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Results for “Eos, Transactions, American Geophysical Union”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 163 records · Page 9Linked to original sources
USGS2012

River turbidity and sediment loads during dam removal

Dam decommissioning has become an important means for removing unsafe or obsolete dams and for restoring natural fluvial processes, including discharge regimes, sediment transport, and ecosystem connectivity [Doyle et al., 2003]. The largest dam-removal project in history began in September 2011 on the Elwha River of Washington State (Figure 1a). The project, which aims to restore the river ecosystem and increase imperiled salmon populations that once thrived there, provides a unique opportunity to better understand the implications of large-scale river restoration.

Washington↗
USGS2012

A meeting of the waters: interdisciplinary challenges and opportunities in tidal rivers

At the interface of estuarine tides and freshwater rivers lie wetland and aquatic ecosystems, which experience dramatic effects of sea level rise. There, nontidal channels and riparian floodplains are transforming into tidal ecosystems, and tidal freshwater ecosystems are receiving increasing salinity. These river-floodplain systems have both fluvial characteristics, including meandering channels and expansive floodplain forests, and estuarine characteristics, including tides and intertidal wetlands [see Barendregt et al., 2009; Conner et al., 2007, and references therein]. Because tidal rivers lie at the disciplinary divide between fluvial and estuarine science, a knowledge gap has developed in scientists' understanding of the geomorphic and biogeochemical response of these environments to sea level rise, climate change, and anthropogenically driven variations in watershed exports.

Eos, Transactions, American Geophysical Union↗
USGS2012

Progress on archiving, delivering, and working with planetary data

Planetary Data: A Workshop for Users and Software Developers 2012; Flagstaff, Ariz., 25–29 June 2012 The recent boom in the volume of data returned by planetary science missions continues to delight and confound users. Recently the NASA Planetary Data System (PDS) has seen an approximately 50‐fold increase in the amount of archived data and now serves nearly half a petabyte. Within 5 years, this volume likely will approach 1 petabyte. While archivists, users, and developers have done a creditable job of providing search and download functions and analysis and visualization tools, the wealth of data necessitates more discussion between users and developers about current limitations and desired improvements.

Eos, Transactions, American Geophysical Union↗
USGS2012

Expanded stream gauging includes groundwater data and trends

Population growth has increased water scarcity to the point that documenting current amounts of worldwide water resources is now as critical as any data collection in the Earth sciences. As a key element of this data collection, stream gauges yield continuous hydrologic information and document long-term trends, recording high-frequency hydrologic information over decadal to centennial time frames.

Eos, Transactions, American Geophysical Union↗
USGS2012

John B. "Jack" Townshend (1927-2012)

Jack Townshend, geophysicist and dedicated public servant, died on 13 August 2012 in Fairbanks, Alaska. He was 85. Jack's career with the federal government, most of it with the national magnetic observatory program, spanned more than six solar cycles of time, and he retired only days before his death. The duration of Jack's career encompassed an important period in the history of the advancement of our understanding of the Earth. Jack's career of contributions, his life, and his personality are worthy of retrospective celebration.

Eos, Transactions, American Geophysical Union↗
USGS2017

Defining opportunities for collaboration across data life cycles

Monitoring natural resources - water, forests, and animal populations—is required to support effective management of natural resources. However, because monitoring activities are often specific to a discipline, issue, or agency, it is typically difficult to integrate data to answer questions that transcend geopolitical and jurisdictional boundaries. How do we reach the better data integration we need?

Eos, Transactions, American Geophysical Union↗
USGS2019

Better approaches to managing drought in the American Southwest

The second in a series of USGS Southwest Region (SWR) “Science Exchange” annual workshops, focused on USGS drought science. The participants considered how extreme drought conditions are evolving in much of the American southwest, with an emphasis on integrated drought science planning at the USGS bureau and program levels. The increased need for interdisciplinary science to support resource-management decisions systems, was highlighted. The workshop brought together scientists and program managers from USGS with Bureau of Land Management, National Oceanic and Atmospheric Administration, US Bureau of Reclamation and state water management departments. Key objectives of the workshop were to improve awareness of ongoing drought-science work within the region, highlight the capabilities of USGS-SWR science centers in drought science, and build new relationships to advance best approaches in drought science. Topics covered in presentations and demonstrations were broad-ranging and included monitoring for drought early warning; water use and water production associated with petroleum production; paleo perspectives on drought, and ecological consequences of drought to native fish.

Eos, Transactions, American Geophysical Union↗
USGS2011

The case for planetary sample return missions

The essential role of planetary sample studies in exploration of the solar system has been well established “Drake et al., 1987”. As part of the larger pursuit of comparative planetology, samples of other rocky planets (Mercury, Venus, Mars), planetary satellites, asteroids, and comets should reveal much about the materials and processes that formed Earth. In that context, Mars is an especially appealing sample target because of its distinctive, Earth‐like characteristics. Here, we review the scientific objectives and justifications for collecting documented samples of Mars and returning them to Earth for laboratory study. A Mars sample‐return mission will be technologically challenging but represents the only way to acquire definitive knowledge about formation of the planet, its geologic and climatic history, and its potential as a haven of life.

Eos, Transactions, American Geophysical Union↗
USGS2011

Shaded relief map of US topography from digital elevations

Much geologic and geophysical information that lies encoded within land surface form can be revealed by image processing large files of digitized elevations in fast machines and mapping the results. This convergence of computers, analytic software, data, and output devices has created exciting opportunities for automating the numerical and spatial study of topography. One recent result is the accompanying shaded relief map of the conterminous 48 states. A shaded relief image of topography mimics a cloud-free monochrome aerial photograph taken at low Sun. Gray tones represent different terrain slopes and azimuths calculated from adjacent elevations stored in a uniform grid, or digital elevation model (DEM). Sun elevation and direction can be varied to generate complementary views of the same area. The synoptic coverage of these computer images is a major advantage; unlike a photograph, image extent is limited only by size of the elevation array. Shaded relief maps also are free of the distortion found in radar images and of the vegetation and cultural features that mask topographic form on Landsat and SPOT images.

Eos, Transactions, American Geophysical Union↗
USGS2006

National workshop on gas hydrates

The range of present knowledge on the subject of gas hydrates and related federal research programs was the topic of discussion at the National Workshop on Gas Hydrates, April 23–24. The intention of the meeting was to provide the impetus for an expanded and broader‐based national research program in both academia and government. Held at the U.S. Geological Survey National Center, Reston, Va., the workshop was organized by Michael D. Max, Naval Research Laboratory, Washington, D.C.; William P. Dillon, USGS, Woods Hole, Mass.; and Rodney D. Malone, U.S. Department of Energy, Morgantown Energy Technology Center, Morgantown, W.Va. The 33 attendees represented academia (33%), federal agencies (58%), and industry (9%).

Eos, Transactions, American Geophysical Union↗
USGS2006

The Pu'u ‘O’o‐Kupaianaha eruption of Kilauea

Kilauea is nearing the 10th year of its most voluminous rift zone eruption in the last 2 centuries. Lava flows have covered 75 km 2 to depths as great as 25 m and have added almost 1.2 km 2 of new land to the island. These flows have devastated downslope communities and have provided a painful tutorial for local government in planning for and living with volcanic hazards [ Heliker and Wright , 1991]. At the same time, the accessibility and longevity of this eruption have provided a unique opportunity for quantitative studies requiring long‐term observations. This article briefly summarizes these studies, which are directed at a better understanding of eruption mechanics, lava‐flow field emplacement, and the plumbing system of Kilauea.

Hawaii↗
USGS2006

Mini-Sosie high-resolution seismic method aids hazards studies

A dramatic example of just how catastrophic earthquake damage can be occurred in 1989, when a nationally televised World Series game in San Francisco was preempted by the M 7.1 Loma Prieta earthquake. The surprising amount and distribution of damage reinforce the importance of seismic-hazard studies in urban areas, where potential for damage and loss of life is greatest. Unfortunately, many large urban centers developed before the advent of seismic-hazard microzonation mapping, ground-response building codes, and standardized air-photo reconnaissance. Decades of building, paving, and utility installation have modified the land surface to the extent that surficial geologic expression of faults and evidence of prehistoric earthquakes are either inaccessible or totally obliterated.

Eos, Transactions, American Geophysical Union↗
USGS2011

Mt. Spurr's 1992 eruptions

On June 27, 1992, the Crater Peak vent on the south side of Mt. Spurr awoke from 39 years of dormancy and burst into subplinian eruption after 10 months of elevated seismicity. Two more eruptions followed in August and September. The volcano lies 125-km west of Anchorage, which is Alaska's largest city and an important international hub for air travel. The Alaska Volcano Observatory (AVO) was able to warn communities and the aviation industry well in advance of these eruptions.

Alaska↗
USGS2011

Loma Prieta damage largely attributed to enhanced ground shaking

Earthquake hazards are commonly treated independently by Earth scientists, yet when a large earthquake occurs, property losses are seldom totaled separately for each earthquake hazard. Four years after the 1989 Loma Prieta earthquake rolled through northern California, a quantitative answer to the following question is not yet available: How much damage was caused by ground shaking, liquefaction, landslides, tectonic ground rupture, or tsunami? Although the consequences of one earthquake do not necessarily follow for others, an answer to this question will help guide public policy and set research priorities. The cost effectiveness of earthquake hazard mitigation can be improved when the relative significance of earthquake hazards is known because it enables public agencies to concentrate mitigation efforts on the most portentous hazards.

Eos, Transactions, American Geophysical Union↗
USGS2006

Strides made in understanding Antarctic stratigraphy and Cenozoic glacial history

It is known that the Antarctic ice sheet greatly affected global climate, sea‐level, ocean circulation, and Southern Hemisphere biota during Cenozoic times, but until recently, how remained largely a mystery. Because few Cenozoic rocks are exposed on the Antarctic continent, the only way to investigate the evolution of the Antarctic ice sheet was through isotopic studies on distant deep‐ocean sediments. The success of these studies was limited—isotopic studies and low‐latitude sea level variation yielded different glacial ice volumes. To take study of Cenozoic Antarctic glaciations and their effects a step further, the Antarctic Offshore Acoustic Stratigraphy project (ANTOSTRAT) assembled a contingent of geoscientists from over 100 institutions in 32 countries. Since 1989, they have compiled and analyzed offshore acoustic and geologic data from the Antarctic continental margin, amassing over 150,000 km of multichannel seismic reflection data, tens of thousands of kilometers of single‐channel, high‐resolution seismic data, and over 1000 cores.

Eos, Transactions, American Geophysical Union↗
USGS2006

The global topography mission gains momentum

An accurate description of the surface elevation of the Earth is of fundamental importance to many branches of Earth science. Continental topographic data are required for studies of hydrology, ecology, glaciology, geomorphology, and atmospheric circulation. For example, in hydrologic and terrestrial ecosystem studies, topography exerts significant control on intercepted solar radiation, water runoff and subsurface water inventory, microclimate, vegetation type and distribution, and soil development. The topography of the polar ice caps and mountain glaciers directly reflects ice-flow dynamics and is closely linked to global climate and sea level change.

Eos, Transactions, American Geophysical Union↗
USGS2006

Mission in the works promises precise global topographic data

Significant deficiencies in the quality of today's topographic data severely limit scientific applications. Very few available data sets meet the stringent requirements of 10–30 m for global digital topography and 5 m or better vertical accuracy, and existing satellite systems are unlikely to fulfill these requirements. The Joint Topographic Science Working Group, appointed by NASA and the Italian Space Agency, concluded that radar interferometry coupled with a laser altimeter would be the most promising approach for improving data quality. By providing its own illumination at a wavelength Ion g enough to (e.g., λ = 25 cm) to penetrate clouds and rain, the interferometer would provide a global, uniform high-quality topographic data set. One mission under study, TOPSAT, is well positioned to fill this niche and promises to pave the way toward a more standardized and precise topographic database. TOPSAT would be an international mission, designed to make use of recent technology advances in such programs as NASA's New Millennium. It could be ready to launch by the end of this decade.

Eos, Transactions, American Geophysical Union↗
USGS2006

Progress made in groundwater flow and transport modeling

A special session, “Automated Parameter Identification and Sensitivity Analysis in Groundwater Flow and Transport,” was held at the Spring AGU meeting last May to explore recent scientific and technological developments in this expanding research area. The problems and approaches discussed are crucial to any field of Earth science in which models are used to represent physical processes and simulated values are compared with measured quantities. Although methods for automated parameter identification and sensitivity analysis were first developed at about the same time as numerical groundwater models, they are rarely used. Presentations at this special session clearly demonstrated the potential contributions of these methods for more insightful groundwater model development and calibration.

Eos, Transactions, American Geophysical Union↗