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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 more than 65,000 articles authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Using ensemble data assimilation to estimate transient hydrologic exchange flow under highly dynamic flow conditions Using ensemble data assimilation to estimate transient hydrologic exchange flow under highly dynamic flow conditions
Quantifying dynamic hydrologic exchange flows (HEFs) within river corridors that experience high-frequency flow variations caused by dam regulations is important for understanding the biogeochemical processes at the river water and groundwater interfaces. Heat has been widely used as a tracer to infer steady-state flow velocities through analytical solutions of heat transport defined by...
Authors
K. C. Chen, Xingyuan Chen, X. Song, Martin A. Briggs, P. Jiang, P. Shuai, G. Hammond, H. Zhang, J. Zachara
Bolide impact effects on the West Florida Platform, Gulf of Mexico: End Cretaceous and late Eocene Bolide impact effects on the West Florida Platform, Gulf of Mexico: End Cretaceous and late Eocene
This study documents seismic reflection evidence that two different bolide impacts significantly disrupted stratigraphic and depositional processes on the West Florida Platform. The first impact terminated the Late Cretaceous Epoch (Chicxulub; ~66 Ma; end Maastrichtian age). The second took place in the late Eocene (Chesapeake Bay; ~35 Ma; Priabonian age). Both impacts produced far...
Authors
Claude (Wylie) Poag
A climate-mediated shift in the estuarine habitat mosaic limits prey availability and reduces nursery quality for juvenile salmon A climate-mediated shift in the estuarine habitat mosaic limits prey availability and reduces nursery quality for juvenile salmon
The estuarine habitat mosaic supports the reproduction, growth, and survival of resident and migratory fish species by providing a diverse portfolio of unique habitats with varying physical and biological features. Global climate change is expected to result in increasing temperatures, rising sea levels, and changes in riverine hydrology, which will have profound effects on the extent...
Authors
Melanie J. Davis, Isa Woo, Christopher S. Ellings, Sayre Hodgson, David Beauchamp, Glynnis Nakai, Susan E.W. De La Cruz
Urban landcover differentially drives day and nighttime air temperature across a semi-arid city Urban landcover differentially drives day and nighttime air temperature across a semi-arid city
Semi-arid urban environments are undergoing an increase in both average air temperatures and in the frequency and intensity of extreme heat events. Within cities, different composition and densities of urban landcovers (ULC) influence local air temperatures, either mitigating or increasing heat. Currently, understanding how combinations of ULC influence air temperature at the block to...
Authors
Peter Christian Ibsen, G. Darrel Jenerette, Tyler Dell, Kenneth J. Bagstad, James E. Diffendorfer
GW/SW-MST: A groundwater/surface-water method selection tool GW/SW-MST: A groundwater/surface-water method selection tool
Groundwater/surface-water (GW/SW) exchange and hyporheic processes are topics receiving increasing attention from the hydrologic community. Hydraulic, chemical, temperature, geophysical, and remote sensing methods are used to achieve various goals (e.g., inference of GW/SW exchange, mapping of bed materials, etc.), but the application of these methods is constrained by site conditions...
Authors
Steven Hammett, Frederick Day-Lewis, Brett Russell Trottier, Paul M. Barlow, Martin A. Briggs, Geoffrey N. Delin, Judson Harvey, Carole D. Johnson, John W. Lane, D.O. Rosenberry, Dale D. Werkema
Large fires or small fires, will they differ in affecting shifts in species composition and distributions under climate change? Large fires or small fires, will they differ in affecting shifts in species composition and distributions under climate change?
Climate change is expected to increase fire activity, which has the potential to accelerate climate-induced shifts in species composition and distribution in the boreal-temperate ecotone. Wildfire can kill resident trees, and thus provide establishment opportunities for migrating tree species. However, the role of fire size and its interactions with tree species with varied life-history...
Authors
Wenru Xu, Hong S. He, Chao Huang, Shengwu Duan, Todd Hawbaker, Paul D. Henne, Yu Liang, Zhiliang Zhu
A review of the microtremor horizontal-to-vertical spectral ratio (MHVSR) method A review of the microtremor horizontal-to-vertical spectral ratio (MHVSR) method
The single-station microtremor horizontal-to-vertical spectral ratio (MHVSR) method was initially proposed to retrieve the site amplification function and its resonance frequencies produced by unconsolidated sediments overlying high-velocity bedrock. Presently, MHVSR measurements are predominantly conducted to obtain an estimate of the fundamental site frequency at sites where a strong...
Authors
S. Molnar, A. Sirohey, J. Assaf, P.-Y. Bard, C. Castellaro, C. Cornou, B. Cox, B. Guillier, B. Hassani, H. Kawase, S. Matsushima, F. J. Sánchez-Sesma, Alan Yong
A review of near-surface QS estimation methods using active and passive sources A review of near-surface QS estimation methods using active and passive sources
Seismic attenuation and the associated quality factor (Q) have long been studied in various sub-disciplines of seismology, ranging from observational and engineering seismology to near-surface geophysics and soil/rock dynamics with particular emphasis on geotechnical earthquake engineering and engineering seismology. Within the broader framework of seismic site characterization, various
Authors
Stefano Parolai, Carlo G. Lai, Ilaria Dreossi, Olga-Joan Ktenidou, Alan K. Yong
Modeling the dynamics of salt marsh development in coastal land reclamation Modeling the dynamics of salt marsh development in coastal land reclamation
The valuable ecosystem services of salt marshes are spurring marsh restoration projects around the world. However, it is difficult to determine the final vegetated area based on physical drivers. Herein, we use a 3D fully coupled vegetation-hydrodynamic-morphological modeling system (COAWST), to simulate the final vegetation cover and the timescale to reach it under various forcing...
Authors
Yiyang Xu, Tarandeep S. Kalra, Neil K. Ganju, Sergio Fagherazzi
Average kinship within bighorn sheep populations is associated with connectivity, augmentation, and bottlenecks Average kinship within bighorn sheep populations is associated with connectivity, augmentation, and bottlenecks
Understanding the influence of population attributes on genetic diversity is important to advancement of biological conservation. Because bighorn sheep (Ovis canadensis) populations vary in size and management history, the species provides a unique opportunity to observe the response of average pairwise kinship, inversely related to genetic diversity, to a spectrum of natural and...
Authors
Elizabeth P Flesch, Tabitha A. Graves, Jennifer Thomson, Kelly M. Proffitt, Robert A. Garrott
Influence of offshore oil and gas structures on seascape ecological connectivity Influence of offshore oil and gas structures on seascape ecological connectivity
Offshore platforms, subsea pipelines, wells and related fixed structures supporting the oil and gas (O&G) industry are prevalent in oceans across the globe, with many approaching the end of their operational life and requiring decommissioning. Although structures can possess high ecological diversity and productivity, information on how they interact with broader ecological processes...
Authors
Dianne L McLean, Luciana C. Ferreira, Jessica A Benthuysen, Karen J. Miller, Marie-Lise Schlappy, Matthew J. Ajemian, Oliver Berry, Silvana N. R. Birchenough, Todd Bond, Fabio Boschetti, Ann S Bull, Jeremy T Claisse, Scott A Condie, Pierpaolo Consoli, Joop W. P. Coolen, Michael R. Elliott, Irene S Fortune, Ashley M Fowler, Bronwyn M Gillanders, Hugo B Harrison, Kristen Hart, Lea-Anne Henry, Chad L Hewitt, Natalie Hicks, Karlo Hock, Kieran Hyder, Milton S. Love, Peter I Macreadie, Robert J. Miller, William A Montevecchi, Mary M Nishimoto, Henry M. Page, David M Paterson, Charitha B Pattiaratchi, Gretta T Pecl, Joanne S Porter, David B. Reeves, Cynthia Riginos, Sally Rouse, Debbie J. F. Russell, Craig D. H. Sherman, Jonas Teilmann, Victoria L. G. Todd, Eric A. Treml, David H. Williamson, Michele Thums
Coupling validation effort with in situ bioacoustic data improves estimating relative activity and occupancy for multiple species with cross-species misclassifications Coupling validation effort with in situ bioacoustic data improves estimating relative activity and occupancy for multiple species with cross-species misclassifications
The increasing complexity and pace of ecological change requires natural resource managers to consider entire species assemblages. Acoustic recording units (ARUs) require minimal cost and effort to deploy and inform relative activity, or encounter rates, for multiple species simultaneously. ARU-based surveys require post-processing of the recordings via software algorithms that assign a...
Authors
Christian Stratton, Kathryn M. Irvine, Katharine M. Banner, Wilson J. Wright, Cori Lausen, Jason Rae