to explore the influence of bedrock configuration and conductivity …


Use And Evaluation Of Lidar For Mapping Sinkholes In Royal Spring Groundwater Basin, Fidele Nsonguh Tibouo Jan 2016

Use And Evaluation Of Lidar For Mapping Sinkholes In Royal Spring Groundwater Basin, Fidele Nsonguh Tibouo

Theses and Dissertations--Earth and Environmental Sciences

This study utilizes a digital elevation model of the surface derived from high-resolution LiDAR (Light Detection and Ranging) and aerial-image technologies to map sinkholes in the Royal Spring groundwater basin. Shade-relief maps, with vertical exaggeration, were very helpful in the initial characterization of depressions. Then, aerial-photography sets were likewise helpful in identifying man-made structures such as retention basins, swimming pools, and parking lots, and to identify new sinkholes.

Field checking was necessary to further define depressions into two categories: 1.) potential sinkholes and 2.) probable sinkholes. This study had a lower success rate (50 percent) for identifying sinkholes via LiDAR …


Effects Of Folding On Mineral Cpos In Gneiss: Implications For Lower Crustal Seismic Anisotropy, Alexia K. Sarnowsky Jan 2016

Effects Of Folding On Mineral Cpos In Gneiss: Implications For Lower Crustal Seismic Anisotropy, Alexia K. Sarnowsky

Wayne State University Theses

Isotropic seismic properties are not sufficient to distinguish between many rock types believed to make up the middle and lower continental crust. Seismic anisotropy is the directional dependence of seismic velocity, which we can use to improve our understanding of the composition and structure of the middle and lower continental crust. Our rationale is that seismic anisotropy in the middle and lower crust is controlled by the crystallographic preferred orientation (CPO) of minerals. The effects of folding on mineral CPO in a folded gneiss from the Coweeta Group in North Carolina is used for this study, and we should be …


Developing Priority Variables (“Ecosystem Essential Ocean Variables” — Eeovs) For Observing Dynamics And Change In Southern Ocean Ecosystems, Andrew J. Constable, Daniel P. Costa, Oscar Schofield, Louise Newman, Edward R. Urban Jr., Elizabeth A. Fulton, Jessica Melbourne-Thomas, Tosca Ballerini, Philip W. Boyd, Angelika Brandt, Eileen E. Hofmann Jan 2016

Developing Priority Variables (“Ecosystem Essential Ocean Variables” — Eeovs) For Observing Dynamics And Change In Southern Ocean Ecosystems, Andrew J. Constable, Daniel P. Costa, Oscar Schofield, Louise Newman, Edward R. Urban Jr., Elizabeth A. Fulton, Jessica Melbourne-Thomas, Tosca Ballerini, Philip W. Boyd, Angelika Brandt, Eileen E. Hofmann

CCPO Publications

Reliable statements about variability and change in marine ecosystems and their underlying causes are needed to report on their status and to guide management. Here we use the Framework on Ocean Observing (FOO) to begin developing ecosystem Essential Ocean Variables (eEOVs) for the Southern Ocean Observing System (SOOS). An eEOV is a defined biological or ecological quantity, which is derived from field observations, and which contributes significantly to assessments of Southern Ocean ecosystems. Here, assessments are concerned with estimating status and trends in ecosystem properties, attribution of trends to causes, and predicting future trajectories. eEOVs should be feasible to collect …


A Small-Scale Water Budget Approach And Water Quality Assessment: A Case Study For Calderas Lake, Guatemala, Edrick Ramos Jan 2016

A Small-Scale Water Budget Approach And Water Quality Assessment: A Case Study For Calderas Lake, Guatemala, Edrick Ramos

Dissertations, Master's Theses and Master's Reports

Increases in water demand and urban development in Calderas community over the past decade have led to questions about the hydrology, water quality, quantity and sustainable management of Calderas Lake micro-basin. However, studies on baseline hydrology are limited for rural communities located inside volcanic origin watersheds of Guatemala. The scope of this study was to characterize the hydrology and establish a method to: 1) quantify a water budget, and 2) qualify the water quality of a lacustrine system that supply water for about 17,000 inhabitants on the state limits or rural Guatemala City. Mean annual rainfall and temperature at the …


Sea Lamprey Mating Pheromone Registered By U.S. Environmental Protection Agency As First Vertebrate Pheromone Biopesticide, Marc Gaden, Marisa Lubeck Jan 2016

Sea Lamprey Mating Pheromone Registered By U.S. Environmental Protection Agency As First Vertebrate Pheromone Biopesticide, Marc Gaden, Marisa Lubeck

United States Geological Survey: Publications

Ann Arbor, MI – The U.S. Environmental Protection Agency registered a sea lamprey mating pheromone, 3kPZS, as the first ever vertebrate pheromone biopesticide in late December, 2015. Like an alluring perfume, the mating pheromone is a scent released by male sea lampreys to lure females onto nesting sites. Research and development of the mating pheromone was funded by the Great Lakes Fishery Commission, with additional support from the Great Lakes Restoration Initiative, in collaboration with federal government, university, and private industry partners.


Gross And Microscopic Lesions In Corals From Micronesia, T. M. Work, G. S. Aeby, K. A. Hughen Jan 2016

Gross And Microscopic Lesions In Corals From Micronesia, T. M. Work, G. S. Aeby, K. A. Hughen

United States Geological Survey: Staff Publications

The authors documented gross and microscopic morphology of lesions in corals on 7 islands spanning western, southern, and eastern Micronesia, sampling 76 colonies comprising 30 species of corals among 18 genera, with Acropora, Porites, and Montipora dominating. Tissue loss comprised the majority of gross lesions sampled (41%), followed by discoloration (30%) and growth anomaly (29%). Of 31 cases of tissue loss, most lesions were subacute (48%), followed by acute and chronic (26% each). Of 23 samples with discoloration, most were dark discoloration (40%), with bleaching and other discoloration each constituting 30%. Of 22 growth anomalies, umbonate growth anomalies composed …


Bioaccessibility Tests Accurately Estimate Bioavailability Of Lead To Quail, W. Nelson Beyer, Nicholas T. Basta, Rufus L. Chaney, Paula F.P. Henry, David E. Mosby, Barnett A. Rattner, Kirk G. Scheckel, Daniel T. Sprague, John S. Weber Jan 2016

Bioaccessibility Tests Accurately Estimate Bioavailability Of Lead To Quail, W. Nelson Beyer, Nicholas T. Basta, Rufus L. Chaney, Paula F.P. Henry, David E. Mosby, Barnett A. Rattner, Kirk G. Scheckel, Daniel T. Sprague, John S. Weber

United States Geological Survey: Staff Publications

Hazards of soil-borne lead (Pb) to wild birds may be more accurately quantified if the bioavailability of that Pb is known. To better understand the bioavailability of Pb to birds, the authors measured blood Pb concentrations in Japanese quail (Coturnix japonica) fed diets containing Pb-contaminated soils. Relative bioavailabilities were expressed by comparison with blood Pb concentrations in quail fed a Pb acetate reference diet. Diets containing soil from 5 Pb-contaminated Superfund sites had relative bioavailabilities from 33% to 63%, with a mean of approximately 50%. Treatment of 2 of the soils with phosphorus (P) significantly reduced the bioavailability …


A Personal Perspective On Searching For The Ivory-Billed Woodpecker: A 41-Year Quest, Paul W. Sykes Jr. Jan 2016

A Personal Perspective On Searching For The Ivory-Billed Woodpecker: A 41-Year Quest, Paul W. Sykes Jr.

United States Geological Survey: Staff Publications

I first learned about the Patuxent Wildlife Research Center (Patuxent) in Laurel, MD, while attending high school in the mid-1950s. Patuxent wildlife biologists Brooke Meanley, Chandler (Chan) S. Robbins, and Robert (Bob) E. Stewart, Sr., visited me at my parents’ home in Norfolk, VA. I was the compiler of the Norfolk County Christmas Bird Count (which included the eastern portion of the Virginia sector of the Dismal Swamp). As part of that count, we had for several years been estimating populations of red-winged blackbirds (Agelaius phoeniceus) and common grackles (Quiscalus quiscula) in the millions. Patuxent was …


Patuxent’S Role In The Development Of The North American Breeding Bird Survey, John R. Sauer Jan 2016

Patuxent’S Role In The Development Of The North American Breeding Bird Survey, John R. Sauer

United States Geological Survey: Staff Publications

The North American Breeding Bird Survey (BBS) is a roadside survey of the breeding birds of North America. The BBS provides data from the contiguous United States, Alaska, southern and central Canada, and northern Mexico. Begun in 1966 by Chandler (Chan) S. Robbins at the U.S. Geological Survey (USGS) Patuxent Wildlife Research Center (Patuxent), and now jointly managed by Patuxent, the Canadian Wildlife Service, and the Mexican Commission for the Knowledge and Use of Biodiversity, the survey is conducted primarily in June along more than 5,000 roadside survey routes that are surveyed once each year. Volunteer observers drive the 39.4-kilometer …


Patuxent’S Long-Term Research On Wolves, David L. Mech Jan 2016

Patuxent’S Long-Term Research On Wolves, David L. Mech

United States Geological Survey: Staff Publications

The gray wolf (Canis lupus) was one of the first species placed on the Endangered Species List in 1967. The Endangered Species Act of 1973 legally protected the wolf along with other listed species. Patuxent Wildlife Research Center (Patuxent) in Laurel, MD, began its Endangered Wildlife Program in 1966, and U.S. Fish and Wildlife Service (USFWS) biologist Ray Erickson was assigned to lead it. In 1973, I was transferred to the program from Region 3 of the USFWS, having been employed there since 1969 to study wolves in Minnesota. Endangered Species Act protection of the wolf fostered its …


A Spatio-Temporal Comparison Of Avian Migration Phenology Using Citizen Science Data, Ali Arab, Jason R. Courter, Jessica Zelt Jan 2016

A Spatio-Temporal Comparison Of Avian Migration Phenology Using Citizen Science Data, Ali Arab, Jason R. Courter, Jessica Zelt

United States Geological Survey: Staff Publications

The effects of climate change have wide-ranging impacts on wildlife species and recent studies indicate that birds’ spring arrival dates are advancing in response to changes in global climates. In this paper, we propose a spatio-temporal approach for comparing avian first arrival data for multiple species. As an example, we analyze spring arrival data for two long-distance migrants (Rubythroated Hummingbird Archilochus colubris; and Purple Martin Progne subis) in eastern North America from 2001–2010 using Citizen Science data. The proposed approach provides researchers with a tool to compare mean arrival dates while accounting for spatial and temporal variability. Our results show …


Phosphorus Retention In A Lowland Neotropical Stream Following An Eight-Year Enrichment Experiment, Gaston E. Small, Marcelo Ardón, John H. Duff, Alan P. Jackman, Alonso Ramírez, Frank J. Triska, Catherine M. Pringle Jan 2016

Phosphorus Retention In A Lowland Neotropical Stream Following An Eight-Year Enrichment Experiment, Gaston E. Small, Marcelo Ardón, John H. Duff, Alan P. Jackman, Alonso Ramírez, Frank J. Triska, Catherine M. Pringle

United States Geological Survey: Staff Publications

Human alteration of the global P cycle has led to widespread P loading in freshwater ecosystems. Much research has been devoted to the capacity of wetlands and lakes to serve as long-term sinks for P inputs from the watershed, but we know much less about the potential of headwater streams to serve in this role. We assessed storage and retention of P in biotic and abiotic compartments after an 8-y experimental P addition to a 1st-order stream in a Neotropical wet forest. Sediment P extractions indicated that nearly all P storage was in the form of Fe- and Al-bound P …


Cyclostratigraphy And Sedimentation Of The Cenomanian-Turonian Tuscaloosa Marine Shale, Christian Gilbert Kunhardt Jan 2016

Cyclostratigraphy And Sedimentation Of The Cenomanian-Turonian Tuscaloosa Marine Shale, Christian Gilbert Kunhardt

Electronic Theses and Dissertations

A cyclostratigraphic and geochemical analysis was conducted on the basal high resistivity zone of the Tuscaloosa Marine Shale to determine if orbital forcing is apparent in mineralogical data suites. Geochemical data suites obtained via x-ray diffraction from five cored wells located near the southern Mississippi/Louisiana border were used in the study. The results were used in concert with previously published insolation and biostratigraphic data and unpublished stable carbon isotope data to determine sedimentation rate, to identify and correlate the cretaceous oceanic anoxic event 2 (OAE 2) recovery period within the studied interval, and to determine the possible mechanisms of orbital …


Portable X-Ray Fluorescence Measurement Viability In Organic Rich Soils: Pxrf Response As A Function Of Organic Matter Presence, Roozbeh Ravansari Jan 2016

Portable X-Ray Fluorescence Measurement Viability In Organic Rich Soils: Pxrf Response As A Function Of Organic Matter Presence, Roozbeh Ravansari

Wayne State University Theses

Portable X-Ray fluorescence provides a cost effective method for producing rapid geochemical data. With advancements in X-Ray generation and detection technology, pXRF has become feasible for use on pedologic materials. Factors affecting pXRF soil measurements such as heterogeneity, moisture content, object geometry, and matrix interferences are widely recognized. However, the influence of organic matter on pXRF soil measurements is poorly understood.

This study examined the influence of organic matter fraction on pXRF trace metal measurements in a soil matrix. Incremental addition of three organic matter surrogates (cellulose, graphite powder, and confectioner’s sugar) was used to investigate the influence of increasing …


Integration Of Deterministic And Stochastic Models In A 1,4-Dioxane Contaminated Glacial Aquifer System, Washtenaw County, Michigan, Lena Kristin Pappas Jan 2016

Integration Of Deterministic And Stochastic Models In A 1,4-Dioxane Contaminated Glacial Aquifer System, Washtenaw County, Michigan, Lena Kristin Pappas

Wayne State University Theses

Hybrid models incorporating stochastic variability within a deterministic hydrostratigraphic framework provide an effective way to assess uncertainty in flow and transport model predictions. This study evaluated the distribution of groundwater flow and contaminant transport pathways in two ensembles of spatially variable hydraulic conductivity (K) distributions. The models comprised a 360 ft-thick sequence of Pleistocene glacial sediments in in an approximately 8 mi2 area across Washtenaw County, Michigan. Conditioned K fields were generated using Sequential Gaussian Simulation (SGS) and Sequential Indicator Simulation (SIS) constructed using indicator classes based on natural gamma ray logs from 77 monitoring wells. K fields were modeled …