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Articles 1141 - 1170 of 1402

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Renewing The Conservation Commitment, Frank W. Davis, Dale D. Goble, J. Michael Scott Jan 2006

Renewing The Conservation Commitment, Frank W. Davis, Dale D. Goble, J. Michael Scott

United States Geological Survey: Staff Publications

As we write this in early 2005 there are several ESA-related pieces of legislation pending before Congress. Most of the proposed legislation is championed by Republican leaders from western states, who promise to strengthen the use of science or ensure fairer treatment of private landowners. Ir has become a perennial drama on the American political stage: "conservatives" rally to rein in a law that they believe has reached too far and "conservationists" mobilize ro defend the law that they believe offers the best ho pe for protecting biodiversity from relentless economic exploitation. There is much posturing, finger pointing, and, ultimately, …


Introduction To "The Endangered Species Act At Thirty, Volume 2", Frank W. Davis, J. Michael Scott, Dale D. Goble Jan 2006

Introduction To "The Endangered Species Act At Thirty, Volume 2", Frank W. Davis, J. Michael Scott, Dale D. Goble

United States Geological Survey: Staff Publications

More than thirty years after its passage, the Endangered Species Act (ESA) of 1973 continues to be a corners tone of U.S. biodiversity policy and among our most powerful environmentallaws. The ESA set the nation's biodiversity conservation policy on a path that emphasized species-based conservation and triggered action only when a species faced imminent extinction. However, promoting recovery has proven more challenging than the original designers of the law anticipated. The number of listed species has mushroomed from 78 in 1973 to 1,267 in 2005, while in that time only 13 species have recovered sufficiently to be removed from the …


Introduction To "The Endangered Species Act At Thirty, Volume 1", J. Michael Scott, Dale D. Goble, Frank W. Davis Jan 2006

Introduction To "The Endangered Species Act At Thirty, Volume 1", J. Michael Scott, Dale D. Goble, Frank W. Davis

United States Geological Survey: Staff Publications

This book examines one legislative effoft to resolve the dilemma, the Endangered Speeies Aet of 1973 (ESA 1973). The ESA was an idealistic and perhaps naive attempt to preserve humanity by preserving other species in the ecological support system that makes life possible. In the words of the House report accompanying the bill:

A certain humility, and a sense of urgency seem indicated .... One might analogize the case to one in which one copy of all the books ever printed were gathered together in one huge building. The position in which we find ourselves today is that of custodians …


By The Numbers, J. Michael Scott, Dale D. Goble, Leona K. Svancara, Anna Pidgorna Jan 2006

By The Numbers, J. Michael Scott, Dale D. Goble, Leona K. Svancara, Anna Pidgorna

United States Geological Survey: Staff Publications

The current endangered species list has its administrative beginnings in 1964 when the Department of the Interior's Committee on Rare and Endangered Wildlife Species published a preliminary list of 62 species at risk of extinction (Goble, forthcoming). Following the enactment of the Endangered Species Preservation Act of 1966 (ESPA), the secretary of the interior in 1967 published the first official list of 78 "native fish and wildlife threatened with extinction" (ESPA sec. l(c); U.S. Department of the Interior 1967; Wilcove and McMillan, this volume). By the time the Endangered Species Act (ESA) was adopted in 1973, there were 392 species …


Breeding Biology And Success Of A Reintroduced Population Of The Critically Endangered Puaiohi (Myadestes Palmeri), Erik J. Tweed, Jeffrey T. Foster, Bethany L. Woodworth, William B. Monahan, Jherime L. Kellerman, Alan Lieberman Jan 2006

Breeding Biology And Success Of A Reintroduced Population Of The Critically Endangered Puaiohi (Myadestes Palmeri), Erik J. Tweed, Jeffrey T. Foster, Bethany L. Woodworth, William B. Monahan, Jherime L. Kellerman, Alan Lieberman

United States Geological Survey: Staff Publications

The ultimate success of reintroduction programs for endangered species depends on the ability of reintroduced animals to breed in the wild. We studied the nesting success and breeding biology of a reintroduced population of Puaiohi (Myadestes palmeri) on the island of Kaua‛i, Hawaii. Thirty-four captive-bred Puaiohi were released into the Alaka‛i Swamp in 1999–2001 and monitored using radiotelemetry. Ten females and two males paired with wild and other released birds, including one polygynous trio. From March to September, 31 nests were built. Mean clutch size was 2.0 eggs, daily nest survival was 0.97 ± 0.01 (mean ± SE) …


Reply To The Discussion By F. Lagroix And S.K. Banerjee Of “Geochemical Evidence For The Origin Of Late Quaternary Loess In Central Alaska”, Daniel R. Muhs, James R. Budahn Jan 2006

Reply To The Discussion By F. Lagroix And S.K. Banerjee Of “Geochemical Evidence For The Origin Of Late Quaternary Loess In Central Alaska”, Daniel R. Muhs, James R. Budahn

United States Geological Survey: Staff Publications

We thank F. Lagroix and S.K. Banerjee (2006) for their Muhs and Budahn 1895 interest in our recent paper and welcome this opportunity to clarify our thoughts on the issues they raise. ...

The loess deposits of central Alaska contain a long and detailed record of sedimentation and soil formation. However, we are convinced that this history is a complex one and, therefore, we again thank Lagroix and Banerjee (2006) for the opportunity to articulate some additional thoughts on the geologic record here. We applaud the use of new methods, such as those of Lagroix and Banerjee (2002, 2004), in …


Nonlinear Dynamics In Ecosystem Response To Climatic Change: Case Studies And Policy Implications, Virginia R. Burkett, Douglas A. Wilcox, Wilcox Stottlemyer, Wylie Barrow, Dan Fagre, Jill Baron, Jeff Price, Jennifer L. Nielsen, Craig D. Allen, David L. Peterson, Greg Ruggerone, Thomas Doyle Sep 2005

Nonlinear Dynamics In Ecosystem Response To Climatic Change: Case Studies And Policy Implications, Virginia R. Burkett, Douglas A. Wilcox, Wilcox Stottlemyer, Wylie Barrow, Dan Fagre, Jill Baron, Jeff Price, Jennifer L. Nielsen, Craig D. Allen, David L. Peterson, Greg Ruggerone, Thomas Doyle

United States Geological Survey: Staff Publications

Many biological, hydrological, and geological processes are interactively linked in ecosystems. These ecological phenomena normally vary within bounded ranges, but rapid, nonlinear changes to markedly different conditions can be triggered by even small differences if threshold values are exceeded. Intrinsic and extrinsic ecological thresholds can lead to effects that cascade among systems, precluding accurate modeling and prediction of system response to climate change. Ten case studies from North America illustrate how changes in climate can lead to rapid, threshold-type responses within ecological communities; the case studies also highlight the role of human activities that alter the rate or direction of …


Patterns Of Fish Use And Piscivore Abundance Within A Reconnected Saltmarsh Impoundment In The Northern Indian River Lagoon, Florida, Philip W. Stevens, Clay L. Montague, Kenneth J. Sulak Apr 2005

Patterns Of Fish Use And Piscivore Abundance Within A Reconnected Saltmarsh Impoundment In The Northern Indian River Lagoon, Florida, Philip W. Stevens, Clay L. Montague, Kenneth J. Sulak

United States Geological Survey: Staff Publications

Nearly all saltmarshes in east-central, Florida were impounded for mosquito control during the 1960s. The majority of these marshes have since been reconnected to the estuary by culverts, providing an opportunity to effectively measure exchange of aquatic organisms. A multi-gear approach was used monthly to simultaneously estimate fish standing stock (cast net), fish exchange with the estuary (culvert traps), and piscivore abundance (gill nets and bird counts) to document patterns of fish use in a reconnected saltmarsh impoundment. Changes in saltmarsh fish abundance, and exchange of fish with the estuary reflected the seasonal pattern of marsh flooding in the northern …


Evidence Of Holocene Climate Change In A Nebraska Sandhills Wetland, Barbara Nicholson, James B. Swinehart Apr 2005

Evidence Of Holocene Climate Change In A Nebraska Sandhills Wetland, Barbara Nicholson, James B. Swinehart

Great Plains Research: A Journal of Natural and Social Sciences (through 2013)

The Nebraska Sandhills consist of 50,000 km2 of dunes, currently stabilized by vegetation. Radiocarbon dates of paleosols, blocked paleovalleys, and sand beds found in interdunal wetlands suggest that the Holocene had significant periods of dune reactivation. A paleoecological investigation was conducted in Jumbo Valley, NE, in an interdunal wetland known to contain sand layers interbedded with peat. The sedimentary record in two cores is continuous, except for some loss due to surficial burns. Macrofossils indicate that the late Pleistocene was cool and wet, with current vegetation establishing around 12,000 years ago. Sand and bulk density profiles reveal significant periods …


Use Of Tracers And Isotopes To Evaluate Vulnerability Of Water In Domestic Wells To Septic Waste, Ingrid M. Verstraeten, Gregory S. Fetterman, Michael T. Meyer, Thomas D. Bullen, Sonja Sebree Apr 2005

Use Of Tracers And Isotopes To Evaluate Vulnerability Of Water In Domestic Wells To Septic Waste, Ingrid M. Verstraeten, Gregory S. Fetterman, Michael T. Meyer, Thomas D. Bullen, Sonja Sebree

United States Geological Survey: Staff Publications

In Nebraska, a large number (>200) of shallow sand-point and cased wells completed in coarse alluvial sediments along rivers and lakes still are used to obtain drinking water for human consumption, even though construction of sand-point wells for consumptive uses has been banned since 1987. The quality of water from shallow domestic wells potentially vulnerable to seepage from septic systems was evaluated by analyzing for the presence of tracers and multiple isotopes. Samples were collected from 26 sand-point and perforated, cased domestic wells and were analyzed for bacteria, coliphages, nitrogen species, nitrogen and boron isotopes, dissolved organic carbon (DOC), …


The Benthic Community Of The Eastern Us Continental Shelf: A Literature Synopsis Of Benthic Faunal Resources, R. Allen Brooks, Carla N. Purdy, Susan S. Bell, Kenneth J. Sulak Mar 2005

The Benthic Community Of The Eastern Us Continental Shelf: A Literature Synopsis Of Benthic Faunal Resources, R. Allen Brooks, Carla N. Purdy, Susan S. Bell, Kenneth J. Sulak

United States Geological Survey: Staff Publications

The existing scientific literature on offshore benthic assemblages (OBA) residing along the US East and Gulf of Mexico continental shelf was reviewed. Identification was made of any associations between the dominant OBA and particular sediment types and/or bathymetry. Of special interest was the evaluation of reported effects of sand dredge/mining activities on the dominant OBA and recognition of data deficiencies. One hundred and twenty-two references were selected and classified as to type of study with pertinent results extracted. Polychaetes were predominantly cited as the principal infaunal taxa present in studies from both the Gulf of Mexico and US Atlantic coast. …


Women In Oceanography: Women Of The Academy And The Sea, Suzanne O'Connell, Mary Anne Holmes Mar 2005

Women In Oceanography: Women Of The Academy And The Sea, Suzanne O'Connell, Mary Anne Holmes

Department of Earth and Atmospheric Sciences: Faculty Publications

Women have played an active role in all areas of oceanography. Defining the number of women oceanographers is not an easy task because the discipline is so broad and the boundaries between subdisciplines are not always distinct.


Auditory Brainstem Responses In The Eastern Screech Owl: An Estimate Of Auditory Thresholds, Elizabeth F. Brittan-Powell, Bernard Lohr, Dana L. Hahn, Robert J. Dooling Jan 2005

Auditory Brainstem Responses In The Eastern Screech Owl: An Estimate Of Auditory Thresholds, Elizabeth F. Brittan-Powell, Bernard Lohr, Dana L. Hahn, Robert J. Dooling

United States Geological Survey: Staff Publications

The auditory brainstem response (ABR), a measure of neural synchrony, was used to estimate auditory sensitivity in the eastern screech owl (Megascops asio). The typical screech owl ABR waveform showed two to three prominent peaks occurring within 5 ms of stimulus onset. As sound pressure levels increased, the ABR peak amplitude increased and latency decreased. With an increasing stimulus presentation rate, ABR peak amplitude decreased and latency increased. Generally, changes in the ABR waveform to stimulus intensity and repetition rate are consistent with the pattern found in several avian families. The ABR audiogram shows that screech owls hear best between …


Multiple-Year Droughts In Nebraska, Michael J. Hayes, Cody L. Knutson, Q. Steven Hu Jan 2005

Multiple-Year Droughts In Nebraska, Michael J. Hayes, Cody L. Knutson, Q. Steven Hu

National Drought Mitigation Center: Faculty Publications

Most people understand that droughts have had a major impact on Nebraska in the past. Yet, many Nebraskans continue to be surprised when drought occurs. It is important to remember that droughts, including multiple-year droughts, are a normal part of Nebraska’s climate. This NebGuide discusses the history of drought in Nebraska, and aims to help Nebraskans better understand the range of climatic variability when they plan for drought.


Drought Preparedness Planning: Building Institutional Capacity, Donald A. Wilhite, Michael Hayes, Cody L. Knutson Jan 2005

Drought Preparedness Planning: Building Institutional Capacity, Donald A. Wilhite, Michael Hayes, Cody L. Knutson

National Drought Mitigation Center: Faculty Publications

Past attempts to manage drought and its impacts through a reactive, crisis management approach have been ineffective, poorly coordinated, and untimely, as illustrated by the hydro- illogical cycle in Figure 1. The crisis management approach has been followed in both developed and developing countries. Because of the ineffectiveness of this approach, greater interest has evolved in recent years in the adoption of a more proactive risk-based management approach in some countries (see Chapter 6). Other countries are striving to obtain a higher level of preparedness through development of national action programs that are part of the United Nations Convention to …


A New Approach For Predicting Drought-Related Vegetation Stress: Integrating Satellite, Climate, And Biophysical Data Over The U.S. Central Plains, Tsegaue Tadesse, Jesslyn F. Brown, Michael Hayes Jan 2005

A New Approach For Predicting Drought-Related Vegetation Stress: Integrating Satellite, Climate, And Biophysical Data Over The U.S. Central Plains, Tsegaue Tadesse, Jesslyn F. Brown, Michael Hayes

National Drought Mitigation Center: Faculty Publications

Droughts are normal climate episodes, yet they are among the most expensive natural disasters in the world. Knowledge about the timing, severity, and pattern of droughts on the landscape can be incorporated into effective planning and decisionmaking. In this study, we present a data mining approach to modeling vegetation stress due to drought and mapping its spatial extent during the growing season. Rule-based regression tree models were generated that identify relationships between satellite-derived vegetation conditions, climatic drought indices, and biophysical data, including land-cover type, available soil water capacity, percent of irrigated farm land, and ecological type. The data mining method …


The Composition Of Coexisting Jarosite-Group Minerals And Water From The Richmond Mine, Iron Mountain, California, Heather E. Jamieson, Clare Robinson, Charles N. Alpers, D. Kirk Nordstrom, Alexei Poustovetov, Heather A. Lowers Jan 2005

The Composition Of Coexisting Jarosite-Group Minerals And Water From The Richmond Mine, Iron Mountain, California, Heather E. Jamieson, Clare Robinson, Charles N. Alpers, D. Kirk Nordstrom, Alexei Poustovetov, Heather A. Lowers

United States Geological Survey: Staff Publications

Jarosite-group minerals accumulate in the form of stalactites and fine-grained mud on massive pyrite in the D drift of the Richmond mine, Iron Mountain, California. Water samples were collected by placing beakers under the dripping stalactites and by extracting pore water from the mud using a centrifuge. The water is rich in Fe3+ and SO42–, with a pH of approximately 2.1, which is significantly higher than the extremely acidic waters found elsewhere in the mine. Electron-microprobe analysis and X-ray mapping indicate that the small crystals (<10 > μm in diameter) are compositionally zoned with respect to Na …


Taxonomic Relationships Among Phenacomys Voles As Inferred By Cytochrome B, M. Renee Bellinger, Susan M. Haig, Eric D. Forsman, Thomas D. Mullins Jan 2005

Taxonomic Relationships Among Phenacomys Voles As Inferred By Cytochrome B, M. Renee Bellinger, Susan M. Haig, Eric D. Forsman, Thomas D. Mullins

United States Geological Survey: Staff Publications

Taxonomic relationships among red tree voles (Phenacomys longicaudus longicaudus, P. l. silvicola), the Sonoma tree vole (P. pomo), the white-footed vole (P. albipes), and the heather vole (P. intermedius) were examined using 664 base pairs of the mitochondrial cytochrome b gene. Results indicate specific differences among red tree voles, Sonoma tree voles, white-footed voles, and heather voles, but no clear difference between the 2 Oregon subspecies of red tree voles (P. l. longicaudus and P. l. silvicola). Our data further indicated a close relationship between tree voles and albipes, …


Comparison Of Individual And Pooled Sampling Methods For Detecting Bacterial Pathogens Of Fish, Sonia Mumford, Chris Patterson, Joy Evered, Ray Brunson, Jay Levine, Jim Winton Jan 2005

Comparison Of Individual And Pooled Sampling Methods For Detecting Bacterial Pathogens Of Fish, Sonia Mumford, Chris Patterson, Joy Evered, Ray Brunson, Jay Levine, Jim Winton

United States Geological Survey: Staff Publications

Examination of finfish populations for viral and bacterial pathogens is an important component of fish disease control programs worldwide. Two methods are commonly used for collecting tissue samples for bacteriological culture, the currently accepted standards for detection of bacterial fish pathogens. The method specified in the Office International des Epizooties Manual of Diagnostic Tests for Aquatic Animals permits combining renal and splenic tissues from as many as 5 fish into pooled samples. The American Fisheries Society (AFS) Blue Book/US Fish and Wildlife Service (USFWS) Inspection Manual specifies the use of a bacteriological loop for collecting samples from the kidney of …


Discovering Associations Between Climatic And Oceanic Parameters To Monitor Drought In Nebraska Using Data-Mining Techniques, Tsegaye Tadesse, Donald A. Wilhite, Michael J. Hayes, Steve Goddard Jan 2005

Discovering Associations Between Climatic And Oceanic Parameters To Monitor Drought In Nebraska Using Data-Mining Techniques, Tsegaye Tadesse, Donald A. Wilhite, Michael J. Hayes, Steve Goddard

National Drought Mitigation Center: Faculty Publications

Drought is a complex natural hazard that is best characterized by multiple climatological and hydrological parameters. Improving our understanding of the relationships between these parameters is necessary to reduce the impacts of drought. Data mining is a recently developed technique that can be used to interact with large databases and assist in the discovery of associations between drought and oceanic data by extracting information from massive and multiple data archives. In this study, a new data-mining algorithm [i.e., Minimal Occurrences With Constraints and Time Lags (MOWCATL)] has been used to identify the relationships between oceanic parameters and drought indices. Rather …


Auditory Brainstem Responses In The Eastern Screech Owl: An Estimate Of Auditory Thresholds, Elizabeth F. Brittan-Powell, Bernard Lohr, D. Caldwell Hahn, Robert J. Dooling Jan 2005

Auditory Brainstem Responses In The Eastern Screech Owl: An Estimate Of Auditory Thresholds, Elizabeth F. Brittan-Powell, Bernard Lohr, D. Caldwell Hahn, Robert J. Dooling

United States Geological Survey: Staff Publications

The auditory brainstem response (ABR), a measure of neural synchrony, was used to estimate auditory sensitivity in the eastern screech owl (Megascops asio). The typical screech owl ABR waveform showed two to three prominent peaks occurring within 5 ms of stimulus onset. As sound pressure levels increased, the ABR peak amplitude increased and latency decreased. With an increasing stimulus presentation rate, ABR peak amplitude decreased and latency increased. Generally, changes in the ABR waveform to stimulus intensity and repetition rate are consistent with the pattern found in several avian families. The ABR audiogram shows that screech owls hear best between …


High Dispersal In A Frog Species Suggest That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf Jan 2005

High Dispersal In A Frog Species Suggest That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf

United States Geological Survey: Staff Publications

Global losses of amphibian populations are a major conservation concern and have generated substantial debate over their causes. Habitat fragmentation is considered one important cause of amphibian decline. However, if fragmentation is to be invoked as a mechanism of amphibian decline, it must first be established that dispersal is prevalent among contiguous amphibian populations using formal movement estimators. In contrast, if dispersal is naturally low in amphibians, fragmentation can be disregarded as a cause of amphibian declines and conservation efforts can be focused elsewhere. We examined dispersal rates in Columbia spotted frogs (Rana luteiventris) using capture– recapture analysis …


Population Structure Of Columbia Spotted Frogs (Rana Luteiventris) Is Strongly Affected By The Landscape, W. Chris Funk, Michael S. Blouin, Paul Stephen Corn, Bryce A. Maxell, David S. Pilliod, Stephen Amish, Fred W. Allendorf Jan 2005

Population Structure Of Columbia Spotted Frogs (Rana Luteiventris) Is Strongly Affected By The Landscape, W. Chris Funk, Michael S. Blouin, Paul Stephen Corn, Bryce A. Maxell, David S. Pilliod, Stephen Amish, Fred W. Allendorf

United States Geological Survey: Staff Publications

Landscape features such as mountains, rivers, and ecological gradients may strongly affect patterns of dispersal and gene flow among populations and thereby shape population dynamics and evolutionary trajectories. The landscape may have a particularly strong effect on patterns of dispersal and gene flow in amphibians because amphibians are thought to have poor dispersal abilities. We examined genetic variation at six microsatellite loci in Columbia spotted frogs (Rana luteiventris) from 28 breeding ponds in western Montana and Idaho, USA, in order to investigate the effects of landscape structure on patterns of gene flow. We were particularly interested in addressing …


Late-Holocene Flooding And Drought In The Northern Great Plains, Usa, Reconstructed From Tree Rings, Lake Sediments And Ancient Shorelines, M. D. Shapley, W. C. Johnson, D. R. Engstrom, W. R. Osterkamp Jan 2005

Late-Holocene Flooding And Drought In The Northern Great Plains, Usa, Reconstructed From Tree Rings, Lake Sediments And Ancient Shorelines, M. D. Shapley, W. C. Johnson, D. R. Engstrom, W. R. Osterkamp

United States Geological Survey: Staff Publications

During the AD 1990s the Waubay Lakes complex in eastern South Dakota experienced historically unprecedented high water levels. Property damage from this flooding led to an examination of the occurrence of past pluvial episodes and their relation to climate. A lOOO-year hydroclimate reconstruction was developed from local bur oak (Quercus macrocarpa) tree-ring records and lake-sediment cores. Analysis of lake shoreline and drainage features provides late-Quaternary geomorphic context for this high-resolution record. Tree-ring width and shell geochemistry of the ostracode Candona rawsoni show marked coherence, indicating synchronous responses to moisture balance in vegetation and lake salinity; geomorphic evidence …


A Watershed-Based Classification System For Lakes In Agriculturally-Dominated Ecosystems: A Case Study Of Nebraska Reservoirs, Henry N. N. Bulley Dec 2004

A Watershed-Based Classification System For Lakes In Agriculturally-Dominated Ecosystems: A Case Study Of Nebraska Reservoirs, Henry N. N. Bulley

Department of Geography: Dissertations, Theses, and Student Research

In recent decades substantial progress has been made in improving the quality of surface waters in the United States (Hawkins et al., 2000; EPA, 2000; EPA, 2001); nevertheless, much work remains to be done in assessing the state of impairment of lake waters. Impairment implies that the existing water quality of a lake, as measured by selected criteria (e.g., nitrogen, phosphorus, chlorophyll-a, Secchi depth), exceeds a threshold value or standard that presumably reflects optimal attainable lake water quality conditions (or "reference" conditions) (Hughes, 1995; EPA, 2000; EPA, 2001). Such impaired waters are not suitable for designated uses such as drinking, …


A Recommendation For An Enhanced Fujita Scale (Ef-Scale) Jun 2004

A Recommendation For An Enhanced Fujita Scale (Ef-Scale)

United States Department of Commerce: Staff Publications

Background

National Weather Service (NWS) personnel who are responsible for rating tornadoes have expressed frustrations in applying the Fujita Scale in a consistent and accurate manner. Weak links in a structural system or a slow-moving storm sometimes lead to an overrating of a tornado event. Several technical articles suggest that wind speeds associated with some descriptions of damage are too high. For example, a 260 mph wind speed is not required to completely destroy a well constructed house and blow away the debris. The damage occurs at significantly lower wind speeds. Minor et al. (1977) and Phan and Simiu (2003) …


Ogallala Aquifer, Robert F. Diffendal Jr. Jan 2004

Ogallala Aquifer, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

The Ogallala Aquifer, or High Plains Aquifer, is a porous body of complex sediments and sedimentary rock formations that conducts groundwater and yields significant quantities of water to wells and springs. The principal sediments and rocks of the aquifer range in age from 33 million years old to sediments being deposited today, but the majority is less than 12 million-years old. Much of the aquifer is composed of the Ogallala Group or Formation. The dominant sediments in the Ogallala and the other hydrogeologic units in the aquifer are riverand wind-deposited sands. The aquifer underlies about 174,000 square miles of the …


An Analysis Of Simulated Long-Term Soil Moisture Data For Three Land Uses Under Contrasting Hydroclimatic Conditions In The Northern Great Plains, Rezaul Mamood, Kenneth G. Hubbard Jan 2004

An Analysis Of Simulated Long-Term Soil Moisture Data For Three Land Uses Under Contrasting Hydroclimatic Conditions In The Northern Great Plains, Rezaul Mamood, Kenneth G. Hubbard

High Plains Regional Climate Center: Staff Publications

Soil moisture (SM) plays an important role in land surface and atmosphere interactions. It modifies energy balance near the surface and the rate of water cycling between land and atmosphere. The lack of observed SM data prohibits understanding of SM variations at climate scales under varying land uses. However, with simulation models it is possible to develop a long-term SM dataset and study these issues. In this paper a water balance model is used to provide a quantitative assessment of SM climatologies for three land uses, namely, irrigated corn, rain-fed corn, and grass, grown under three hydroclimatic regimes in Nebraska. …


An Agricultural Drought Risk-Assessment Model For Corn And Soybeans, Hong Wu, Kenneth G. Hubbard, Donald A. Wilhite Jan 2004

An Agricultural Drought Risk-Assessment Model For Corn And Soybeans, Hong Wu, Kenneth G. Hubbard, Donald A. Wilhite

National Drought Mitigation Center: Faculty Publications

Copyright © 2004 Royal Meteorological Society. Published by Wiley InterScience. Used by permis-sion.


An Operational Agricultural Drought Risk Assessment Model For Nebraska, Usa, Hong Wu, Donald A. Wilhite Jan 2004

An Operational Agricultural Drought Risk Assessment Model For Nebraska, Usa, Hong Wu, Donald A. Wilhite

National Drought Mitigation Center: Faculty Publications

Drought is a common occurrence in Nebraska and agriculture is the primary economic sector affected. Because of repeated and widespread severe drought impacts, more emphasis on drought risk management is warranted. This study develops an agricultural drought risk assessment model using multivariate techniques. The model is specific to corn and soybeans and is able to assess real-time agricultural drought risk associated with crop yield losses at critical phenological stages prior to and during the growing season. The assessment results are presented in a Geographic Information System to provide a better visualization. This model provides information in a timely manner about …