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Articles 1 - 10 of 10
Full-Text Articles in Earth Sciences
Numerical Modeling Of The Effects Of Land Use Change And Irrigation On Streamflow Depletion Of Frenchman Creek, Nebraska, Moussa Guira
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 …
Investigating Mechanisms Of Hydraulic Conductivity Transience In Sandy Streambeds, Wilhelm Fraundorfer
Investigating Mechanisms Of Hydraulic Conductivity Transience In Sandy Streambeds, Wilhelm Fraundorfer
School of Natural Resources: Dissertations, Theses, and Student Research
Streambed hydraulic conductivity (K) is known to be spatially and temporally heterogeneous, but few attempts to understand the controls on temporal variability have been made. This study documents temporal K transience and demonstrates how hydraulic, geophysical, and sedimentological methods can be combined to understand the processes that give rise to changes in streambed K. Falling head permeameter tests and slug tests were conducted to determine vertical K (Kv) and K (slug test K), respectively. These tests were repeated three times over a twelve-week period on the same grid at a depth of 0.5 …
Combining Hydraulic Head Analysis With Airborne Electromagnetics To Detect And Map Impermeable Aquifer Boundaries, Jesse T. Korus
Combining Hydraulic Head Analysis With Airborne Electromagnetics To Detect And Map Impermeable Aquifer Boundaries, Jesse T. Korus
Conservation and Survey Division
Impermeable aquifer boundaries affect the flow of groundwater, transport of contaminants, and the drawdown of water levels in response to pumping. Hydraulic methods can detect the presence of such boundaries, but these methods are not suited for mapping complex, 3D geological bodies. Airborne electromagnetic (AEM) methods produce 3D geophysical images of the subsurface at depths relevant to most groundwater investigations. Interpreting a geophysical model requires supporting information, and hydraulic heads offer the most direct means of assessing the hydrostratigraphic function of interpreted geological units. This paper presents three examples of combined hydraulic and AEM analysis of impermeable boundaries in glacial …
Three-Dimensional Architecture And Hydrostratigraphy Of Cross-Cutting Buried Valleys Using Airborne Electromagnetics, Glaciated Central Lowlands, Nebraska, Usa, Jesse T. Korus Dr., Robert Matthew Joeckel, Dana P. Divine, Jared D. Abraham
Three-Dimensional Architecture And Hydrostratigraphy Of Cross-Cutting Buried Valleys Using Airborne Electromagnetics, Glaciated Central Lowlands, Nebraska, Usa, Jesse T. Korus Dr., Robert Matthew Joeckel, Dana P. Divine, Jared D. Abraham
Conservation and Survey Division
Buried valleys are characteristic features of glaciated landscapes, and their deposits host important aquifers worldwide. Understanding the stratigraphic architecture of these deposits is essential for protecting groundwater and interpreting sedimentary processes in subglacial and ice-marginal environments. The relationships between depositional architecture, topography and hydrostratigraphy in dissected, pre-Illinoian till sheets is poorly understood. Boreholes alone are inadequate to characterize the complex geology of buried valleys, but airborne electromagnetic surveys have proven useful for this purpose. A key question is whether the sedimentary architecture of buried valleys can be interpreted from airborne electromagnetic profiles. This study employs airborne electromagnetic resistivity profiles to …
Potential Aquifer Vulnerability In Regions Down-Gradient From Uranium In Situ Recovery (Isr) Sites, James A. Saunders, Bruce E. Pivetz, Nathan Voorhies, Richard T. Wilkin
Potential Aquifer Vulnerability In Regions Down-Gradient From Uranium In Situ Recovery (Isr) Sites, James A. Saunders, Bruce E. Pivetz, Nathan Voorhies, Richard T. Wilkin
United States Environmental Protection Agency: Staff Publications
Sandstone-hosted roll-front uranium ore deposits originate when U(VI) dissolved in groundwater is reduced and precipitated as insoluble U(IV) minerals. Groundwater redox geochemistry, aqueous complexation, and solute migration are important in leaching uranium from source rocks and transporting it in low concentrations to a chemical redox interface where it is deposited in an ore zone typically containing the uranium minerals uraninite, pitchblende, and/or coffinite; various iron sulfides; native selenium; clays; and calcite. In situ recovery (ISR) of uranium ores is a process of contacting the uranium mineral deposit with leaching and oxidizing (lixiviant) fluids via injection of the lixiviant into wells …
Comment On ‘‘An Unconfined Groundwater Model Of The Death Valley Regional Flow System And A Comparison To Its Confined Predecessor’’ By R.W.H. Carroll, G.M. Pohll And R.L. Hershey [Journal Of Hydrology 373/3–4, Pp. 316–328], Claudia C. Faunt, Alden M. Provost, Mary C. Hill, Wayne R. Belcher
Comment On ‘‘An Unconfined Groundwater Model Of The Death Valley Regional Flow System And A Comparison To Its Confined Predecessor’’ By R.W.H. Carroll, G.M. Pohll And R.L. Hershey [Journal Of Hydrology 373/3–4, Pp. 316–328], Claudia C. Faunt, Alden M. Provost, Mary C. Hill, Wayne R. Belcher
United States Geological Survey: Staff Publications
Carroll et al. (2009) state that the United States Geological Survey (USGS) Death Valley Regional Flow System (DVRFS) model, which is based on MODFLOW, is ‘‘conceptually inaccurate in that it models an unconfined aquifer as a confined system and does not simulate unconfined drawdown in transient pumping simulations.’’ Carroll et al. (2009) claim that ‘‘more realistic estimates of water availability’’ can be produced by a SURFACT-based model of the DVRFS that simulates unconfined groundwater flow and limits withdrawals from wells to avoid excessive drawdown. Differences in results from the original MODFLOW- based model and the SURFACT-based model stem primarily from …
Investigation Of Spatial And Temporal Processes Of Lake-Aquifer Interactions In The Nebraska Sand Hills, John T. Ong
Investigation Of Spatial And Temporal Processes Of Lake-Aquifer Interactions In The Nebraska Sand Hills, John T. Ong
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Interaction between surface water and groundwater is an important component of the water cycle that affects the physicochemical and biological characteristics of lakes, streams, wetlands, and seacoasts. Due to the complex interaction of geologic, topographic, and hydrologic factors, flow between lakes and groundwater remains poorly understood. Evolution of conceptual models over the past 30 years describes processes of advection, dispersion, and free convection that occur in different lake flow regimes. Few detailed field studies document the validity of these conceptual models because of the difficulty of studying the subsurface and the prohibitive cost of instrumenting large areas. In the semi-arid …
Biogeochemical Behavior Of Dissolved Arsenic And Uranium Concentrations In Public Water Supply Wells, Kevin J. Mcvey
Biogeochemical Behavior Of Dissolved Arsenic And Uranium Concentrations In Public Water Supply Wells, Kevin J. Mcvey
School of Natural Resources: Dissertations, Theses, and Student Research
Public water supply (PWS) wells currently contain dissolved uranium concentrations above the federally mandated maximum contaminant level (MCL) of 30 ppb (parts per billion) and dissolved arsenic concentrations above the 10 ppb MCL. Both uranium and arsenic are known to cause various forms of cancer in humans. Variations in total uranium concentrations in PWS wells in Nebraska indicate a relationship to the duration and rate of pumping in specific wells. Although total arsenic concentrations show some variability over time in specific wells, the relationship to pumping is not as clear. Previous studies show that iron and sulfur bacteria present in …
G93-1191 Glossary Of Water-Related Terms, William L. Kranz, Delynn Hay, James W. Goeke, David Gosselin
G93-1191 Glossary Of Water-Related Terms, William L. Kranz, Delynn Hay, James W. Goeke, David Gosselin
University of Nebraska-Lincoln Extension: Historical Materials
This NebGuide is a glossary of water quantity, quality and human health related terms involving water. Terms are defined in contexts that could affect Nebraskans. We depend upon water for our very existence. The impact of water quality and quantity issues has never been greater. Yet the terminology used to describe the water we drink, the water we provide to plants and animals, the water stored underground, in lakes, rivers, and oceans, is not well understood by many Nebraskans. This listing of water-related terms is intended to reduce the potential for misunderstanding presentations made by elected officials, environmental agencies and …
Hydrogeology Of Garfield And Wheeler Counties, Nebraska, Dennis R. Lawton, Robert A. Hiergesell
Hydrogeology Of Garfield And Wheeler Counties, Nebraska, Dennis R. Lawton, Robert A. Hiergesell
Conservation and Survey Division
No abstract provided.