Conference Papers
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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse almost 5,000 conference papers authored by our scientists and refine search by topic, location, year, and advanced search.
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Evaluating the effect of Tikhonov regularization schemes on predictions in a variable-density groundwater model Evaluating the effect of Tikhonov regularization schemes on predictions in a variable-density groundwater model
Calibration of highly‐parameterized numerical models typically requires explicit Tikhonovtype regularization to stabilize the inversion process. This regularization can take the form of a preferred parameter values scheme or preferred relations between parameters, such as the preferred equality scheme. The resulting parameter distributions calibrate the model to a user‐defined acceptable...
Authors
Jeremy T. White, Christian D. Langevin, Joseph D. Hughes
Use of time series and harmonic constituents of tidal propagation to enhance estimation of coastal aquifer heterogeneity Use of time series and harmonic constituents of tidal propagation to enhance estimation of coastal aquifer heterogeneity
A synthetic two‐dimensional model of a horizontally and vertically heterogeneous confined coastal aquifer system, based on the Upper Floridan aquifer in south Florida, USA, subjected to constant recharge and a complex tidal signal was used to generate 15‐minute water‐level data at select locations over a 7‐day simulation period. “Observed” water‐level data were generated by adding noise
Authors
Joseph D. Hughes, Jeremy T. White, Christian D. Langevin
Assessing societal vulnerability of U.S. Pacific Northwest communities to storm-induced coastal change Assessing societal vulnerability of U.S. Pacific Northwest communities to storm-induced coastal change
Progressive increases in storm intensities and extreme wave heights have been documented along the U.S. West Coast. Paired with global sea level rise and the potential for an increase in El Niño occurrences, these trends have substantial implications for the vulnerability of coastal communities to natural coastal hazards. Community vulnerability to hazards is characterized by the...
Authors
Heather M. Baron, Nathan J. Wood, Peter Ruggerio, Jonathan Allan, Patrick Corcoran
Climate change, cranes, and temperate floodplain ecosystems Climate change, cranes, and temperate floodplain ecosystems
Floodplain ecosystems provide important habitat to cranes globally. Lateral, longitudinal, vertical, and temporal hydrologic connectivity in rivers is essential to maintaining the functions and values of these systems. Agricultural development, flood control, water diversions, dams, and other anthropogenic activities have greatly affected hydrologic connectivity of river systems...
Authors
Sammy L. King
A geochemical module for "AMDTreat" to compute caustic quantity, effluent quantity, and sludge volume A geochemical module for "AMDTreat" to compute caustic quantity, effluent quantity, and sludge volume
Treatment with caustic chemicals typically is used to increase pH and decrease concentrations of dissolved aluminum, iron, and/or manganese in largevolume, metal-laden discharges from active coal mines. Generally, aluminum and iron can be removed effectively at near-neutral pH (6 to 8), whereas active manganese removal requires treatment to alkaline pH (~10). The treatment cost depends...
Authors
Charles A. Cravotta, David L. Parkhurst, Brent P Means, Bob McKenzie, Harry Morris, Bill Arthur
Modeling the dynamic geochemistry of prairie pothole wetlands Modeling the dynamic geochemistry of prairie pothole wetlands
No abstract available.
Authors
M.C. Goldhaber, C.T. Mills, Craig A. Stricker, J. W. LaBaugh, D. Mushet, N.H. Euliss
Comparison of turbidity to multi-frequency sideways-looking acoustic-Doppler data and suspended-sediment data in the Colorado River in Grand Canyon Comparison of turbidity to multi-frequency sideways-looking acoustic-Doppler data and suspended-sediment data in the Colorado River in Grand Canyon
Water clarity is important to biologists when studying fish and other fluvial fauna and flora. Turbidity is an indicator of the cloudiness of water, or reduced water clarity, and is commonly measured using nephelometric sensors that record the scattering and absorption of light by particles in the water. Unfortunately, nephelometric sensors only operate over a narrow range of the...
Authors
Nicholas Voichick, David J. Topping
The upper crust on its side---Steeply tilted slabs in the basin and range The upper crust on its side---Steeply tilted slabs in the basin and range
No abstract available.
Authors
Keith A. Howard
Evaluation of the role of magmatic volatiles from Eocene mafic to felsic igneous rocks in the formation of Carlin-type gold deposits of the Carlin trend and Jerritt Canyon District as constrained by preliminary He, Pb, Sr, and Nd isotopic data Evaluation of the role of magmatic volatiles from Eocene mafic to felsic igneous rocks in the formation of Carlin-type gold deposits of the Carlin trend and Jerritt Canyon District as constrained by preliminary He, Pb, Sr, and Nd isotopic data
No abstract available.
Authors
Albert H. Hofstra, Gary P. Landis, Wayne R. Premo, M.W. Ressel, Christopher D. Henry
Paleozoic stratigraphy and kinematics of the Roberts Mountains allochthon in the Independence Mountains, northern Nevada Paleozoic stratigraphy and kinematics of the Roberts Mountains allochthon in the Independence Mountains, northern Nevada
New biostratigraphic, stratigraphic, and structural data from deformed lower Paleozoic sedimentary units of the Roberts Mountains allochthon (RMA), Independence Mountains, Nevada, have enabled the identification of stratigraphic units within the allochthon that range in age from Late Cambrian through Late Devonian. The McAfee thrust fault emplaced a relatively thick (>200 m) sheet of...
Authors
Christopher S. Holm-Denoma, Albert H. Hofstra, Stephen A. Leslie, Paula J. Noble
'Forensic' geochemical approaches to constrain the source of Au-Ag in low-sulfidation epithermal ores 'Forensic' geochemical approaches to constrain the source of Au-Ag in low-sulfidation epithermal ores
In order to better constrain genetic processes involved in forming mineral deposits (and ultimately exploration models), it helps to know from where the metals of interest are derived. How the metals arrived at their point of deposition, and why they were deposited there, are separate issues. We are using three different techniques in an attempt to better understand these processes for...
Authors
James A. Saunders, G. D. Kamenov, Albert H. Hofstra, D. L. Unger, R. A. Creaser, F. Barra
Petrology and hydrothermal alteration of Jurassic intrusive rocks associated with gold deposits in the Bald Mountain mining district, White Pine County, Nevada Petrology and hydrothermal alteration of Jurassic intrusive rocks associated with gold deposits in the Bald Mountain mining district, White Pine County, Nevada
No abstract available.
Authors
Edward A. du Bray, J. Thomas Nash, Gregory P. Meeker, David Adams, William A. Wright