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At least 289 records · Page 16Linked to original sources

USGS2012

Tagging age-1 Lost River and shortnose suckers with passive integrated transponders, Upper Klamath Lake, Oregon–Summary of 2009–11 effort

A passive integrated transponder (PIT) tagging study was initiated in 2009 for age-1 endangered Lost River and shortnose suckers in Upper Klamath Lake, Oregon, for the purpose of examining causes of mortality, validating estimated age to maturity, and examining movement patterns. This study, which was done opportunistically in 2009 and 2010, received funding in 2011 for a directed tagging effort. Tags were redetected using an existing infrastructure of remote PIT tag readers and tag scanning surveys at American white pelican and double-crested cormorant breeding and loafing areas. Individual fish histories are used to describe the distance, direction, and timing of age-1 sucker movement. Sucker PIT tag detections in the Sprague and Williamson rivers in mid-summer and in autumn indicate age-1 suckers use these tributaries outside of the known spring spawning season. PIT tags detected in bird habitats indicate predation by birds may have been a cause of mortality in 2009. Field conditions prevented scanning bird breeding and loafing areas in Upper Klamath Wildlife National Refuge for tags in 2011, however, limiting our ability to make inferences about bird predation in those years.

Oregon↗

USGS2015

Multi-elemental analysis of aqueous geochemical samples by quadrupole inductively coupled plasma-mass spectrometry (ICP-MS)

Typically, quadrupole inductively coupled plasma-mass spectrometry (ICP-MS) is used to determine as many as 57 major, minor, and trace elements in aqueous geochemical samples, including natural surface water and groundwater, acid mine drainage water, and extracts or leachates from geological samples. The sample solution is aspirated into the inductively coupled plasma (ICP) which is an electrodeless discharge of ionized argon gas at a temperature of approximately 6,000 degrees Celsius. The elements in the sample solution are subsequently volatilized, atomized, and ionized by the ICP. The ions generated are then focused and introduced into a quadrupole mass filter which only allows one mass to reach the detector at a given moment in time. As the settings of the mass analyzer change, subsequent masses are allowed to impact the detector. Although the typical quadrupole ICP-MS system is a sequential scanning instrument (determining each mass separately), the scan speed of modern instruments is on the order of several thousand masses per second. Consequently, typical total sample analysis times of 2–3 minutes are readily achievable for up to 57 elements.

Open-File Report↗

USGS2016

Preliminary geologic mapping of Cretaceous and Tertiary formations in the eastern part of the Little Snake River coal field, Carbon County, Wyoming

In the 1970s and 1980s, C.S. Venable Barclay conducted geologic mapping of areas primarily underlain by Cretaceous coals in the eastern part of the Little Snake River coal field (LSR) in Carbon County, southwest Wyoming. With some exceptions, most of the mapping data were never published. Subsequently, after his retirement from the U.S. Geological Survey (USGS), his field maps and field notebooks were archived in the USGS Field Records. Due to a pending USGS coal assessment of the Little Snake River coal field area and planned geological mapping to be conducted by the Wyoming State Geological Survey, Barclay’s mapping data needed to be published to support these efforts. Subsequently, geologic maps were scanned and georeferenced into a geographic information system, and project and field notes were scanned into Portable Document Format (PDF) files. Data for seventeen 7½-minute quadrangles are presented in this report. This publication is solely intended to compile the mapping data as it was last worked on by Barclay and provides no interpretation or modification of his work.

Wyoming↗

USGS2021

System characterization report on Resourcesat-2 Advanced Wide Field Sensor

Executive Summary This report addresses system characterization of the Indian Space Research Organisation Resourcesat-2 Advanced Wide Field Sensor (AWiFS) and is part of a series of system characterization reports produced and delivered by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence in 2021. These reports present and detail the methodology and procedures for characterization; present technical and operational information about the specific sensing system being evaluated; and provide a summary of test measurements, data retention practices, data analysis results, and conclusions. Resourcesat-2 is a medium-resolution satellite launched in 2011 on the Polar Satellite Launch Vehicle-C16. Resourcesat-2 carries the same sensing elements as Resourcesat-1 (launched in October 2003) and provides continuity for the mission. The objectives of the Resourcesat mission are to provide remote sensing data services to global users, focusing on data for integrated land and water resources management. Resourcesat-2A is identical to Resourcesat-2 and was launched in 2016 on the Polar Satellite Launch Vehicle-C36 launch vehicle for continuity of data and improved temporal resolution. The two satellites operating in tandem improved the revisit capability from 5 days to 2–3 days. The Resourcesat-2 platform is of Indian Remote Sensing Satellites-1C/1D–P3 heritage and was built by the Indian Space Research Organisation. Resourcesat-2 and Resourcesat-2A carry the AWiFS, Linear Imaging Self Scanning-3, and Linear Imaging Self Scanning-4 sensors for medium-resolution imaging. More information on Indian Space Research Organisation satellites and sensors is available in the “2020 Joint Agency Commercial Imagery Evaluation—Remote Sensing Satellite Compendium” and from the manufacturer at https://www.isro.gov.in/ . The Earth Resources Observation and Science Cal/Val Center of Excellence system characterization team completed data analyses to characterize the geometric (interior and exterior), radiometric, and spatial performances. Results of these analyses indicate that AWiFS has an interior geometric performance in the range of −16.080 (−0.268 pixel) to 35.520 meters (m; 0.592 pixel) in easting and −25.680 (−0.428 pixel) to 23.400 m (0.390 pixel) in northing in band-to-band registration, an exterior geometric error of −64.262 (−1.071 pixels) to −19.059 m (−0.318 pixel) in easting and −29.028 (−0.484 pixel) to 41.249 m (0.687 pixel) in northing offset in comparison to the Landsat 8 Operational Land Imager, a radiometric performance in the range of 2.29–2.36 pixels for full width at half maximum, with a modulation transfer function at a Nyquist frequency in the range of 0.030–0.035.

Open-File Report↗

USGS2025

System characterization report on Resourcesat-2A Advanced Wide Field Sensor

Executive Summary This report documents the system characterization of the Indian Space Research Organisation Resourcesat-2A Advanced Wide Field Sensor (AWiFS) and is part of a series of system characterization reports produced by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence. These reports describe the methodology and procedures used for characterization, present technical and operational information about the specific sensing system being evaluated, and provide a summary of test measurements, data retention practices, data analysis results, and conclusions. Resourcesat-2A was launched in 2016 on the Polar Satellite Launch Vehicle-C36; it is identical to Resourcesat-2, and together, they decrease imaging revisit time from 5 days to 2–3 days, providing data continuity and improved temporal resolution. Resourcesat-2 and -2A carry the AWiFS, Linear Imaging Self Scanning-3, and Linear Imaging Self Scanning-4 medium-resolution imaging sensors, continuing the legacy of the Indian Space Research Organisation’s Indian Remote Sensing-1C/1D/P3 satellite programs. More information about Indian Space Research Organisation satellites and sensors is available through the Joint Agency Commercial Imagery Evaluation Earth Observing Satellites Online Compendium and from the Indian Space Research Organisation at https://www.isro.gov.in/ . The Earth Resources Observation and Science Cal/Val Center of Excellence system characterization team assessed the geometric, radiometric, and spatial performance of the Resourcesat-2A AWiFS sensor. Geometric performance is divided into the interior geometric performance of band-to-band registration and the exterior geometric performance of geolocation accuracy. The interior geometric performance had offsets in the range of −1.10 meters (m; −0.020 pixel) to 3.67 m (0.066 pixel) in easting and −5.68 m (−0.101 pixel) to 10.38 m (0.185 pixel) in northing with root mean square error values from 5.60 m (0.100 pixel) to 11.31 m (0.202 pixel) in easting and from 3.00 m (0.054 pixel) to 13.52 m (0.241 pixel) in northing. The exterior geometric performance had mean offsets of −25.29 m in easting and 16.22 m northing with root mean square error values of 26.07 m in easting and 17.60 m in northing compared to the Landsat 8 Operational Land Imager sensor. The radiometric performance had offsets from −0.002 to 0.029 and slopes from 0.733 to 1.012. Spatial performance was in the range of 1.354 to 1.639 pixels for full width at half maximum with a modulation transfer function at a Nyquist frequency in the range of 0.108 to 0.174.

Open-File Report↗

USGS1978

Status of Space Oblique Mercator (SOM) projection (EC 64 Landsat)

The Space Oblique Mercator projection, a concept that was originated by Colvocoresses in 1974, has been mathematically implemented as the first map projection to provide continuous mapping of satellite imagery true to scale along the groundtrack, and within a few millionths of accurate conformal projection. Specifically designed for Landsat (formerly ERTS) imagery, it is also suitable for other satellites with broader scans. Formulas are given for both sphere and ellipsoid. A unique feature is the need for a curved groundtrack and skewed scan lines on the SOM projection, although they would be straight and parallel, respectively, on a normal oblique cylindrical projection.

Open-File Report↗

USGS1979

Mid- and North Atlantic multichannel seismic reflection profiles, 7, 8 A, B, and C, 12 E, F, G, H, I, and J, and 13 A, B, C, D, E, F, G, and H

Available are four multichannel profiles collected by Digicon Geophysical Corporation in 1975 using a 48-channel streamer (3600 m long), and a 27.9 cubic liter airgun array. They were processed in Denver on the Phoenix "I" by William C. Petterson. The processing includes demultiplexing and resampling, geometry and common-depth-point, definition, velocity analysis noise muting, band-pass filtering, time-variant filtering, time-variant deconvolution, and automatic gain control (AGC) sealing, prior to the final profile playout. The release includes pares of or all of four lines off the eastern United States (see map) over the Georges Bank basin and the Long Island platform and upper continental rise. These profiles were collected as a part of a regional arid over the offshore Atlantic sedimentary basins as a part of a continuing program to assess the resource potential using non-proprietary data. Lines 7 and 8 are cross-shelf profiles (280 ken and 400 km long respectively) taken across Georges Basin George Bank, the continental slope and rise east of Massachusetts. A five kilometer gap exists in line 8C near the outer edge of the shelf because the high concentration of lobster pots there prevented a continous traverse through the area. Line 12 (shotpoint 5988 - 14380, parts E, F, G, H, I and J) is along-the-shelf profile, and stretches from the vicinity of Husdon Channel (mid-shelf east of New Jersey) to Browns Bank, 100 km southeast of Nova Scotia, terminating in the vicinity of the Shell Mohawk (B-93) hole. Line 13 (shotpoint 83-11295, 1120 km) traverse the upper Continental rise between Cape Hatteras and Georges Bank. These profiles including velocity scans and shot point maps, may be viewed at U. S. Geological Survey Office, Bldg. B, Quissett Campus, Woods Hole, MA., and U. S. Geological Survey Office, Bldg. 25 at the Denver Federal Center. Copies of maps, scans and profiles can be purchased from the National Geophysical Solar-Terrestrial Data center, Environmental Data Service - NOAA, Code D 621, Boulder, Co. 80303.

Open-File Report↗

USGS1980

High-resolution seismic-reflection profiles collected by the R/V James M. Gilliss, cruise GS 7903-4, in the Baltimore Canyon outer continental shelf area, offshore New Jersey

High-resolution seismic-reflection profiles were collected by the U.S. Geological Survey (USGS) aboard R/V JAMES M. GILLIS (cruise GS 7903-4) from 27 June to 11 July 1979 over the Continental Slope of the Eastern United States between Lindenkohl and Hudson Canyons. These data were acquired as part of a study to determine potential geologic hazards to petroleum development of the Baltimore Canyon trough area. On this cruise, the Continental Slope between Carteret and South Toms Canyons was surveyed along lines spaced one-half nautical mile apart to study the size and distribution of mass-wasting features as a guide to assess the importance of mass-wasting processes on the Continental Slope. The seimsic-reflection profiles were placed to complement other data gathered previously by the USGS and to continue a survey grid begun in 1978 aboard the R/V COLUMBUS !SELIN, cruise CI 7807-1. Track-line distances totaled 1,555 km of 40-in3 air-gun (with wave shaper) profiles, 1, 750 km of 800-J sparker data, and 1,780 km of 3 .5-kHz data. All data are of high quality. A side-scan sonar system was operated briefly along the uppermost Continental Slope to acquire data over 70 km of ship's track. In addition, experimental profiling data were collected from a hydrophone towed at depth over the midslope on the end of the side-scan cable; the surface-towed sparker was used as a sound source. High-resolution profiles were collected by this method over 105 km of track. Navigation was by Loran-C (5-minute fix interval) and satellite. The original data may be inspected at the offices of the U.S. Geological Survey in Woods Hole, Massachusetts 02543. Microfilm copies of the data from this cruise are available for purchase from the National Geophysical and Solar-Terrestrial Data Center (NGSDC), Boulder, Colorado 80303.

Open-File Report↗

USGS1992

The digital geologic map of Colorado in ARC/INFO format: Part A. Documentation

This geologic map was prepared as a part of a study of digital methods and techniques as applied to complex geologic maps. The geologic map was digitized from the original scribe sheets used to prepare the published Geologic Map of Colorado (Tweto 1979). Consequently the digital version is at 1:500,000 scale using the Lambert Conformal Conic map projection parameters of the state base map. Stable base contact prints of the scribe sheets were scanned on a Tektronix 4991 digital scanner. The scanner automatically converts the scanned image to an ASCII vector format. These vectors were transferred to a VAX minicomputer, where they were then loaded into ARC/INFO. Each vector and polygon was given attributes derived from the original 1979 geologic map. This database was developed on a MicroVAX computer system using VAX V 5.4 nd ARC/INFO 5.0 software. UPDATE: April 1995, The update was done solely for the purpose of adding the abilitly to plot to an HP650c plotter. Two new ARC/INFO plot AMLs along with a lineset and shadeset for the HP650C design jet printer have been included. These new files are COLORADO.650, INDEX.650, TWETOLIN.E00 and TWETOSHD.E00. These files were created on a UNIX platform with ARC/INFO 6.1.2. Updated versions of INDEX.E00, CONTACT.E00, LINE.E00, DECO.E00 and BORDER.E00 files that included the newly defined HP650c items are also included. * Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Descriptors: The Digital Geologic Map of Colorado in ARC/INFO Format Open-File Report 92-050

Colorado↗

USGS1992

The digital geologic map of Colorado in ARC/INFO format: Part C. Explanation sheet database

Colorado↗

USGS1992

The digital geologic map of Colorado in ARC/INFO format

Colorado↗

USGS1994

The digital geologic map of Wyoming in ARC/INFO format

This geologic map was prepared as part of a study of digital methods and techniques as applied to complex geologic maps. The geologic map was digitized from the original scribe sheets used to prepare the published Geologic Map of Wyoming (Love and Christiansen, 1985). Consequently, the digital version is at 1:500,000 scale using the Lambert Conformal Conic map projection parameters of the State base map. Stable base contact prints of the scribe sheets were scanned on a Tektronix 4991 digital scanner. The scanner automatically converts the scanned image to an ASCII vector format. These vectors were transferred to a VAX minicomputer, where they were then loaded into ARC/INFO. Each vector and polygon was given attributes derived from the original 1985 geologic map. Descriptors: The Digital Geologic Map of Wyoming in ARC/INFO Format Open-File Report 94-0425

Open-File Report↗

USGS1999

Lithology and aggregate quality attributes for the digital geologic map of Colorado

Colorado↗

USGS2005

Characterization and modes of occurrence of elements in feed coal and coal combustion products from a power plant utilizing low-sulfur coal from the Powder River Basin, Wyoming

The U.S. Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana utility company to determine the physical and chemical properties of feed coal and coal combustion products from a coal-fired power plant. The Indiana power plant utilizes a low-sulfur (0.23 to 0.47 weight percent S) and lowash (4.9 to 6.3 weight percent ash) subbituminous coal from the Wyodak-Anderson coal zone in the Tongue River Member of the Paleocene Fort Union Formation, Powder River Basin, Wyoming. Based on scanning electron microscope and X-ray diffraction analyses of feed coal samples, two mineral suites were identified: (1) a primary or detrital suite consisting of quartz (including beta-form grains), biotite, feldspar, and minor zircon; and (2) a secondary authigenic mineral suite containing alumino-phosphates (crandallite and gorceixite), kaolinite, carbonates (calcite and dolomite), quartz, anatase, barite, and pyrite. The primary mineral suite is interpreted, in part, to be of volcanic origin, whereas the authigenic mineral suite is interpreted, in part, to be the result of the alteration of the volcanic minerals. The mineral suites have contributed to the higher amounts of barium, calcium, magnesium, phosphorus, sodium, strontium, and titanium in the Powder River Basin feed coals in comparison to eastern coals. X-ray diffraction analysis indicates that (1) fly ash is mostly aluminate glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals; and (2) bottom ash is predominantly quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite, and spinel group minerals. Microprobe and scanning electron microscope analyses of fly ash samples revealed quartz, zircon, and monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, wollastonite, and periclase. The abundant calcium and magnesium mineral phases in the fly ash are attributed to the presence of carbonate, clay, and phosphate minerals in the feed coal and their alteration to new phases during combustion. The amorphous diffraction-scattering maxima or glass 'hump' appears to reflect differences in chemical composition of fly ash and bottom ash glasses. In Wyodak-Anderson fly and bottom ashes, the center point of scattering maxima is due to calcium and magnesium content, whereas the glass 'hump' of eastern fly ash reflects variation in aluminum content. The calcium- and magnesium-rich and alumino-phosphate mineral phases in the coal combustion products can be attributed to volcanic minerals deposited in peat-forming mires. Dissolution and alteration of these detrital volcanic minerals occurred either in the peat-forming stage or during coalification and diagenesis, resulting in the authigenic mineral suite. The presence of free lime (CaO) in fly ash produced from Wyodak-Anderson coal acts as a self-contained 'scrubber' for SO3, where CaO + SO3 form anhydrite either during combustion or in the upper parts of the boiler. Considering the high lime content in the fly ash and the resulting hydration reactions after its contact with water, there is little evidence that major amounts of leachable metals are mobilized in the disposal or utilization of this fly ash.

Scientific Investigations Report↗

USGS2007

Benthic habitats and offshore geological resources of Kaloko-Honokohau National Historical Park, Hawai‘i

Kaloko-Honokōhau National Historical Park (KAHO) is one of three National Park lands located along the western coast of the Island of Hawai‘i and the only one to include submerged lands and marine resources within its official boundaries. The park was established in 1978 and is 1,160 acres in size, including 596 acres of marine area. The submerged lands are currently managed by the State of Hawaii, Department of Land and Natural Resources, Division of Aquatic Resources (DLNR-DAR). Marine resources located within KAHO include coral reef and habitat for many marine animals, including the green sea turtle and a variety of fish and invertebrates. In addition, many archeological, cultural, and recreational resources are located within the marine realm of the park. Potential threats and stressors to the modern marine environment include ground-water and surface-water contamination, invasive plants and algae, fishing pressure and use of monofilament gill nets (which can ensnare marine life or become tangled on reefs and be left behind as fishing debris), and visitor use impacts, such as scuba diving and snorkeling. Illegal dumping, oil releases, boat groundings, and other physical damage to reef resources are potential threats from users of the nearby harbor. Special issues of concern for the park include establishing baseline conditions of the offshore resources before the development of adjacent coastal lands. Until this study, only a general knowledge of the distribution of benthic habitats and the characteristics of the offshore region of Kaloko-Honokōhau National Historical Park was available. In 2003, a collaborative project between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program and the National Park Service (NPS) was initiated to develop detailed benthic-habitat classification maps for the marine lands within and adjacent to the park. The intent of this project is to provide baseline maps and a Geographic Information System (GIS) database and description of the biological and geological resources of these marine lands in order to facilitate the management, interpretation, and understanding of park resources. A benthic-habitat classification map was created for the park using existing color aerial photography, Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) bathymetric data, georeferenced underwater video, and still photography. Individual habitat polygons were classified using five basic attributes: (1) major structure or substrate, (2) dominant structure, (3) major biologic cover on the substrate, (4) percentage of major biological cover, and (5) geographic zone. Additional information regarding geology, morphology, and coral species were also noted. Marine resources located within KAHO include coral reef and habitat for many marine animals, including the green sea turtle and a variety of fish and invertebrates. In addition, many archeological, cultural, and recreational resources are located within the marine realm of the park. Potential threats and stressors to the modern marine environment include ground-water and surface-water contamination, invasive plants and algae, fishing pressure and use of monofilament gill nets (which can ensnare marine life or become tangled on reefs and be left behind as fishing debris), and visitor use impacts, such as scuba diving and snorkeling. Illegal dumping, oil releases, boat groundings, and other physical damage to reef resources are potential threats from users of the nearby harbor. Special issues of concern for the park include establishing baseline conditions of the offshore resources before the development of adjacent coastal lands. Until this study, only a general knowledge of the distribution of benthic habitats and the characteristics of the offshore region of Kaloko-Honokōhau National Historical Park was available. In 2003, a collaborative project between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program and the National Park Service (NPS) was initiated to develop detailed benthic-habitat classification maps for the marine lands within and adjacent to the park. The intent of this project is to provide baseline maps and a Geographic Information System (GIS) database and description of the biological and geological resources of these marine lands in order to facilitate the management, interpretation, and understanding of park resources. A benthic-habitat classification map was created for the park using existing color aerial photography, Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) bathymetric data, georeferenced underwater video, and still photography. Individual habitat polygons were classified using five basic attributes: (1) major structure or substrate, (2) dominant structure, (3) major biologic cover on the substrate, (4) percentage of major biological cover, and (5) geographic zone. Additional information regarding geology, morphology, and coral species were also noted.

Hawai'i↗

USGS2011

Analysis of methods to determine storage capacity of, and sedimentation in, Loch Lomond Reservoir, Santa Cruz County, California, 2009

In 2009, the U.S. Geological Survey, in cooperation with the City of Santa Cruz, conducted bathymetric and topographic surveys to determine the water storage capacity of, and the loss of capacity owing to sedimentation in, Loch Lomond Reservoir in Santa Cruz County, California. The topographic survey was done as a supplement to the bathymetric survey to obtain information about temporal changes in the upper reach of the reservoir where the water is shallow or the reservoir may be dry, as well as to obtain information about shoreline changes throughout the reservoir. Results of a combined bathymetric and topographic survey using a new, state-of-the-art method with advanced instrument technology indicate that the maximum storage capacity of the reservoir at the spillway altitude of 577.5 feet (National Geodetic Vertical Datum of 1929) was 8,646 ±85 acre-feet in March 2009, with a confidence level of 99 percent. This new method is a combination of bathymetric scanning using multibeam-sidescan sonar, and topographic surveying using laser scanning (LiDAR), which produced a 1.64-foot-resolution grid with altitudes to 0.3-foot resolution and an estimate of total water storage capacity at a 99-percent confidence level. Because the volume of sedimentation in a reservoir is considered equal to the decrease in water-storage capacity, sedimentation in Loch Lomond Reservoir was determined by estimating the change in storage capacity by comparing the reservoir bed surface defined in the March 2009 survey with a revision of the reservoir bed surface determined in a previous investigation in November 1998. This revised reservoir-bed surface was defined by combining altitude data from the 1998 survey with new data collected during the current (2009) investigation to fill gaps in the 1998 data. Limitations that determine the accuracy of estimates of changes in the volume of sedimentation from that estimated in each of the four previous investigations (1960, 1971, 1982, and 1998) are a result of the limitations of the survey equipment and data-processing methods used. Previously used and new methods were compared to determine the recent (1998-2009) change in storage capacity and the most accurate and cost-effective means to define the reservoir bed surface so that results can be easily replicated in future surveys. Results of this investigation indicate that the advanced method used in the 2009 survey accurately captures the features of the wetted reservoir surface as well as features along the shoreline that affect the storage capacity calculations. Because the bathymetric and topographic data are referenced to a datum, the results can be easily replicated or compared with future results. Comparison of the 2009 reservoir-bed surface with the surface defined in 1998 indicates that sedimentation is occurring throughout the reservoir. About 320 acre-feet of sedimentation has occurred since 1998, as determined by comparing the revised 1998 reservoir-bed surface, with an associated maximum reservoir storage capacity of 8,965 acre-feet, to the 2009 reservoir bed surface, with an associated maximum capacity of 8,646 acre-feet. This sedimentation is more than 3 percent of the total storage capacity that was calculated on the basis of the results of the 1998 bathymetric investigation.

California↗

USGS2004

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of polycyclic aromatic hydrocarbon compounds in sediment by gas chromatography/mass spectrometry

A method for the determination of 28 polycyclic aromatic hydrocarbons (PAHs) and 25 alkylated PAH homolog groups in sediment samples is described. The compounds are extracted from sediment by solvent extraction, followed by partial isolation using high-performance gel permeation chromatography. The compounds are identified and uantitated using capillary-column gas chromatography/mass spectrometry. The report presents performance data for full-scan ion monitoring. Method detection limits in laboratory reagent matrix samples range from 1.3 to 5.1 micrograms per kilogram for the 28 PAHs. The 25 groups of alkylated PAHs are homologs of five groups of isomeric parent PAHs. Because of the lack of authentic standards, these homologs are reported semiquantitatively using a response factor from a parent PAH or a specific alkylated PAH. Precision data for the alkylated PAH homologs are presented using two different standard reference manuals produced by the National Institute of Standards and Technology: SRM 1941b and SRM 1944. The percent relative standard deviations for identified alkylated PAH homolog groups ranged from 1.55 to 6.98 for SRM 1941b and from 6.11 to 12.0 for SRM 1944. Homolog group concentrations reported under this method include the concentrations of individually identified compounds that are members of the group. Organochlorine (OC) pesticides--including toxaphene, polychlorinated biphenyls (PCBs), and organophosphate (OP) pesticides--can be isolated simultaneously using this method. In brief, sediment samples are centrifuged to remove excess water and extracted overnight with dichloromethan (95 percent) and methanol (5 percent). The extract is concentrated and then filtered through a 0.2-micrometer polytetrafluoroethylene syringe filter. The PAH fraction is isolated by quantitatively injecting an aliquot of sample onto two polystyrene-divinylbenzene gel-permeation chromatographic columns connected in series. The compounds are eluted with dichloromethane, a PAH fraction is collected, and a portion of the coextracted interferences, including elemental sulfur, is separated and discarded. The extract is solvent exchanged, the volume is reduced, and internal standard is added. Sample analysis is completed using a gas chromatograph/mass spectrometer and full-scan acquisition.

Water-Resources Investigations Report↗

USGS2022

Absolute accuracy assessment of lidar point cloud using amorphous objects

The accuracy assessment of airborne lidar point cloud typically estimates vertical accuracy by computing RMSEz (root mean square error of the z coordinate) from ground check points (GCPs). Due to the low point density of the airborne lidar point cloud, there is often not enough accurate semantic context to find an accurate conjugate point. To advance the accuracy assessment in full three-dimensional (3D) context, geometric features, such as the three-plane intersection point or two-line intersection point, are often used. Although the point density is still low, geometric features are mathematically modeled from many points. Thus, geometric features provide a robust determination of the intersection point, and the point is considered as a GCP. When no regular built objects are available, we describe the process of utilizing features of irregular shape called amorphous natural objects, such as a tree or a rock. When scanned to a high-density point cloud, an amorphous natural object can be used as ground truth reference data to estimate 3D georeferencing errors of the airborne lidar point cloud. The algorithm to estimate 3D accuracy is the optimization that minimizes the sum of the distance between the airborne lidar points to the ground scanned data. The search volume partitioning was the most important procedure to improve the computational efficiency. We also performed an extensive study to address the external uncertainty associated with the amorphous object method. We describe an accuracy assessment using amorphous objects (108 trees) spread over the project area. The accuracy results for ∆ x , ∆ y , and ∆ z obtained using the amorphous object method were 3.1 cm, 3.6 cm, and 1.7 cm RMSE, along with a mean error of 0.1 cm, 0.1 cm, and 4.5 cm, respectively, satisfying the accuracy requirement of U.S. Geological Survey lidar base specification. This approach shows strong promise as an alternative to geometric feature methods when artificial targets are scarce. The relative convenience and advantages of using amorphous targets, along with its good performance shown here, make this amorphous object method a practical way to perform 3D accuracy assessment.

Remote Sensing↗