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At least 307 records · Page 17Linked to original sources

A new Enceladus global control network, image mosaic, and updated pointing kernels from Cassini's thirteen-year mission

NASA's Cassini spacecraft spent 13 years exploring the Saturn system, including 23 targeted flybys of the small, geologically active moon Enceladus. These flybys provided a wealth of image data from Cassini's Imaging Science Subsystem. To improve the usability of the Enceladus data set, we created a new, global photogrammetric control network for Enceladus that enabled compilation of a versatile cartographic package to support geologic mapping and other investigations. The network used 586 images in four image filters with a pixel scale generally between 50 and 500 m per pixel and a phase angle less than 120° and consisted of 10,362 tie points and 173,704 individual image measures, averaging nearly 17 measures per tie point. Least squares bundle adjustment resulted in a root‐mean‐square residual of 0.45 pixel, corresponding to root‐mean‐square ground point uncertainties of 66, 51, and 46 m in latitude, longitude, and radius, respectively. Using our geodetic control network, we created new global image mosaics, coregistered flyby mosaics to support geologic mapping, and updated pointing kernels for every image used in the solution. These products, including the updated pointing kernels, are available to the community through NASA's Planetary Data System Imaging Annex. The bundle adjustment solution also yielded independently determined shape information, resulting in radii within the stated uncertainty of International Astronomical Union values. The challenges of the data set, and the technical methodology described here are applicable to bodies imaged during multiple flybys with variable viewing and illumination geometry, including other midsized satellites of Saturn, and the Europa Clipper mission.

Earth and Space Science↗

Importance of the Lu-Hf isotopic system in studies of planetary chronology and chemical evolution

The 176 Lu- 176 Hf isotope method and its applications in earth sciences are discussed. Greater fractionation of Lu/Hf than Sm/Nd in planetary magmatic processes makes 176 Hf 177 Hf "> 176 Hf 177 Hf a powerful geochemical tracer. In general, proportional variations of 176 Hf 177 Hf "> 176 Hf 177 Hf exceed those of 143 Nd l44 Nd "> 143 Nd 144 Nd by factors of 1.5–3 in terrestrial and lunar materials. Lu-Hf studies therefore have a major contribution to make in understanding of terrestrial and other planetary evolution through time, and this is the principal importance of Lu-Hf. New data on basalts from oceanic islands show unequivocally that whereas considerable divergences occur in 176 Hf 177 Hf - 87 Sr 86 Sr "> 176 Hf 177 Hf- 87 Sr 86 Sr and 143 Nd l44 Nd - 87 Sr 86 Sr "> 143 Nd 144 Nd- 87 Sr 86 Sr diagrams, 176 Hf 177 Hf "> 176 Hf 177 Hf and 143 Nd 144 Nd "> 1 43 Nd 144 Nd display a single, linear isotopic variation in the suboceanic mantle. These discordant 87 Sr 86 Sr "> 87 Sr 86 Sr relationships may allow, with the acquisition of further Hf-Nd-Sr isotopic data, a distinction between processes such as mantle metasomatism, influence of seawater-altered material in the magma source, or recycling of sediments into the mantle. In order to evaluate the Hf-Nd isotopic correlation in terms of mantle fractionation history, there is a need for measurements of Hf distribution coefficients between silicate minerals and liquids, and specifically for a knowledge of Hf behavior in relation to rareearth elements. For studying ancient terrestrial Hf isotopic variations, the best quality Hf isotope data are obtained from granitoid rocks or zircons. New data show that very U-Pb discordant zircons may have upwardly-biased 176 Hf 177 Hf "> 176 Hf 177 Hf , but that at least concordant to slightly discordant zircons appear to be reliable carriers of initial 176 Hf 177 Hf "> 176 Hf 177 Hf . Until the controls on addition of radiogenic Hf to zircon are understood, combined zircon-whole rock studies are recommended. Lu-Hf has been demonstrated as a viable tool for dating of ancient terrestrial and extraterrestrial samples, but because it offers little advantage over existing methods, is unlikely to find wide application in pure chronological studies.

Geochimica et Cosmochimica Acta↗

EAARL Coastal Topography-Cape Hatteras National Seashore, North Carolina, Post-Nor'Ida, 2009: Bare Earth

These remotely sensed, geographically referenced elevation measurements of lidar-derived bare-earth (BE) topography datasets were produced collaboratively by the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL, and the National Park Service (NPS), Northeast Coastal and Barrier Network, Kingston, RI. This project provides highly detailed and accurate datasets of a portion of the National Park Service Southeast Coast Network's Cape Hatteras National Seashore in North Carolina, acquired post-Nor'Ida (November 2009 nor'easter) on November 27 and 29 and December 1, 2009. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative airborne lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multispectral color-infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine aircraft, but the instrument was deployed on a Pilatus PC-6. A single pilot, a lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

Data Series↗

Wetlands

During the last decades, soil organic carbon (SOC) attracted the attention of a much wider array of specialists beyond agriculture and soil science, as it was proven to be one of the most crucial components of the earth’s climate system, which has a great potential to be managed by humans. Soils as a carbon pool are one of the key factors in several Sustainable Development Goals, in particular Goal 15, “Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification and halt and reverse land degradation and halt biodiversity loss” with the SOC stock being explicitly cited in Indicator 15.3.1. This technical manual is the first attempt to gather, in a standardized format, the existing data on the impacts of the main soil management practices on SOC content in a wide array of environments, including the advantages, drawbacks, and constraints. This manual presents different sustainable soil management (SSM) practices at different scales and in different contexts, supported by case studies that have been shown with quantitative data to have a positive effect on SOC stocks and successful experiences of SOC sequestration in practical field applications Volume 2 includes a description of hot spots of SOC stocks. This manual defines hot spots of SOC as areas that represent a proportionally little of the global land surface but on which SOC storage is highly effective; bright spots as large land areas with low SOC stocks per km2 that represent a potential for further carbon sequestration.

Report↗

Solar-system-wide significance of Mars polar science

1. The North Polar Layered Deposits contain thousands of ice layers that record accumulation and climate history for at least several million years, making the most accessible and most complete climate record aside from the Earth’s – and the only one to record the impact of large obliquity shifts. 2. Mars Polar Science is a diverse and integrated system spanning much of the planet, above and below the surface: geographic poles, mid- and high-latitudes, numerous active volatile processes that interact with the near-surface, and the lower and middle atmosphere circulations, even influencing the upper atmosphere and atmospheric escape. 3. Mars polar processes serves as an analogue and scientific link to numerous solar system bodies. Mars has two volatile cycles that influence surface processes, atmospheric processes, and climate cycles. Mars, with many data sets and observations, serves as a proxy for outer planets and moons that undergo the same physics but with other volatile species. Additionally, technology designed for Mars polar exploration benefits exploration elsewhere. 4. Mars Polar and Atmospheric Science results are critical for future human exploration and in situ resources and the study of planetary habitability.

Bulletin of the AAS↗

Soil-water dynamics and unsaturated storage during snowmelt following wildfire

Many forested watersheds with a substantial fraction of precipitation delivered as snow have the potential for landscape disturbance by wildfire. Little is known about the immediate effects of wildfire on snowmelt and near-surface hydrologic responses, including soil-water storage. Montane systems at the rain-snow transition have soil-water dynamics that are further complicated during the snowmelt period by strong aspect controls on snowmelt and soil thawing. Here we present data from field measurements of snow hydrology and subsurface hydrologic and temperature responses during the first winter and spring after the September 2010 Fourmile Canyon Fire in Colorado, USA. Our observations of soil-water content and soil temperature show sharp contrasts in hydrologic and thermal conditions between north- and south-facing slopes. South-facing burned soils were ∼1–2 °C warmer on average than north-facing burned soils and ∼1.5 °C warmer than south-facing unburned soils, which affected soil thawing during the snowmelt period. Soil-water dynamics also differed by aspect: in response to soil thawing, soil-water content increased approximately one month earlier on south-facing burned slopes than on north-facing burned slopes. While aspect and wildfire affect soil-water dynamics during snowmelt, soil-water storage at the end of the snowmelt period reached the value at field capacity for each plot, suggesting that post-snowmelt unsaturated storage was not substantially influenced by aspect in wildfire-affected areas. Our data and analysis indicate that the amount of snowmelt-driven groundwater recharge may be larger in wildfire-impacted areas, especially on south-facing slopes, because of earlier soil thaw and longer durations of soil-water contents above field capacity in those areas.

Hydrology and Earth System Sciences↗

40Ar/39Ar and U-Th-Pb dating of separated clasts from the Abee E4 chondrite

Determinations of 40 Ar/ 39 Ar and U-Th-Pb are reported for three clasts from the Abee (E4) enstatite chondrite, which has been the object of extensive consortium investigations. The clasts give 40 Ar/ 39 Ar plateau ages and/or maximum ages of 4.5 Gy, whereas two of the clasts give average ages of 4.4 Gy. Within the range of 4.4–4.5 Gy these data do not resolve any possible age differences among the three clasts. 206 Pb measured in these clasts is only ∼1.5–2.5% radiogenic, which leads to relatively large uncertainties in the Pb isochron age and in the 207 Pb/ 206 Pb model ages. The Pb data indicate that the initial 207 Pb/ 206 Pb was no more than 0.08±0.07% higher than this ratio in Can˜on Diablo troilite. The U-Th-Pb data are consistent with the interpretation that initial formation of these clasts occurred 4.58 Gy ago and that the clasts have since remained closed systems, but are contaminated with terrestrial Pb. The 40 Ar/ 39 Ar ages could be gas retention ages after clast formation or impact degassing ages. The thermal history of Abee deduced from Ar data appears consistent with that deduced from magnetic data, and suggests that various Abee components experienced separate histories until brecciation no later than 4.4 Gy ago, and experienced no appreciable subsequent heating.

Earth and Planetary Science Letters↗

Publications of Western Earth Surface Processes Team 2001

The Western Earth Surface Processes Team (WESPT) of the U.S. Geological Survey (USGS) conducts geologic mapping and related topical earth-science studies in the Western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues, such as ground-water quality, landslides and other potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2001 included southern California, the San Francisco Bay region, the Pacific Northwest, and the Las Vegas urban corridor. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the Western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 2001, as well as additional 1999 and 2000 publications that were not included in the previous list (USGS Open-File Report 00–215 and USGS Open-File Report 01–198). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Many of these web publications are USGS Open-File Reports that contain large digital databases of geologic map and related information.

Open-File Report↗

Publications of the Western Earth Surface Processes Team 2002

The Western Earth Surface Processes Team (WESPT) of the U.S. Geological Survey (USGS) conducts geologic mapping and related topical earth science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, landslides and other potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2001 included southern California, the San Francisco Bay region, the Pacific Northwest, and the Las Vegas urban corridor. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 2002 as well as additional 1998 and 2001 publications that were not included in the previous list (USGS Open-File Report 00-215, USGS Open-File Report 01-198, and USGS Open-File Report 02-269). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Many of these web publications are USGS open-file reports that contain large digital databases of geologic map and related information. Information on ordering USGS publications can be found on the World Wide Web or by calling 1-888-ASK-USGS. The U.S. Geological Survey’s web server for geologic information in the western United States is located at http://geology.wr.usgs.gov. More information is available about the WESPT is available on-line at the team website.

Open-File Report↗

Publications of the Western Geologic Mapping Team 1997-1998

The Western Geologic Mapping Team (WGMT) of the U.S. Geological Survey, Geologic Division (USGS, GD), conducts geologic mapping and related topical earth-science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, potential geologic hazards, and land-use decisions. Areas of primary emphasis currently include southern California, the San Francisco Bay region, the Pacific Northwest, the Las Vegas urban corridor, and selected National Park lands. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the western United States. The results of research conducted by the WGMT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WGMT released in calendar years 1997 and 1998. Most of the publications listed were authored or coauthored by WGMT staff. However, the list also includes some publications authored by formal non-USGS cooperators with the WGMT, as well as some authored by USGS staff outside the WGMT in cooperation with WGMT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Most of these Web publications are USGS open-file reports that contain large digital databases of geologic map and related information. For these, the bibliographic citation refers specifically to an explanatory pamphlet containing information about the content and accessibility of the database, not to the actual map or related information comprising the database itself.

Open-File Report↗

An improved empirical model for predicting postfire debris-flow volume in the western United States

Reliable estimates of debris-flow volume can be used to help predict the magnitude of debris-flow hazards following wildfire in the western United States. In this study, we compiled and used a database of 227 postfire debris-flow volumes that were collected across the western United States to develop a multiple linear regression model for predicting postfire debris-flow volume. We explored 36 predictor variables related to rainfall, terrain, and fire characteristics, and selected the model with the combination of variables that yielded the most accurate predictions of debris-flow volume. We evaluated model performance against the entire volume database, as well as against four subsets of volume data from southern California, the Intermountain West, the Southwest, and regions with limited volume data, such as northern California and Washington. We also compared model performance against 3 existing postfire debris-flow volume models that were developed for use in southern California, the Intermountain West, and the Southwest. We demonstrate that the new volume model performs as well as the regional models in the regions for which they were developed and outperforms existing models when applied to volumes from data-limited regions in the western United States. These results indicate that the debris-flow volume model introduced in this study can be used to improve postfire hazard assessments across the western United States, especially outside of southern California.

Arizona, California, Colorado, New Mexico, Utah, W↗

Precision measurement of lead isotopes ratios: preliminary analyses from the U.S. mine, Bingham Canyon, Utah

A gas-source mass spectrometer has been constructed for the precise measurement of lead isotope ratios. Sixteen analyses on 4 different preparations of the same galena made over a period of 2 months gave 95% confidence limits (per analysis) of 206 Pb/ 204 Pb= 0.080%, 207 Pb/ 206 Pb= 0.042%and 208 Pb/ 206 Pb= 0.046% . Eight samples from the U.S. mine in the Bingham district have a linear relationship over the 1% range of their 206 Pb/ 204 Pb ratios. The simplest model fitting these data suggests that the lead was separated from a primary system (μ=8.98) 1630±150m.y. ago and subsequently mixed with a radiogenic lead of similar age; biotite K-Ar dates for altered intrusive rocks associated with the ores provide an apparent age of mineralization and suggest that isotopic evolution of the lead was terminated about 36 m.y. ago.

Utah↗

Publications of the Western Earth Surface Processes Team 2000

The Western Earth Surface Processes Team (WESP) of the U.S. Geological Survey (USGS) conducts geologic mapping and related topical earth science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2000 included southern California, the San Francisco Bay region, the Pacific Northwest, the Las Vegas urban corridor, and selected National Park lands. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 2000 as well as additional 1999 publications that were not included in the previous list (USGS Open-file Report 00-215). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Many of these Web publications are USGS open-file reports that contain large digital databases of geologic map and related information.

Open-File Report↗

Land-Use Portfolio Modeler, Version 1.0

Natural hazards pose significant threats to the public safety and economic health of many communities throughout the world. Community leaders and decision-makers continually face the challenges of planning and allocating limited resources to invest in protecting their communities against catastrophic losses from natural-hazard events. Public efforts to assess community vulnerability and encourage loss-reduction measures through mitigation often focused on either aggregating site-specific estimates or adopting standards based upon broad assumptions about regional risks. The site-specific method usually provided the most accurate estimates, but was prohibitively expensive, whereas regional risk assessments were often too general to be of practical use. Policy makers lacked a systematic and quantitative method for conducting a regional-scale risk assessment of natural hazards. In response, Bernknopf and others developed the portfolio model, an intermediate-scale approach to assessing natural-hazard risks and mitigation policy alternatives. The basis for the portfolio-model approach was inspired by financial portfolio theory, which prescribes a method of optimizing return on investment while reducing risk by diversifying investments in different security types. In this context, a security type represents a unique combination of features and hazard-risk level, while financial return is defined as the reduction in losses resulting from an investment in mitigation of chosen securities. Features are selected for mitigation and are modeled like investment portfolios. Earth-science and economic data for the features are combined and processed in order to analyze each of the portfolios, which are then used to evaluate the benefits of mitigating the risk in selected locations. Ultimately, the decision maker seeks to choose a portfolio representing a mitigation policy that maximizes the expected return-on-investment, while minimizing the uncertainty associated with that return-on-investment. The portfolio model, now known as the Land-Use Portfolio Model (LUPM), provided the framework for the development of the Land-Use Portfolio Modeler, Version 1.0 software (LUPM v1.0). The software provides a geographic information system (GIS)-based modeling tool for evaluating alternative risk-reduction mitigation strategies for specific natural-hazard events. The modeler uses information about a specific natural-hazard event and the features exposed to that event within the targeted study region to derive a measure of a given mitigation strategy`s effectiveness. Harnessing the spatial capabilities of a GIS enables the tool to provide a rich, interactive mapping environment in which users can create, analyze, visualize, and compare different

Techniques and Methods↗

EAARL coastal topography-western Florida, post-Hurricane Charley, 2004: seamless (bare earth and submerged.

Project Description These remotely sensed, geographically referenced elevation measurements of lidar-derived seamless (bare-earth and submerged) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Coastal and Marine Geology Program (CMGP), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the western Florida coastline beachface, acquired post-Hurricane Charley on August 17 and 18, 2004. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative airborne lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multispectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation. For more information about similar projects, please visit the Decision Support for Coastal Science and Management website. Selected References Brock, J.C., Wright, C.W., Sallenger, A.H., Krabill, W.B., and Swift, R.N., 2002, Basis and methods of NASA airborne topographic mapper Lidar surveys for coastal studies: Journal of Coastal Research, v. 18, no. 1, p. 1-13. Crane, Michael, Clayton, Tonya, Raabe, Ellen, Stoker, Jason, Handley, Larry, Bawden, Gerald, Morgan, Karen, and Queija, Vivian, 2004, Report of the U.S. Geological Survey Lidar workshop sponsored by the Land Remote Sensing Program and held in St. Petersburg, FL, November 2002: U.S. Geological Survey Open-File Report 2004-1456, 72 p. Nayegandhi, Amar, Brock, J.C., and Wright, C.W., 2009, Small-footprint, waveform-resolving Lidar estimation of submerged and sub-canopy topography in coastal environments: International Journal of Remote Sensing, v. 30, no. 4, p. 861-878. Sallenger, A.H., Wright, C.W., and Lillycrop, Jeff, 2005, Coastal impacts of the 2004 hurricanes measured with airborne Lidar; initial results: Shore and Beach, v. 73, nos. 2-3, p. 10-14. Resources Included Readme.txt File

Data Series↗

Publications of the Western Earth Surfaces Processes Team 2005

Introduction The Western Earth Surface Processes Team (WESPT) of the U.S. Geological Survey (USGS) conducts geologic mapping, earth-surface process investigations, and related topical earth science studies in the western United States. This work is focused on areas where modern geologic maps and associated earth-science data are needed to address key societal and environmental issues such as ground-water quality, landslides and other potential geologic hazards, and land-use decisions. Areas of primary emphasis in 2005 included southern California, the San Francisco Bay region, the Mojave Desert, the Colorado Plateau region of northern Arizona, and the Pacific Northwest. The team has its headquarters in Menlo Park, California, and maintains smaller field offices at several other locations in the western United States. The results of research conducted by the WESPT are released to the public as a variety of databases, maps, text reports, and abstracts, both through the internal publication system of the USGS and in diverse external publications such as scientific journals and books. This report lists publications of the WESPT released in 2005 as well as additional 2002, 2003, and 2004 publications that were not included in the previous lists (USGS Open-File Reports 03-363, 2004- 1267, 2005-1362). Most of the publications listed were authored or coauthored by WESPT staff. The list also includes some publications authored by non-USGS cooperators with the WESPT, as well as some authored by USGS staff outside the WESPT in cooperation with WESPT projects. Several of the publications listed are available on the World Wide Web; for these, URL addresses are provided. Many of these web publications are USGS Open-File reports that contain large digital databases of geologic map and related information. Information on ordering USGS publications can be found on the World Wide Web at http://www.usgs.gov/pubprod/, or by calling 1-888-ASK-USGS. The U.S. Geological Survey's web server for geologic information in the western United States is located at http://geology.wr.usgs.gov/. More information is available about the WESPT is available on-line at http://geology.wr.usgs.gov/wgmt.

Open-File Report↗

Assessing the potential hydrological impact of the Gibe III Dam on Lake Turkana water level using multi-source satellite data

Lake Turkana, the largest desert lake in the world, is fed by ungauged or poorly gauged river systems. To meet the demand of electricity in the East African region, Ethiopia is currently building the Gibe III hydroelectric dam on the Omo River, which supplies more than 80% of the inflows to Lake Turkana. On completion, the Gibe III dam will be the tallest dam in Africa with a height of 241 m. However, the nature of interactions and potential impacts of regulated inflows to Lake Turkana are not well understood due to its remote location and unavailability of reliable in-situ datasets. In this study, we used 12 years (1998–2009) of existing multi-source satellite and model-assimilated global weather data. We use calibrated multi-source satellite data-driven water balance model for Lake Turkana that takes into account model routed runoff, lake/reservoir evapotranspiration, direct rain on lakes/reservoirs and releases from the dam to compute lake water levels. The model evaluates the impact of Gibe III dam using three different approaches such as (a historical approach, a knowledge-based approach, and a nonparametric bootstrap resampling approach) to generate rainfall-runoff scenarios. All the approaches provided comparable and consistent results. Model results indicated that the hydrological impact of the dam on Lake Turkana would vary with the magnitude and distribution of rainfall post-dam commencement. On average, the reservoir would take up to 8–10 months, after commencement, to reach a minimum operation level of 201 m depth of water. During the dam filling period, the lake level would drop up to 2 m (95% confidence) compared to the lake level modelled without the dam. The lake level variability caused by regulated inflows after the dam commissioning were found to be within the natural variability of the lake of 4.8 m. Moreover, modelling results indicated that the hydrological impact of the Gibe III dam would depend on the initial lake level at the time of dam commencement. Areas along the Lake Turkana shoreline that are vulnerable to fluctuations in lake levels were also identified. This study demonstrates the effectiveness of using existing multi-source satellite data in a basic modeling framework to assess the potential hydrological impact of an upstream dam on a terminal downstream lake. The results obtained from this study could also be used to evaluate alternate dam-filling scenarios and assess the potential impact of the dam on Lake Turkana under different operational strategies.

Hydrology and Earth System Sciences Discussions↗

Data management and digital delivery of analog data

The U.S. Geological Survey's (USGS) data archive at the Earth Resources Observation and Science (EROS) Center is a comprehensive and impartial record of the Earth's changing land surface. USGS/EROS has been archiving and preserving land remote sensing data for over 35 years. This remote sensing archive continues to grow as aircraft and satellites acquire more imagery. As a world leader in preserving data, USGS/EROS has a reputation as a technological innovator in solving challenges and ensuring that access to these collections is available. Other agencies also call on the USGS to consider their collections for long-term archive support. To improve access to the USGS film archive, each frame on every roll of film is being digitized by automated high performance digital camera systems. The system robotically captures a digital image from each film frame for the creation of browse and medium resolution image files. Single frame metadata records are also created to improve access that otherwise involves interpreting flight indexes. USGS/EROS is responsible for over 8.6 million frames of aerial photographs and 27.7 million satellite images.

Conference Paper↗