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Browse more than 82,000 reports 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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South Fork Shenandoah River habitat-flow modeling to determine ecological and recreational characteristics during low-flow periods South Fork Shenandoah River habitat-flow modeling to determine ecological and recreational characteristics during low-flow periods

The ecological habitat requirements of aquatic organisms and recreational streamflow requirements of the South Fork Shenandoah River were investigated by the U.S. Geological Survey in cooperation with the Central Shenandoah Valley Planning District Commission, the Northern Shenandoah Valley Regional Commission, and Virginia Commonwealth University. Physical habitat simulation modeling...
Authors
Jennifer L. Krstolic, R. Clay Ramey

Southern and Central California Chaparral and Oak Woodlands Ecoregion: Chapter 19 in Status and trends of land change in the Western United States--1973 to 2000 Southern and Central California Chaparral and Oak Woodlands Ecoregion: Chapter 19 in Status and trends of land change in the Western United States--1973 to 2000

The Southern and Central California Chaparral and Oak Woodlands Ecoregion, which covers approximately 102,110 km2 (39,425 mi2), is characterized by a Mediterranean climate with cool, moist winters and hot, dry summers (Omernik, 1987; U.S. Environmental Protection Agency, 1997). Natural vegetation includes chaparral (for example, manzanita, Arctostaphylos spp.) and oak (Quercus spp.)...
Authors
Darrell E. Napton

Southern California Mountains Ecoregion: Chapter 18 in Status and trends of land change in the Western United States--1973 to 2000 Southern California Mountains Ecoregion: Chapter 18 in Status and trends of land change in the Western United States--1973 to 2000

This chapter has been modified from original material published in Soulard and others (2007), entitled “Land-cover trends of the Southern California Mountains ecoregion” (U.S. Geological Survey Scientific Investigations Report 2007–5235). The Southern California Mountains Ecoregion (Omernik, 1987; U.S. Environmental Protection Agency, 1997) encompasses approximately 17,871 km² (6,900 mi²...
Authors
Christopher E. Soulard, Christian G. Raumann, Tamara S. Wilson

Southern Rockies Ecoregion: Chapter 8 in Status and trends of land change in the Western United States--1973 to 2000 Southern Rockies Ecoregion: Chapter 8 in Status and trends of land change in the Western United States--1973 to 2000

The Southern Rockies Ecoregion is a high-elevation mountainous ecoregion that covers approximately 138,854 km2 (53,612 mi2), including much of central Colorado and parts of southern Wyoming and northern New Mexico (fig. 1) (Omernik, 1987; U.S. Environmental Protection Agency, 1997). It abuts six other ecoregions: the Wyoming Basin and Colorado Plateaus Ecoregions on the north and west...
Authors
Mark A. Drummond

Southwest Washington littoral drift restoration—Beach and nearshore morphological monitoring Southwest Washington littoral drift restoration—Beach and nearshore morphological monitoring

A morphological monitoring program has documented the placement and initial dispersal of beach nourishment material (280,000 m3) placed between the Mouth of the Columbia River (MCR) North Jetty and North Head, at the southern end of the Long Beach Peninsula in southwestern Washington State. A total of 21 topographic surveys and 8 nearshore bathymetric surveys were performed between July...
Authors
Andrew W. Stevens, Guy Gelfenbaum, Peter Ruggiero, George M. Kaminsky

Spatial and seasonal variability of base flow in the Verde Valley, central Arizona, 2007 and 2011 Spatial and seasonal variability of base flow in the Verde Valley, central Arizona, 2007 and 2011

Synoptic base-flow surveys were conducted on streams in the Verde Valley, central Arizona, in June 2007 and February 2011 by the U.S. Geological Survey (USGS), in cooperation with the Verde River Basin Partnership, the Town of Clarkdale, and Yavapai County. These surveys, also known as seepage runs, measured streamflow under base-flow conditions at many locations over a short period of...
Authors
Bradley D. Garner, Donald J. Bills

Spatial and temporal dynamics of cyanotoxins and their relation to other water quality variables in Upper Klamath Lake, Oregon, 2007-09 Spatial and temporal dynamics of cyanotoxins and their relation to other water quality variables in Upper Klamath Lake, Oregon, 2007-09

Phytoplankton blooms dominated by cyanobacteria that occur annually in hypereutrophic Upper Klamath Lake, Oregon, produce microcystins at concentrations that may contribute to the decline in populations of endangered Lost River (Deltistes luxatus) and shortnose (Chasmistes brevirostris) suckers. During 2007–09, water samples were collected from Upper Klamath Lake to determine the...
Authors
Sara L. Caldwell Eldridge, Tamara M. Wood, Kathy R. Echols

Spatial and temporal trends in runoff at long-term streamgages within and near the Chesapeake Bay Watershed Spatial and temporal trends in runoff at long-term streamgages within and near the Chesapeake Bay Watershed

Long-term streamflow data within the Chesapeake Bay watershed and surrounding area were analyzed in an attempt to identify trends in streamflow. Data from 30 streamgages near and within the Chesapeake Bay watershed were selected from 1930 through 2010 for analysis. Streamflow data were converted to runoff and trend slopes in percent change per decade were calculated. Trend slopes for...
Authors
Karen C. Rice, Robert M. Hirsch

Specific conductance measurements in central and western New York streams - A retrospective characterization Specific conductance measurements in central and western New York streams - A retrospective characterization

U.S. Geological Survey (USGS) Data Rescue Program funds were used to recover data from paper records for 139 streamgages across central and western New York State; 6,133 different streamflow measurement forms, collected between 1970-80, contained field water-quality measurements. The water-quality data were entered, reviewed, and uploaded into the USGS National Water Information System...
Authors
William M. Kappel, Gaylen J. Sinclair, James E. Reddy, David A. Eckhardt, M. Peter deVries, Margaret E. Phillips

Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions

Ground motion prediction equations (GMPEs) for elastic response spectra, including the Next Generation Attenuation (NGA) models, are typically developed at a 5% viscous damping ratio. In reality, however, structural and non-structural systems can have damping ratios other than 5%, depending on various factors such as structural types, construction materials, level of ground motion...
Authors
Sanaz Rezaeian, Yousef Bozorgnia, I.M. Idriss, Kenneth Campbell, Norman Abrahamson, Walter Silva

St. Petersburg Coastal and Marine Science Center's Core Archive Portal St. Petersburg Coastal and Marine Science Center's Core Archive Portal

This Web site contains information on rock cores archived at the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC). Archived cores consist of 3- to 4-inch-diameter coral cores, 1- to 2-inch-diameter rock cores, and a few unlabeled loose coral and rock samples. This document - and specifically the archive Web site portal - is intended to be a 'living'...
Authors
Chris Reich, Matt Streubert, Brendan Dwyer, Meg Godbout, Adis Muslic, Dan Umberger

State of the Earth’s cryosphere at the beginning of the 21st century: Glaciers, global snow cover, floating ice, and permafrost and periglacial environments State of the Earth’s cryosphere at the beginning of the 21st century: Glaciers, global snow cover, floating ice, and permafrost and periglacial environments

This chapter is the tenth in a series of 11 book-length chapters, collectively referred to as “this volume,” in the series U.S. Geological Survey Professional Paper 1386, Satellite Image Atlas of Glaciers of the World. In the other 10 chapters, each of which concerns a specific glacierized region of Earth, the authors used remotely sensed images, primarily from the Landsat 1, 2, and 3...
Authors
Richard S. Williams, Thomas G. Huntington, Jane G. Ferrigno, Lonnie Thompson, M.B. Dyurgerov, Mark Meier, Bruce Raup, Jeffrey S. Kargel, Dorothy K. Hall, David A. Robinson, Claire L. Parkinson, D. Cavalieri, Martin O Jeffries, K. Morris, Claude R. Duguay, J. A. Heginbottom, Jerry Brown, Ole Humlum, Harald Svensson, Kevin M. Foley
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