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At least 1,063 records · Page 59Linked to original sources
USGS2018

Research to improve ShakeAlert earthquake early warning products and their utility

Earthquake early warning (EEW) is the rapid detection of an earthquake and issuance of an alert or notification to people and vulnerable systems likely to experience potentially damaging ground shaking. The level of ground shaking that is considered damaging is defined by the specific application; for example, manufacturing equipment may experience damage at a lower intensity ground shaking than would cause damage to a building. Along the West Coast of the United States, the warning times for ground shaking could range as high as tens of seconds for moderate levels of ground shaking, or potentially longer, if a lower ground-shaking threshold is used to issue alerts. However, it is not always possible to provide advance warning of ground shaking, particularly for locations close to an earthquake that are most likely to experience very strong ground shaking. EEW alerts may be useful to individuals who can use a few seconds to move to a safe zone and to electromechanical systems that can take automatic actions to reduce damage and injuries. An EEW system, ShakeAlert, has been under development in the United States since 2006. Federal and State governments, as well as the private sector, are now investing in the ShakeAlert prototype system that will, when completed, become an operational public system for the West Coast of the United States. While the current prototype is delivering alerts to test users, improvements to the accuracy, timeliness, and utility of the alerts are needed. For this reason, it is essential that the ShakeAlert system be continuously improved through targeted research, involving not only the current ShakeAlert partner organizations, but also the broader scientific, engineering, and emergencyresponse communities. To this end, this report describes the opportunities for improvement that can be addressed through research and development over the next 5 years. Our recommendations are organized into four areas: (1) understand EEW capabilities and user needs, (2) make alerts as fast and accurate as possible, (3) ensure reliability when it counts, and (4) explore the use of new instrumentation. The first challenge is to understand EEW capabilities and user needs. EEW must deliver actionable information to people and to automated systems to mitigate short- and longterm impacts of damaging ground shaking, so development of EEW must be motivated by the needs of users. Within this challenge, we must study the technical capabilities and limitations of EEW in general, and the ShakeAlert system specifically. This includes development of performance metrics that assess the timeliness and accuracy of alerts to understand the value and utility of the ShakeAlert EEW product(s) for various user groups, including different industry sectors, emergency-management agencies, and the public. Research is needed to define the alerting choices that maximize the utility of the system for users and to determine what the available communication pathways are for providing timely alert information. Additionally, we engage users to assess how alerts will be used by different sectors to mitigate losses and to inform EEW product design. Further, social-science research is needed to develop alert messaging, including what relevant prior and follow-up information are required, to ensure effective use of alerts. The second challenge is to make alerts as fast and as accurate as possible. The timeliness and accuracy of an EEW alert is important because it will set in motion a series of actions and downstream products. An EEW alert will trigger notification across emergency-alert systems and across multiple communication channels to populations in impacted regions. The EEW alert region may grow as the earthquake fault-rupture length increases, and the EEW system’s characterization of it, evolves. We must continue research into new or improved seismic and geodetic waveform-processing methods necessary to rapidly characterize the expected ground shaking and associated uncertainties. It is important to thoroughly evaluate whether new methods improve alerts through more accurate ground-motion estimates and (or) reduced latencies (that is, longer warning times). New methods could include tracking the extent of a large rupture in real time (known as finite-fault algorithms) and ground-motionbased EEW algorithms. Additionally, ground motion predictions could be optimized for each earthquake as the earthquake fault rupture progresses by using, for example, event terms to shift ground-motion curves for more (or less) energetic ruptures. The third challenge is to ensure reliability when it counts. This challenge requires us to explore approaches that assess the expected performance of ShakeAlert across the range of earthquake magnitudes, locations, and depths that may occur within the alerting region. Large, damaging earthquakes and their associated aftershock sequences matter most for hazard and for EEW, but these large-earthquake sequences occur infrequently. We expect ShakeAlert to respond robustly to these large-earthquake sequences despite potentially long periods of relative seismic quiescence in the intervening years, and in spite of inevitable communication challenges that arise during and after a large earthquake. We must develop methods to utilize the broadest available datasets to test EEW performance, including ground-motion data recorded in other parts of the world. The observational period for large, damaging earthquakes in any particular region has been short in comparison to estimated large-earthquake recurrence times. Ground-motion records for very large, damaging western United States events and major aftershock sequences do not yet exist, nor do data exist for all potential sources of noise and spurious signals that ShakeAlert must be “tuned” to reject. In addition, robust synthetic data could provide the flexibility to test a wider range of earthquake magnitude, tectonic-setting, and noise scenarios than are covered by existing observational data. Synthetic ground-motion data must be thoroughly vetted against records of smaller magnitude earthquakes to ensure that they accurately capture both the onset and the amplitude of the ground shaking. The final challenge is to explore the use of new instrumentation. The development of EEW around the world to date has focused on the use of high-quality, scientific-grade seismic and geodetic instrumentation. The use of additional types of instrumentation or information may also improve EEW products by filling gaps in sensor coverage in countries that already have dense seismic networks or enable EEW in countries without such networks. We must keep up with these developments and continuously assess their value in supplementing existing EEW systems, such as ShakeAlert, or enabling EEW where such systems do not exist. Such developments include low-cost instrumentation with microelectromechanical system (MEMS) sensors and global positioning system (GPS)/global navigation satellite system (GNSS) antennas embedded in low-cost consumer electronics, sea-floor seismometers, geodetic instrumentation deployed along the Cascadia and Alaska megathrust margins of western North America, and borehole strainmeters that are already deployed across the region.

Open-File Report↗
USGS2015

Indian National Gas Hydrate Program Expedition 01 report

Gas hydrate is a naturally occurring “ice-like” combination of natural gas and water that has the potential to serve as an immense resource of natural gas from the world’s oceans and polar regions. However, gas-hydrate recovery is both a scientific and a technical challenge and much remains to be learned about the geologic, engineering, and economic factors controlling the ultimate energy resource potential of gas hydrate. The amount of natural gas contained in the world’s gas-hydrate accumulations is enormous, but these estimates are speculative and range over three orders of magnitude from about 2,800 to 8,000,000 trillion cubic meters of gas. By comparison, conventional natural gas accumulations (reserves and undiscovered, technically recoverable resources) for the world are estimated at approximately 440 trillion cubic meters. Gas recovery from gas hydrate is hindered because the gas is in a solid form and because gas hydrate commonly occurs in remote Arctic and deep marine environments. Proposed methods of gas recovery from gas hydrate generally deal with disassociating or “melting” in situ gas hydrate by heating the reservoir beyond the temperature of gas-hydrate formation, or decreasing the reservoir pressure below hydrate equilibrium. The pace of energy-related gas hydrate assessment projects has accelerated over the past several years. The Indian National Gas Hydrate Program Expedition 01 was designed to study the gas-hydrate occurrences off the Indian Peninsula and along the Andaman convergent margin with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. During Indian National Gas Hydrate Program Expedition 01, dedicated gas-hydrate coring, drilling, and downhole logging operations were conducted from 28 April 2006 to 19 August 2006.

Krishna-Godivari Basin↗
USGS2005

Verification of sex from harvested sea otters using DNA testing

We used molecular genetic methods to determine the sex of 138 sea otters ( Enhydra lutris ) harvested from 3 regions of Alaska from 1994 to 1997, to assess the accuracy of post‐harvest field‐sexing. We also tested each of a series of factors associated with errors in field‐sexing of sea otters, including male or female bias, age‐class bias, regional bias, and bias associated with hunt characteristics. Blind control results indicated that sex was determined with 100% accuracy using polymerase chain reaction (PCR) amplification using primers that co‐amplify the zinc finger‐Y‐X gene, located on both the mammalian Y‐ and X‐chromosomes, and Testes Determining Factor (TDF), located on the mammalian Y‐chromosome. DNA‐based sexing revealed that 12.3% of the harvested sea otters were incorrectly sexed in the field, with most errors (13 of 17) occurring as males incorrectly reported as females. Thus, female harvest was overestimated. Using logistic regression analysis, we detected no statistical association of incorrect determination of sex in the field with age class, hunt region, or hunt type. The error in field‐sexing appears to be random, at least with respect to the variables evaluated in this study.

Wildlife Society Bulletin↗
USGS1999

A plan for assessing the occurrence and distribution of methyl tert-butyl ether and other volatile organic compounds in drinking water and ambient ground water in the Northeast and Mid-Atlantic regions of the United States

A plan to assess the occurrence and distribution of methyl tert-butyl ether (MTBE) and other volatile organic compounds (VOCs) in drinking water and ambient ground water in the Northeast and Mid-Atlantic regions of the United States was designed to meet two primary objectives. This study will provide the U.S. Environmental Protection Agency with information on potential human exposure to MTBE and other VOCs from drinking water. In addition, the study will further the goals of the U.S. Geological Survey's (USGS) National Water Quality Assessment Program (NAWQA) by providing additional information on the occurrence and distribution of VOCs in ambient ground water beneath a large, highly urbanized part of the Nation. The study will proceed in two phases-a drinking-water assessment (phase 1) and an ambient ground-water assessment (phase 2). The drinking-water assessment will involve compilation, review, and analysis of available water- quality and ancillary data for approximately 20 percent of the community water systems in 12 States in the Northeast and Mid-Atlantic regions. This effort will summarize the occurrence and distribution of MTBE and other VOCs in drinking water supplied by 2,110 community water systems. The ambient ground-water assessment will involve compilation, review, and analysis of data on MTBE and other VOCs from previous USGS studies in the 12-State area, including regional water-quality assessments conducted for the USGS's NAWQA, plus other available State or local datasets. These data will be related, to the extent allowed by the completeness and quality of the data, to land-use patterns, population density, and other anthropogenic and natural factors using statistical tests. The occurrence and distribution of MTBE and other VOCs in ambient ground water and, to the extent possible, drinking water in relation to such factors, will be evaluated.

Open-File Report↗
USGS2016

Changes between early development (1930–60) and recent (2005–15) groundwater-level altitudes and dissolved-solids and nitrate concentrations In and near Gaines, Terry, and Yoakum Counties, Texas

Llano Estacado Underground Water Conservation District, Sandy Land Underground Water Conservation District, and South Plains Underground Water Conservation District manage groundwater resources in a part of west Texas near the Texas-New Mexico State line. Declining groundwater levels have raised concerns about the amount of available groundwater in the study area and the potential for water-quality changes resulting from dewatering and increased vertical groundwater movement between adjacent water-bearing units. In 2014, the U.S. Geological Survey, in cooperation with Llano Estacado Underground Water Conservation District, Sandy Land Underground Water District, and South Plains Underground Water Conservation District, began a multiphase project to develop a regional conceptual model of the hydrogeologic framework and geochemistry of the Ogallala, Edwards-Trinity, and Dockum aquifers. The Ogallala aquifer is the shallowest aquifer in the study area and is the primary source of water for agriculture and municipal supply in the area. This report describes the results of the first phase of the study, during which groundwater-level-altitude and selected water-quality data from wells in and near Gaines, Terry, and Yoakum Counties were compiled and evaluated for the Ogallala, Edwards-Trinity, and Dockum aquifers. Readily available digital groundwater data for the study area (geologic, well-construction, groundwater-level-altitude, and selected water-quality data) were compiled to assess temporal and spatial changes in groundwater resources from early development (1930–60) to recent (2005–15) periods. Pertinent data were compiled from available sources for the study area and for a 5-mile buffer area around the study area to prevent gridding errors near the boundary. Geologic and well-construction data were used to determine or verify the aquifer in which each well was completed. Depending on the available data, the aquifer assignment (aquifer in which a given well was completed) was determined on the basis of the following criteria, in order of priority: (1) the screened or open interval(s) of the well, (2) the total depth of the well, or (3) the completed aquifer reported for a given well by the data source. Potentiometric-surface maps were created to depict changes in groundwater-level altitudes for the Ogallala and Edwards-Trinity aquifers. In addition to comparing groundwater-level altitudes and water quality from the early development and recent periods, hydrographs of groundwater-level altitudes were created, and changes in water quality for various periods between 1930 and 2015 were evaluated. Variance maps for each groundwater-level-altitude grid were used to evaluate the spatial data coverage and to identify areas with higher uncertainty because of spatially limited data availability for some of the aquifers. For this report, existing dissolved-solids and nitrate concentration data were compiled and assessed for evidence of spatial patterns and changes over time. These data were compiled for samples collected from wells completed in the Ogallala, Edwards-Trinity, or Dockum aquifer during the early development period (1930–60) or the recent period (2005–15); temporal and spatial variations were assessed from depictions of the measured concentration values. Dissolved-solids and nitrate concentrations measured in samples from three wells completed in the Ogallala aquifer (well identifiers 11524, 11824, and 11825) for which long-term monitoring was done for various periods between 1950 and 2015 were also compiled and analyzed. Groundwater-level altitudes of the Ogallala aquifer are generally higher in the northwestern part of the study area and lower in the southeastern part of the study area, varying by as much as 800 feet. Groundwater flow paths for the early development period generally trend from northwest to southeast across the study area. Compared to those for the early development period, local features in the potentiometric surface for the recent period are more pronounced, likely as a result of additional data coverage, increased groundwater withdrawals, and local flow paths that are more variable. For the Edwards-Trinity aquifer potentiometric-surface map of the recent period, a general northwest to southeast flow gradient was also evident, with some subtle differences compared to the early development period. The Edwards-Trinity aquifer water-level-altitude change map between the early development and recent periods indicated similar spatial trends as in the Ogallala aquifer and indicated that groundwater-level altitudes declined over a large amount of the area for which sufficient data were available for reliably mapping changes. During the recent period, median dissolved-solids concentrations of less than 1,000 milligrams per liter (mg/L) were predominantly measured in the western part of the study area, and median concentrations of more than 1,000 mg/L were predominantly measured in the eastern part of the study area. A general pattern of increasing nitrate concentrations from west to the northeast was evident in the study area. Nitrate concentrations measured in samples collected from 16 wells completed in the Ogallala aquifer for the recent period were equal to or greater than 10 mg/L, the primary drinking water standard for finished drinking water.

Texas↗
USGS2007

Coastal systems and low-lying areas

Since the IPCC Third Assessment Report (TAR), our understanding of the implications of climate change for coastal systems and low-lying areas (henceforth referred to as ‘coasts’) has increased substantially and six important policy-relevant messages have emerged. Coasts are experiencing the adverse consequences of hazards related to climate and sea level (very high confidence). Coasts are highly vulnerable to extreme events, such as storms, which impose substantial costs on coastal societies [6.2.1, 6.2.2, 6.5.2]. Annually, about 120 million people are exposed to tropical cyclone hazards, which killed 250,000 people from 1980 to 2000 [6.5.2]. Through the 20th century, global rise of sea level contributed to increased coastal inundation, erosion and ecosystem losses, but with considerable local and regional variation due to other factors [6.2.5, 6.4.1]. Late 20th century effects of rising temperature include loss of sea ice, thawing of permafrost and associated coastal retreat, and more frequent coral bleaching and mortality [6.2.5]. Coasts will be exposed to increasing risks, including coastal erosion, over coming decades due to climate change and sea-level rise (very high confidence). Anticipated climate-related changes include: an accelerated rise in sea level of up to 0.6 m or more by 2100; a further rise in sea surface temperatures by up to 3°C; an intensification of tropical and extra-tropical cyclones; larger extreme waves and storm surges; altered precipitation/run-off; and ocean acidification [6.3.2]. These phenomena will vary considerably at regional and local scales, but the impacts are virtually certain to be overwhelmingly negative [6.4, 6.5.3]. Corals are vulnerable to thermal stress and have low adaptive capacity. Increases in sea surface temperature of about 1 to 3°C are projected to result in more frequent coral bleaching events and widespread mortality, unless there is thermal adaptation or acclimatisation by corals [Box 6.1, 6.4]. Coastal wetland ecosystems, such as saltmarshes and mangroves, are especially threatened where they are sediment starved or constrained on their landward margin [6.4.1]. Degradation of coastal ecosystems, especially wetlands and coral reefs, has serious implications for the well-being of societies dependent on the coastal ecosystems for goods and services [6.4.2, 6.5.3]. ncreased flooding and the degradation of freshwater, fisheries and other resources could impact hundreds of millions of people, and socio-economic costs on coasts will escalate as a result of climate change [6.4.2, 6.5.3]. The impact of climate change on coasts is exacerbated by increasing human-induced pressures (very high confidence). Utilisation of the coast increased dramatically during the 20th century and this trend is virtually certain to continue through the 21st century. Under the SRES scenarios, the coastal population could grow from 1.2 billion people (in 1990) to 1.8 to 5.2 billion people by the 2080s, depending on assumptions about migration [6.3.1]. Increasing numbers of people and assets at risk at the coast are subject to additional stresses due to land-use and hydrological changes in catchments, including dams that reduce sediment supply to the coast [6.3.2]. Populated deltas (especially Asian megadeltas), low-lying coastal urban areas and atolls are key societal hotspots of coastal vulnerability, occurring where the stresses on natural systems coincide with low human adaptive capacity and high exposure [6.4.3]. Regionally, South, South- East and East Asia, Africa and small islands are most vulnerable [6.4.2]. Climate change therefore reinforces the desirability of managing coasts in an integrated manner [6.6.1.3]. Adaptation for the coasts of developing countries will be more challenging than for coasts of developed countries, due to constraints on adaptive capacity (high confidence). While physical exposure can significantly influence vulnerability for both human populations and natural systems, a lack of adaptive capacity is often the most important factor that creates a hotspot of human vulnerability. Adaptive capacity is largely dependent upon development status. Developing nations may have the political or societal will to protect or relocate people who live in low-lying coastal zones, but without the necessary financial and other resources/capacities, their vulnerability is much greater than that of a developed nation in an identical coastal setting. Vulnerability will also vary between developing countries, while developed countries are not insulated from the adverse consequences of extreme events [6.4.3, 6.5.2]. Adaptation costs for vulnerable coasts are much less than the costs of inaction (high confidence). Adaptation costs for climate change are much lower than damage costs without adaptation for most developed coasts, even considering only property losses and human deaths [6.6.2, 6.6.3]. As post-event impacts on coastal businesses, people, housing, public and private social institutions, natural resources, and the environment generally go unrecognised in disaster cost accounting, the full benefits of adaptation are even larger [6.5.2, 6.6.2]. Without adaptation, the high-end sea-level rise scenarios, combined with other climate changes (e.g., increased storm intensity), are as likely as not to render some islands and lowlying areas unviable by 2100, so effective adaptation is urgently required [6.6.3]. The unavoidability of sea-level rise, even in the longer-term, frequently conflicts with present-day human development patterns and trends (high confidence). Sea-level rise has substantial inertia and will continue beyond 2100 for many centuries. Irreversible breakdown of the West Antarctica and/or Greenland ice sheets, if triggered by rising temperatures, would make this long-term rise significantly larger, ultimately questioning the viability of many coastal settlements across the globe. The issue is reinforced by the increasing human use of the coastal zone. Settlement patterns also have substantial inertia, and this issue presents a challenge for long-term coastal spatial planning. Stabilisation of climate could reduce the risks of ice sheet breakdown, and reduce but Chapter 6 Coastal systems and low-lying areas 317 not stop sea-level rise due to thermal expansion [Box 6.6]. Hence, it is now more apparent than it was in the TAR that the most appropriate response to sea-level rise for coastal areas is a combination of adaptation to deal with the inevitable rise, and mitigation to limit the long-term rise to a manageable level [6.6.5, 6.7].

Book chapter↗
USGS2002

Cruise report RV Moana Wave Cruise M-1-02-GM bathymetry and acoustic backscatter of the mid and outer continental shelf, head of De Soto Canyon, northeastern Gulf of Mexico June 17, through July 9, 2002 Pensacola, FL to Pensacola, FL

The mid to outer continental shelf off Mississippi-Alabama and off northwest Florida were the focus of US Geological Survey (USGS) multibeam echosounder (MBES) mapping cruises in 2000 and 2001, respectively. These areas were mapped to investigate the extent of "deep-water reefs" first suggested by Ludwick and Walton (1957). The reefs off Mississippi and Alabama were initially described in water depths of 60 to 120 m (Ludwick and Walton, 1957) but the 2000 mapping found reef and hardgrounds to be much more extensive than previously thought (Gardner et al., 2001). The persistent trend of reef-like features along the outer shelf of Mississippi-Alabama suggested the trend might continue along the northwest Florida mid and outer shelf so a MBES-mapping effort was mounted in 2001 to test this suggestion. It is critical to determine the accurate location, geomorphology, and types of the ridges and reefs that occur in this region to understand the Quaternary history of the area and to assess their importance as benthic habitats for fisheries. The 2001 survey found a series of shelf-depth platforms with ridges (possibly reefs) constructed on their surfaces (Gardner et al., 2002). The area known as the "head of De Soto Canyon" is the large unmapped region between the 2000 and 2001 mapped areas. The head of De Soto Canyon is an outer shelf zone with a relatively steep western wall and a much gentler eastern wall. It was unknown prior to this cruise whether the reefs of the Mississippi-Alabama shelf continue eastward into the head of De Soto Canyon and connect with the ridges and reefs mapped on the northwest Florida outer shelf. The existence of carbonate-cemented latest Quaternary to Holocene sandstones along the western wall of the head of De Soto Canyon (Shipp and Hopkins, 1978; Benson et al., 1997; W.W. Schroeder, personnel comm., 2002) is of interest because of the potential benthic habitats they may represent. Precisely georeferenced high-resolution mapping of bathymetry is a fundamental first step in the study of an area suspected to be critical benthic habitats. Morphology is thought to be critical to define the distribution of dominant demersal plankton/planktivores communities. Community structure and trophodynamics of demersal fishes of the outer continental shelf of the northeastern Gulf of Mexico presently are focuses of a major USGS research project. A goal of the project is to answer questions concerning the relative roles played by morphology and surficial geology in controlling biological differentiation. Deep-water ridges, reefs, and outcrops are important because they are fish havens and key spawning sites, and are critical habitats for larval, juvenile, and economically important sport/food fishes.

Gulf of Mexico, head Of De Soto Canyon↗
USGS2018

Geology and assessment of undiscovered oil and gas resources of the Hope Basin Province, 2008

The Hope Basin, an independent petroleum province that lies mostly offshore in the southern Chukchi Sea north of the Chukotka and Seward Peninsulas and south of Wrangel Island, the Herald Arch, and the Lisburne Peninsula, is the largest in a series of postorogenic (successor) basins in the East Siberian-Chukchi Sea region and the only one with exploratory-well control and extensive seismic coverage. In spite of the seismic coverage and well data, the petroleum potential of the Hope Basin Province is poorly known. The adequacy of hydrocarbon charge, in combination with uncertainties in source-rock potential and maturation, was the greatest risk in this assessment. A single assessment unit was defined and assessed, resulting in mean estimates of undiscovered, technically recoverable resources that include ~3 million barrels of oil and 650 billion cubic feet of nonassociated gas.

Professional Paper↗
USGS1999

Stream and aquifer biology of south-central Texas — A literature review, 1973-97

This report summarizes in table format 32 aquatic vertebrate (primarily fish), 54 aquatic invertebrate, and 13 aquatic plant studies available for the area of the South-Central Texas study unit of the U.S. Geological Survey National Water-Quality Assessment. The studies, published mostly during 1973–97, pertain to the Guadalupe, San Antonio, and Nueces River Basins, the San Antonio-Nueces and Nueces-Rio Grande Coastal Basins, and the Edwards aquifer where it underlies the upper parts of the three river basins. The biology of the study-unit streams is determined mostly by the characteristics of the ecoregions they transect—the Edwards Plateau, Texas Blackland Prairies, East Central Texas Plains, Western Gulf Coastal Plain, and Southern Texas Plains. About 20 percent of the previous fish and invertebrate studies and about 75 percent of the aquatic plant surveys have centered on Comal Springs in Comal County and San Marcos Springs in Hays County. Although several important studies are available for the San Antonio region, documentation of aquatic biology for the remainder of the study unit is relatively sparse. The streams in the study unit, particularly in the Edwards Plateau, support three dominant biological groups—fish, aquatic invertebrates, and plants. Potential threats to these organisms include impoundments and flood-control projects, siltation from erosion, ground-water pumping, recreational activities, wastewater discharge, and introduction of non-native species. More than 30 non-native fish, invertebrate, and plant species have been introduced into the region. Of the 19 aquatic species Federally listed as endangered or threatened in Texas, 8 are associated with springs and spring runs in the study unit. All of the endangered species in the study unit are associated with springs and spring runs. A large number of endemic species in the study unit are associated with subterranean aquatic ecosystems, most likely a consequence of the unique proximity of the varied topographic and hydrologic conditions of the area and of the geological development of the Edwards aquifer. Ninety-one endemics, including 44 species found solely underground, are associated with the aquatic ecosystems (including springs) of the Edwards aquifer.

Texas↗
USGS2000

A field guide for the assessment of erosion, sediment transport, and deposition in incised channels of the southwestern United States

Deeply incised channels, commonly called arroyos, are a typical feature of the dry alluvium-filled valleys of the southwestern United States. Unlike many geological processes that operate over millions of years, the formation of many miles of arroyos is one that took place in a little more than a century. Most arroyos in the region began to form in the late 19th century. Because dry landscapes change so quickly, they present society with special problems. Rapid expansion of channels by headcut migration, deepening, and widening causes loss of productive agricultural and commercial lands and threatens infrastructure such as roads, bridges, and buildings. High rates of sedimentation shorten the life of reservoirs, clog culverts, and fill stream channels to the extent that they can no longer contain streamflow within their banks. This report presents an explanation of erosional and depositional processes in desert landscapes, especially those characterized by incised channels, for the use of those who use, manage, and live on such lands. The basic principles of erosion, sediment transport, and deposition are presented including the formation of sediment, the forces that erode and transport it, the forces that resist its erosion and transport, and the conditions that cause it to be deposited. The peculiarities of sedimentation processes in the Southwest include the infrequent and variable precipitation, the geological setting, and the sparseness of vegetation. A classification system for incised channels that is intended for users who do not necessarily have a background in fluvial hydrology has been developed and is presented in this report. The classification system is intended to enable a user to classify a reach of channel quickly on the basis of field observations. The system is based on the shape and condition of channels and on the sedimentation processes that are predominantly responsible for those conditions. Because those processes are controlled by environmental factors operating on the entire drainage basin, classification of channels can provide land managers and users with an understanding of what areas are likely to be most susceptible to erosion or the effects of high sedimentation rates and under what conditions they are most likely to occur.

Water-Resources Investigations Report↗
USGS2018

The 1952 Kern County, California earthquake: A case study of issues in the analysis of historical intensity data for estimation of source parameters

Seismic intensity data based on first-hand accounts of shaking give valuable insight into historical and early instrumental earthquakes. Comparing an observed intensity distribution to intensity-prediction models based on modern calibration events allows the magnitude to be estimated for many historic earthquakes. Magnitude estimates can also potentially be refined for earthquakes for which limited instrumental data are available. However, the complicated nature of macroseismic data and the methods used to collect and interpret the data introduce significant uncertainties. In this paper, we illustrate these challenges and possible solutions using the 1952 Kern County, California, earthquake as a case study. Published estimates of its magnitude vary from M W 7.2–7.5, making it possibly the second largest in California during the 20th century. We considered over 1100 first-hand reports of shaking, supplemented with other data, and inferred the magnitude in several ways using intensity prediction equations, yielding a preferred intensity magnitude M I 7.2 ± 0.2, where the uncertainty reflects our judgement. The revised intensity distribution reveals stronger shaking on the hanging wall, south of the surface expression of the White Wolf fault, than on the footwall. Characterizing the magnitude and shaking distribution of this early instrumental earthquake can help improve estimation of the seismic hazard of the region. Such reinterpreted intensities for historic earthquakes, combined with U.S. Geological Survey (USGS) Did You Feel It? data for more recent events, can be used to produce a uniform shaking dataset with which earthquake hazard map performance can be assessed.

California↗
USGS2024

An accuracy assessment of the surface reflectance product from the EMIT imaging spectrometer

The Earth surface Mineral dust source InvesTigation (EMIT) is an imaging spectrometer launched to the International Space Station in July 2022 to measure the mineral composition of Earth’s dust-producing regions. We present a systematic accuracy assessment of the EMIT surface reflectance product in two parts. First, we characterize the surface reflectance product’s overall performance using multiple independent vicarious calibration field experiments with hand-held and automated field spectrometers. We find that the EMIT surface reflectance product has a standard error of ±1.0 % in absolute reflectance units for temporally coincident observations. Discrepancies rise to ±2.7 % for spectra acquired at different dates and times of day, which we attribute mainly to changes in solar geometry. Second, we develop an error budget that explains the differences between EMIT and in-situ field spectrometer data. We find that uncertainties in spatial footprints, field spectroscopy, and the EMIT-reported measurement were sufficient to explain discrepancies in most cases. Our approach did not detect any systematic calibration or reflectance errors in the timespan considered. Together, these findings demonstrate that a space-based imaging spectrometer can acquire high-quality spectra across a wide range of observational and atmospheric conditions.

Nevada↗
USGS2007

Geophysical framework investigations influencing ground-water resources in east-central Nevada and west-central Utah, with a section on geologic and geophysical basin by basin descriptions

A geophysical investigation was undertaken as part of an effort to characterize the geologic framework influencing ground-water resources in east-central Nevada and west-central Utah. New gravity data were combined with existing aeromagnetic, drill-hole, and geologic data to help determine basin geometry, infer structural features, estimate depth to pre-Cenozoic basement rocks, and further constrain the horizontal extents of exposed and buried plutons. In addition, a three-dimensional (3D) geologic model was constructed to help illustrate the often complex geometries of individual basins and aid in assessing the connectivity of adjacent basins. In general, the thirteen major valleys within the study area have axes oriented north-south and frequently contain one or more sub-basins. These basins are often asymmetric and typically reach depths of 2 km. Analysis of gravity data helped delineate geophysical lineaments and accommodation zones. Structural complexities may further compartmentalize ground-water flow within basins and the influence of tectonics on basin sedimentation further complicates their hydrologic properties. The horizontal extent of exposed and, in particular, buried plutons was estimated over the entire study area. The location and subsurface extents of these plutons will be very important for regional water resource assessments, as these features may act as either barriers or pathways for groundwater flow. A previously identified basement gravity low strikes NW within the study area and occurs within a highly extended terrane between the Butte and Confusion synclinoria. Evidence from geophysical, geologic, and seismic reflection data suggests relatively lower density plutonic rocks may extend to moderate crustal depths and rocks of similar composition may be the source of the entire basement gravity anomaly.

Nevada, Utah↗
USGS2018

Quantifying effects of deer browsing on vegetation establishment, growth and development in large-extent overwash fans

Hurricane Sandy provided a unique opportunity to better understand the potential effects of white-tailed deer ( Odocoileus virginianus borealis ) on recovering vegetation in areas overwashed by Hurricane Sandy in the Otis Pike Fire Island High Dune Wilderness Area. White-tailed deer are the dominant herbivore on Fire Island and they are known to decrease plant diversity, limit reproduction and growth of some plant species, and facilitate growth and expansion of non-native species through selective browsing. Deer also negatively affect the federally-threatened seabeach amaranth plants along the island’s beaches. Deer impacts to forest understory and regeneration have been documented in Fire Island’s Sunken Forest for decades, though their impacts to recovering dune vegetation are less understood and could restrict the resilience and recovery of primary dunes. Through use of several vegetation assessment methods, including point intercept and paired permanent exclosures, and deer monitoring with trail cameras, we documented high variability in among-overwash species richness, vegetation cover, and local deer abundance. We observed 29 vegetation species among overwash fans between 2015 and 2016. Greater vegetation cover was observed in northern (i.e., inland) areas of all overwash fans, and greater cover and species richness were documented in fenced permanent plots than in control plots. The greatest effect of deer browsing to recovering dune vegetation was in total vegetation cover, which was significantly greater in fenced permanent plots. Any amaranth plants left open (i.e., un-exclosed) were often heavily browsed and experienced early onset mortality without reproducing. Since Hurricane Sandy, total vegetation cover in overwash fans has significantly increased each year, despite deer activity and a regional drought in 2016. While deer graze and browse vegetation in overwash fans, deer and humans trample vegetation in some overwash fans and separating effects of each is not possible from exclusion studies alone. Two overwash fans have been consistently impacted by coastal disturbances since Hurricane Sandy, further complicating their recoveries. Monitoring of dune vegetation should continue as communities transition from predominantly grasses to shrubs and forbs to assess effects of deer as palatability of vegetation improves.

New York↗
USGS1997

Parasites of lake herring ( Coregonus artedi ) from Lake Superior, with special reference to use of parasites as markers of stock structure

We examined parasites of 152 lake herring ( Coregonus artedi ) collected from three locations in Wisconsin waters of Lake Superior in 1994, four locations in Wisconsin waters in 1996, and one location in Minnesota waters in 1996 to determine; 1) the species composition and relative abundances of parasites in lake herring, 2) the differences in parasite relative abundances across locations sampled, and 3) the utility of parasite relative abundances as markers of stock structure. Parasites from 19 taxa infected lake herring collected in 1994 and 1996; Henneguya zschokkei , Chloromyxum sp., and Cyatho-cephalus truncatus were reported in fishes from Lake Superior for the first time, and Clinostomum mar-ginatum was reported in lake herring for the first time. Significant differences in abundances of eight parasite taxa were found across locations sampled in 1996, with most of the differences occurring between fish from Minnesota and Wisconsin waters. Nonparametric discriminant function analyses correctly classified 105 of the 108 fish (97%) from Wisconsin waters in 1994 and 1996 and also correctly classified 9 of the 13 fish (69%) from the one location in Minnesota waters. This indicated that little mixing of lake herring from those regions occurred and that the potential exists to use parasite abundances as a marker of lake herring stock structure. This was the first time that multivariate analysis of parasites have been used in the Great Lakes to assess stock structure of fishes. Because the technique was highly successful at classifying locations of our samples, we recommend that parasite abundances in lake herring from all areas of the lake be analyzed as part of a larger study to determine whether lake herring from populations throughout the lake can be as accurately classified as were fish in our study.

Journal of Great Lakes Research↗
USGS2007

Regional Studies of the Potwar Plateau Area, Northern Pakistan

The papers in this volume are products of a cooperative program between the Geological Survey of Pakistan (GSP) and the U.S. Geological Survey (USGS), sponsored by the Government of Pakistan and the U.S. Agency for International Development. The focus of the program, the Coal Resources Exploration and Assessment Program (COALREAP), was to explore and assess Pakistan?s indigenous coal resources. As part of COALREAP, GSP and USGS geologists conducted regional geologic studies from 1988 to 1991 of the coal-bearing areas in the Potwar region of northern Pakistan. A reference section was selected from which to obtain faunal and floral analyses. The composite sections at Nammal Pass and Nammal Dam served as the basis for this regional reference. Although this Bulletin 2078 is being released in 2007, the writing and technical reviews were completed in 1993, and the chapters reflect the work done until that time. During the long production process for the Bulletin, which ultimately resulted in the oversize plates being digitized, the scientific content of the chapters was not changed, and most reports published since 1993 were not cited. A change in the age of the Patala Formation is discussed below [in the full preface], but the age discussions and illustrations in the chapters were not updated.

Bulletin↗
USGS2008

Concentration and spatial distribution of selected constituents in Detroit River bed sediment adjacent to Grassy Island, Michigan, August 2006

In August 2006, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, collected sediment?core samples from the bed of the Detroit River adjacent to Grassy Island. The goal of the sampling was to assess the distribution and concentration of chemical constituents in sediment adjacent to Grassy Island, which was operated from 1960 to 1982 as a confined disposal facility to hold dredge spoils. On August 31, 2006, seven samples were collected at four locations in the Detroit River on the north, south, east, and west sides of the island. Metals concentrations in the riverbed sediment tended to be higher on the west side of the island, whereas organic?compound concentrations were generally higher on the east side. Comparison of results from this sampling to concentrations reported in previous studies indicates that the concentrations of inorganic constituents, mainly metals, in the riverbed sediment around Grassy Island fell within the range of concentrations found regionally throughout the Detroit River and in most cases have lower mean and median values than found elsewhere regionally in the Detroit River. Comparison of results from the August 31, 2006, sampling to U.S. Environmental Protection Agency risk?based sediment?quality guidelines indicates that 18 organic constituents for which an ecological screening level (ESL), and (or) a threshold effect concentration (TEC), and (or) a probable effect concentration (PEC) has been defined exceeded one or more of these guidelines at least once. Further work would be needed to determine whether constituent concentrations in the river sediment are related to constituent runoff from Grassy Island.

Michigan↗
USGS2019

Assessing water quality from highway runoff at selected sites in North Carolina with the Stochastic Empirical Loading and Dilution Model (SELDM)

In 2015, the U.S. Geological Survey (USGS) entered into a cooperative agreement with the North Carolina Department of Transportation (NCDOT) to develop a North Carolina-enhanced variation of the national Stochastic Empirical Loading and Dilution Model (SELDM) with available North Carolina-specific streamflow and water-quality data and to demonstrate use of the model by documenting selected simulation scenarios. The USGS developed the national SELDM in cooperation with the Federal Highway Administration (FHWA) to provide the tools and techniques necessary for performing stormwater-quality simulations. SELDM uses a stochastic mass-balance approach to estimate combinations of flows, concentrations, and loads of stormwater constituents from the site of interest (often a highway catchment; nonhighway areas, such as a large impervious area at a shopping center complex, also can be used) and the basin upstream from the stormwater outfall to assess the risk for adverse effects of runoff. SELDM also can be used to simulate the effectiveness of volume reduction, hydrograph extension, and water-quality concentration reductions by stormwater best management practices (BMPs), which are designed to help mitigate the effects of runoff on receiving water bodies. Some of the statistical inputs needed for the North Carolina-enhanced SELDM were either calculated or augmented using local or regional data from North Carolina. Streamflow statistics used by SELDM were determined for 266 streamgages across North Carolina on the basis of data available through the 2015 water year. Recession ratio statistics used for triangular hydrographs were also developed for 30 streamgages across the State. The NCDOT identified previous research reports on highway-runoff and BMP studies in North Carolina for review of potential data addition to the national FHWA Highway-Runoff Database (HRDB). Following USGS review of these data, a total of 25,087 event mean concentration values and 1,140 storm events for 39 highway-runoff sites and 195 analytes were uploaded to the national HRDB from six North Carolina highway-runoff research reports and a recent USGS bridge deck runoff study. Using data for 27 streamgages in North Carolina, a total of 57 water-quality transport curves were developed for seven constituents for use in simulating water-quality conditions in the upstream basin. Performance data for three BMPs (bioretention, grass strip or swale, and wetland channel) from NCDOT research data were incorporated into the North Carolina-enhanced SELDM for volume-reduction statistics, including the effectiveness of treating four water-quality constituents (total suspended solids, total nitrogen, total phosphorus, nitrate plus nitrite) and turbidity. Simulations using the North Carolina-enhanced SELDM are presented for two hypothetical upstream basins in the Piedmont ecoregion and one hypothetical highway site to demonstrate how simulations can be used to provide risk-based information about potential effects of stormwater runoff on downstream water quality and the potential for mitigating those risks by using BMPs. The first group of simulations explores the stochastic variability in dilution factors (the ratio of the highway runoff to the total downstream stormflow) for a hypothetical Piedmont rural creek having drainage areas ranging from 1 to 100 square miles. The second group of simulations examines dilution factors based on variations in precipitation, streamflow, and recession ratios for two hypothetical Piedmont upstream basins (rural and urban) where the drainage area was held constant at 25 square miles. These simulations indicate the sensitivity of results to variations in each of the three variables. The third group of simulations examines the effects of varied concentrations in the upstream basin on water-quality conditions downstream from the highway crossing. Variations in upstream water-quality conditions for three constituents (suspended sediment concentration, total nitrogen, and total phosphorus) are based on water-quality transport curves selected from among the 57 curves developed as part of this study to represent low-, medium-, and high-concentration statistics. Simulations completed for this third group also examine the potential effects of grass swale and bioretention BMP treatment on total nitrogen and total phosphorus concentrations in highway runoff. The BMP performance data from the NCDOT research reports were applied in this group of simulations. The stochastic mass-balance approach used in SELDM analyses and simulations provides a strong tool for engineers and water-resource managers to use in exploring a wide range of possible hydrologic and water-quality inputs and their effects on downstream water quality. The results of this study can not only aid engineers and managers in planning for potential adverse effects of runoff at site-specific locations, they can also help the USGS and other Federal and State agencies with oversight responsibilities in stormwater-quality issues to continue gathering data on potential water-quality effects in receiving streams.

North Carolina↗