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Filters Date Range Past year (0) Past month (0) Past week (0) Past day (0) Custom range... To   Search Extensions Citation (53) Shapefile (9) Types Citation (53) Downloadable (9) Map Service (9) OGC WFS Layer (9) OGC WMS Layer (9) Shapefile (9) Contacts Voss, Clifford I. Wellman, Tristan P. Abraham, Jared D. Jorgenson, M. Torre Minsley, Burke J. More... Categories Data (9) View Results as: JSON ATOM CSV

Constraining the Inferred Paleohydrologic Evolution of a Deep Unsaturated Zone in the Amargosa Desert Categories: Publication; Types: Citation Airborne electromagnetic imaging of discontinuous permafrost Categories: Publication; Types: Citation CO2 dynamics in the Amargosa Desert: Fluxes and isotopic speciation in a deep unsaturated zone Categories: Publication; Types: Citation Airborne electromagnetic imaging of discontinuous permafrost The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering 1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past 4 million years and the configuration of permafrost to depths of 100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the... Categories: Data, Publication; Types: Citation, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: Baseline 1-High Resolution Landcover Imaging, Modeling, Monitoring 3-Improve Permafrost Mapping, and Monitoring Influence of permafrost distribution on groundwater flow in the context of climate-driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States Understanding the role of permafrost in controlling groundwater flow paths and fluxes is central in studies aimed at assessing potential climate change impacts on vegetation, species habitat, biogeochemical cycling, and biodiversity. Recent field studies in interior Alaska show evidence of hydrologic changes hypothesized to result from permafrost degradation. This study assesses the hydrologic control exerted by permafrost, elucidates modes of regional groundwater flow for various spatial permafrost patterns, and evaluates potential hydrologic consequences of permafrost degradation. The Yukon Flats Basin (YFB), a large (118,340 km super(2)) subbasin within the Yukon River Basin, provides the basis for this investigation.... Categories: Data, Publication; Types: Citation, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: Modeling, Monitoring 3-Improve Permafrost Mapping, and Monitoring Widespread Natural Perchlorate in Unsaturated Zones of the Southwest United States A substantial reservoir (up to 1 kg ha-1) of natural perchlorate is present in diverse unsaturated zones of the arid and semi-arid southwestern United States. The perchlorate co-occurs with meteoric chloride that has accumulated in these soils throughout the Holocene [0 to 10?15 ka (thousand years ago)] and possibly longer periods. Previously, natural perchlorate widely believed to be limited to the Atacama Desert, now appears widespread in steppe-to-desert ecoregions. The perchlorate reservoir becomes sufficiently large to affect groundwater when recharge from irrigation or climate change flushes accumulated salts from the unsaturated zone. This new source may help explain increasing reports of perchlorate in dry... Categories: Publication; Types: Citation Trends in streamflow in the Yukon River Basin from 1944 to 2005 and the influence of the Pacific Decadal Oscillation Categories: Publication; Types: Citation; Tags: M2-Standardized stream and lake information-1 Impacts of climate, lake size, and supra- and sub-permafrost groundwater flow on lake-talik evolution, Yukon Flats, Alaska (USA) Issue Title: Hydrogeology of Cold Regions In cold regions, hydrologic systems possess seasonal and perennial ice-free zones (taliks) within areas of permafrost that control and are enhanced by groundwater flow. Simulation of talik development that follows lake formation in watersheds modeled after those in the Yukon Flats of interior Alaska (USA) provides insight on the coupled interaction between groundwater flow and ice distribution. The SUTRA groundwater simulator with freeze-thaw physics is used to examine the effect of climate, lake size, and lake-groundwater relations on talik formation. Considering a range of these factors, simulated times for a through-going sub-lake talik to form through 90 m of permafrost... Categories: Publication; Types: Citation; Tags: M3-Improve Permafrost Mapping, Modeling, and Monitoring Extending Airborne Electromagnetic Surveys for Regional Active Layer and Permafrost Mapping with Remote Sensing and Ancillary Data, Yukon Flats Ecoregion, Central Alaska Machine-learning regression tree models were used to extrapolate airborne electromagnetic resistivity data collected along flight lines in the Yukon Flats Ecoregion, central Alaska, for regional mapping of permafrost. This method of extrapolation (r?=?0.86) used subsurface resistivity, Landsat Thematic Mapper (TM) at-sensor reflectance, thermal, TM-derived spectral indices, digital elevation models and other relevant spatial data to estimate near-surface (0?2.6-m depth) resistivity at 30-m resolution. A piecewise regression model (r?=?0.82) and a presence/absence decision tree classification (accuracy of 87%) were used to estimate active-layer thickness (ALT) (< 101?cm) and the probability of near-surface (up to... Categories: Data, Publication; Types: Citation, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: Baseline 1-High Resolution Landcover Imaging, Modeling, Monitoring 3-Improve Permafrost Mapping, and Monitoring Impacts of climate, lake size, and supra- and sub-permafrost groundwater flow on lake-talik evolution, Yukon Flats, Alaska (USA) Issue Title: Hydrogeology of Cold Regions In cold regions, hydrologic systems possess seasonal and perennial ice-free zones (taliks) within areas of permafrost that control and are enhanced by groundwater flow. Simulation of talik development that follows lake formation in watersheds modeled after those in the Yukon Flats of interior Alaska (USA) provides insight on the coupled interaction between groundwater flow and ice distribution. The SUTRA groundwater simulator with freeze-thaw physics is used to examine the effect of climate, lake size, and lake-groundwater relations on talik formation. Considering a range of these factors, simulated times for a through-going sub-lake talik to form through 90 m of permafrost... Categories: Data, Publication; Types: Citation, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: Modeling, Monitoring 3-Improve Permafrost Mapping, and Monitoring Improved Understanding of Permafrost Controls on Hydrology in Interior Alaska by Integration of Ground-Based Geophysical Permafrost Characterization and Numerical Modeling. Final Report Categories: Publication; Types: Citation; Tags: M3-Improve Permafrost Mapping, Modeling, and Monitoring Extending Airborne Electromagnetic Surveys for Regional Active Layer and Permafrost Mapping with Remote Sensing and Ancillary Data, Yukon Flats Ecoregion, Central Alaska Machine-learning regression tree models were used to extrapolate airborne electromagnetic resistivity data collected along flight lines in the Yukon Flats Ecoregion, central Alaska, for regional mapping of permafrost. This method of extrapolation (r?=?0.86) used subsurface resistivity, Landsat Thematic Mapper (TM) at-sensor reflectance, thermal, TM-derived spectral indices, digital elevation models and other relevant spatial data to estimate near-surface (0?2.6-m depth) resistivity at 30-m resolution. A piecewise regression model (r?=?0.82) and a presence/absence decision tree classification (accuracy of 87%) were used to estimate active-layer thickness (ALT) (< 101?cm) and the probability of near-surface (up to... Categories: Publication; Types: Citation; Tags: Baseline 1-High Resolution Landcover Imaging, Modeling, Monitoring 3-Improve Permafrost Mapping, and Monitoring Effect of permafrost thaw on the dynamics of lakes recharged by ice-jam floods: case study of Yukon flats, Alaska Categories: Publication; Types: Citation; Tags: M3-Improve Permafrost Mapping, Modeling, and Monitoring Improved Understanding of Permafrost Controls on Hydrology in Interior Alaska by Integration of Ground-Based Geophysical Permafrost Characterization and Numerical Modeling. Final Report Categories: Publication; Types: Citation; Tags: M3-Improve Permafrost Mapping, Modeling, and Monitoring Impacts of climate, lake size, and supra- and sub-permafrost groundwater flow on lake-talik evolution, Yukon Flats, Alaska (USA) Issue Title: Hydrogeology of Cold Regions In cold regions, hydrologic systems possess seasonal and perennial ice-free zones (taliks) within areas of permafrost that control and are enhanced by groundwater flow. Simulation of talik development that follows lake formation in watersheds modeled after those in the Yukon Flats of interior Alaska (USA) provides insight on the coupled interaction between groundwater flow and ice distribution. The SUTRA groundwater simulator with freeze-thaw physics is used to examine the effect of climate, lake size, and lake-groundwater relations on talik formation. Considering a range of these factors, simulated times for a through-going sub-lake talik to form through 90 m of permafrost... Categories: Publication; Types: Citation; Tags: Modeling, Monitoring 3-Improve Permafrost Mapping, and Monitoring Focused Ground-Water Recharge in the Amargosa Desert Basin The Amargosa River is an approximately 300-kilometer long regional drainage connecting the northern highlands on the Nevada Test Site in Nye County, Nev., to the floor of Death Valley in Inyo County, Calif. Streamflow analysis indicates that the Amargosa Desert portion of the river is dry more than 98 percent of the time. Infiltration losses during ephemeral flows of the Amargosa River and Fortymile Wash provide the main sources of ground-water recharge on the desert-basin floor. The primary use of ground water is for irrigated agriculture. The current study examined ground-water recharge from ephemeral flows in the Amargosa River by using streamflow data and environmental tracers. The USGS streamflow-gaging station... Categories: Publication; Types: Citation Trends in streamflow in the Yukon River Basin from 1944 to 2005 and the influence of the Pacific Decadal Oscillation Categories: Publication; Types: Citation; Tags: Monitoring 2-Standardized Stream and Lake Information Airborne electromagnetic imaging of discontinuous permafrost The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering 1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past 4 million years and the configuration of permafrost to depths of 100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the... Categories: Publication; Types: Citation; Tags: B1-High Resolution Land Cover Imaging, M3-Improve Permafrost Mapping, Modeling, and Monitoring Response to Comment on "A Reservoir of Nitrate Beneath Desert Soils" Categories: Publication; Types: Citation Airborne electromagnetic imaging of discontinuous permafrost The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering 1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past 4 million years and the configuration of permafrost to depths of 100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the... Categories: Publication; Types: Citation; Tags: B1-High Resolution Land Cover Imaging, M3-Improve Permafrost Mapping, Modeling, and Monitoring 1 2 3 »