SEARCH · USGS Science

Results for “Topographic Map”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79Linked to original sources

USGS2016

LANDFIRE 2010—Updates to the national dataset to support improved fire and natural resource management

The Landscape Fire and Resource Management Planning Tools (LANDFIRE) 2010 data release provides updated and enhanced vegetation, fuel, and fire regime layers consistently across the United States. The data represent landscape conditions from approximately 2010 and are the latest release in a series of planned updates to maintain currency of LANDFIRE data products. Enhancements to the data products included refinement of urban areas by incorporating the National Land Cover Database 2006 land cover product, refinement of agricultural lands by integrating the National Agriculture Statistics Service 2011 cropland data layer, and improved wetlands delineations using the National Land Cover Database 2006 land cover and the U.S. Fish and Wildlife Service National Wetlands Inventory data. Disturbance layers were generated for years 2008 through 2010 using remotely sensed imagery, polygons representing disturbance events submitted by local organizations, and fire mapping program data such as the Monitoring Trends in Burn Severity perimeters produced by the U.S. Geological Survey and the U.S. Forest Service. Existing vegetation data were updated to account for transitions in disturbed areas and to account for vegetation growth and succession in undisturbed areas. Surface and canopy fuel data were computed from the updated vegetation type, cover, and height and occasionally from potential vegetation. Historical fire frequency and succession classes were also updated. Revised topographic layers were created based on updated elevation data from the National Elevation Dataset. The LANDFIRE program also released a new Web site offering updated content, enhanced usability, and more efficient navigation.

Open-File Report↗

USGS2008

Winters-Domengine Total Petroleum System—Northern Nonassociated Gas Assessment Unit of the San Joaquin Basin Province: Chapter 21 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

The Northern Nonassociated Gas Assessment Unit (AU) of the Winters-Domengine Total Petroleum System of the San Joaquin Basin Province consists of all nonassociated gas accumulations in Cretaceous, Eocene, and Miocene sandstones located north of township 15 South in the San Joaquin Valley. The northern San Joaquin Valley forms a northwest-southeast trending asymmetrical trough. It is filled with an alternating sequence of Cretaceous-aged sands and shales deposited on Franciscan Complex, ophiolitic, and Sierran basement. Eocene-aged strata unconformably overlie the thick Cretaceous section, and in turn are overlain unconformably by nonmarine Pliocene-Miocene sediments. Nonassociated gas accumulations have been discovered in the sands of the Panoche, Moreno, Kreyenhagen, andDomengine Formations and in the nonmarine Zilch formation of Loken (1959) (hereafter referred to as Zilch formation). Most hydrocarbon accumulations occur in low-relief, northwest-southeast trending anticlines formed chiefly by differential compaction of sediment and by northeast southwest directed compression during the Paleogene (Bartow, 1991) and in stratigraphic traps formed by pinch out of submarine fan sands against slope shales. To date, 176 billion cubic feet (BCF) of nonassociated recoverable gas has been found in fields within the assessment unit (table 21.1). A small amount of biogenic gas forms near the surface of the AU. Map boundaries of the assessment unit are shown in figures 21.1 and 21.2; in plan view, this assessment unit is identical to the Northern Area Nonassociated Gas play 1007 considered by the U.S. Geological Survey (USGS) in its 1995 National Assessment (Beyer, 1996). The AU is bounded on the east by the mapped limits of Cretaceous sandstone reservoir rocks and on the west by the east flank of the Diablo Range. The southern limit of the AU is the southernmost occurrence of nonassociated thermogenic-gas accumulations. The northern limit of the AU corresponds to the Stanislaus-San Joaquin county line, which also defines the northern boundary of the San Joaquin Basin Province. In the vertical dimension, the AU extends from the uppermost crystalline basement to the topographic surface (fig. 21.3), to allow for the possibility of down-section charge across fault surfaces and up-dip migration. The gas in this AU may be sourced from the Winters- Domengine(?) petroleum system, located in the Sacramento Valley north of the San Joaquin Valley, as defined by Magoon and others (1994a,b) (question mark notation derives from convention of Magoon and Dow, 1994, and indicates speculative genetic relationship between hydrocarbons and source rock). The Winters-Domengine Total Petroleum System defined for this assessment contains about 7.2 trillion cubic feet (TCF) of known, recoverable gas and includes the Rio Vista gas field, which alone accounts for 4 TCF of recoverable gas through 2002 (CDOGGR, 2003). Alternatively, the northern nonassociated gas may be sourced from the Moreno Formation within the San Joaquin Valley itself.

California↗

USGS1985

Geochemical survey of the Devil's Den Roadless Area, Rutland and Windsor counties, Vermont

The Devils Den Roadless Area comprises 8,830 acres of mountainous terrane in the Green Mountain National Forest, Rutland and Windsor Counties, Vt. (Index Map). Ludlow, the nearest large community, is approximately 7 air miles northeast of the study area. The small villages of Weston and East Wallingford are 3 to 5 mi to the south and north, respectively. Total relief is nearly 1,200 ft, ranging from a low elevation of 1,640 ft along the southwestern edge of the area, to a high point of about 2,860 ft in the northwest portion. Principal access is provided by state Route 100 and 155 on the southeast and northeast, and by Forest Service Road 10 along the western boundary. Old logging roads and foot trails allow entry to the interior of the study area. Several swamps and one small pond are located in topographically low areas. Drainage is principally to the south and southeast by tributaries of the south-flowing West River, ultimately discharging into the Connecticut River near Brattleboro. The Devils Den area is named for a large undercut cliff (Dale, 1915, p. 21) developed in Precambrian basement rocks. This undercut cliff forms a broad natural cave immediately west of and below Forest Service Road 10, at the head of Mt. Tabor Brook. Another much smaller cave is present in dolomite of probable Paleozoic (Early Cambrian) age on the east side of the same road. This smaller cave apparently is of artificial origin, having been made during early mining of the dolomite (Dale, 1915, p. 21). This man-made cave is the only evidence of previous mining activity within the study area.

Vermont↗

USGS1951

Geology and ground-water resources of the northern part of the Ranegras Plain area, Yuma County, Arizona

The Ranegras Plain area is part of the Basin and Range province in west-central Arizona. The report discusses rocks of pre-Cambrian, pre-Cambrian (?), Paleozoic (?), Mesozoic (?), Cretaceous (?), Cretaceous and Tertiary, Tertiary (?), Quaternary (?), and Quaternary age. All the Paleozoic (?) and Cretaceous (?) rocks and parts of the Mesozoic (?),Cretaceous and Tertiary, and Tertiary (?) rocks have been mapped as a unit because they are so intensely faulted that detailed mapping was not practical. Rocks older than Quaternary form the mountain ranges bordering the Ranegras Plain. Quaternary alluvium underlies the broad, gently sloping valley floor to depths of generally a few hundred feet, locally more. Well logs indicate that the underlying Tertiary (?) alluvium exceeds 1,100 feet in thickness. The structure of the area is controlled by faulting typical of the Basin and Range province, but the major faults are covered by alluvium and are inferred from topographic features. Ground water occurs in Quaternary and Tertiary (?) alluvium and the best aquifers are in sand and gravel of the Quaternary alluvium. Ground-water movement is, in general, to the northwest. Recharge to the aquifers is predominantly from stream flow resulting from heavy rains. There is also minor or unevaluated recharge from underflow from Butler Valley to the east, andsince 1948seepage from irrigation. Discharge is by pumping and by natural processes of underflow and evapotranspiration. In addition to small domestic and stock wells, only two irrigation wells, in the vicinity of Utting, are in use. No accurate data on pumpage are available. The safe yield from the ground-water reservoir may be less than 5,000 acre-feet and probably does not exceed 10,000 to 15,000 acre-feet per year. The quality of ground water ranges from permissible to unsuitable for irrigation purposes. The fluoride content is generally too high for the water to be considered satisfactory for use by young children.

Open-File Report↗

USGS2005

Comparison of preconstruction and 2003 bathymetric and topographic surveys of Lake McConaughy, Nebraska

The U.S. Geological Survey, in cooperation with The Central Nebraska Public Power and Irrigation District, conducted a study that used bathymetric and topographic surveying in conjunction with Geographical Information Systems techniques to determine the 2003 physical shape, current storage capacity, and the changes in storage capacity of Lake McConaughy that have occurred over the past 62 years. By combining the bathymetric and topographic survey data, the current surface area of Lake McConaughy was determined to be 30,413.0 acres, with a volume of 1,756,300 acre-feet at the lake conservation-pool elevation of 3,266.4 feet above North American Vertical Datum of 1988 (3,265.0 feet above Central datum). To determine the changes in storage of Lake McConaughy, the 2003 survey Digital Elevation Model (DEM) was compared to a preconstruction DEM compiled from historical contour maps. This comparison showed an increase in elevation at the dam site due to the installation of Kingsley Dam. Immediately to the west of the Kingsley Dam is an area of decline where a borrow pit for Kingsley Dam was excavated. The comparison of the preconstruction survey to the 2003 survey also was used to estimate the gross storage capacity reduction that occurred between 1941 and 2002. The results of this comparison indicate a gross storage capacity reduction of approximately 42,372 acre-feet, at the lake conservation-pool elevation of 3,266.4 feet in NAVD 88 (3,265.0 feet in Central datum). By comparing preconstruction and 2003 survey data and subtracting the Kingsley Dam and borrow pit, the total estimated net volume of sediment deposited over the past 62 years is 53,347,124 cubic yards, at an annual average rate of 860,437 cubic yards per year. The approximate decrease in the net storage capacity occurring over the past 62 years is 33,066 acre-feet, at an annual average decrease of approximately 533 acre-feet per year, which has resulted in a 1.8 percent decrease in storage capacity of Lake McConaughy. The lake has accumulated most of the sediment in the original river channel and in the west end of the delta area on the upstream end of the lake.

Nebraska↗

USGS2011

Hydrologic assessment of three drainage basins in the Pinelands of southern New Jersey, 2004-06

The New Jersey Pinelands is an ecologically diverse area in the southern New Jersey Coastal Plain, most of which overlies the Kirkwood-Cohansey aquifer system. The demand for groundwater from this aquifer system is increasing as local development increases. Because any increase in groundwater withdrawals has the potential to affect streamflows and wetland water levels, and ultimately threaten the ecological health and diversity of the Pinelands ecosystem, the U.S. Geological Survey, in cooperation with the New Jersey Pinelands Commission, began a multi-phase hydrologic investigation in 2004 to characterize the hydrologic system supporting the aquatic and wetland communities of the New Jersey Pinelands area (Pinelands). The current investigation of the hydrology of three representative drainage basins in the Pinelands (Albertson Brook, McDonalds Branch, and Morses Mill Stream basins) included a compilation of existing data; collection of water-level and streamflow data; mapping of the water-table altitude and depth to the water table; and analyses of water-level and streamflow variability, subsurface gradients and flow patterns, and water budgets. During 2004-06, a hydrologic database of existing and new data from wells and stream sites was compiled. Methods of data collection and analysis were defined, and data networks consisting of 471 wells and 106 surface-water sites were established. Hydrographs from 26 water-level-monitoring wells and four streamflow-gaging stations were analyzed to show the response of water levels and streamflow to precipitation and recharge with respect to the locations of these wells and streams within each basin. Water-level hydrographs show varying hydraulic gradients and flow potentials, and indicate that responses to recharge events vary with well depth and proximity to recharge and discharge areas. Results of the investigation provide a detailed characterization of hydrologic conditions, processes, and relations among the components of the hydrologic cycle in the Pinelands. In the Pinelands, recharge replenishes the aquifer system and contributes to groundwater flow, most of which moves to wetlands and surface water where natural discharge occurs. Some groundwater flow is intercepted by supply wells. Recharge rates generally are highest during the non-growing season and are inversely related to evapotranspiration. Analysis of subsurface hydraulic gradients, water-table fluctuations, and streamflow variability indicates a strong linkage between groundwater and wetlands, lakes and streams. Gradient analysis indicates that most wetlands are in groundwater discharge areas, but some wetlands are in groundwater recharge areas. The depth to the water table ranges from zero at surface-water features up to about 10 meters in topographically high areas. Depth to water fluctuates seasonally, and the magnitude of these fluctuations generally increases with distance from surface water. Variations in the permeability of the soils and sediments of the aquifer system strongly affect patterns of water movement through the subsurface and the interaction of groundwater with wetlands, lakes and streams. Mean annual streamflow during 2004-06 ranged from 83 to 106 percent of the long-term mean annual discharge, indicating that the data-collection period can be considered representative of average conditions. Measurements of groundwater levels, stream stage, and stream discharge and locations of start-of-flow are illustrated in basin-wide maps of water-table altitude, depth to the water table, and stream base flow during the period. Water-level data collected along 15 hydrologic transects that span the range of environments from uplands through wetlands to surface water were used to determine hydraulic gradients, potential flow directions, and areas of recharge and discharge. These data provide information about the localized interactions of groundwater with wetlands and surface water. Wetlands were categorized with r

New Jersey↗

USGS1979

Evaluation of Landsat multispectral scanner images for mapping altered rocks in the East Tintic Mountains, Utah

The East Tintic Mountains, Utah consist of folded and faulted Paleozoic sedimentary rocks, which are partly covered by Tertiary volcanic rocks. Clastic rocks dominate the lower one-third of the Paleozoic section, whereas carbonate rocks with subordinate amounts of shale and elastic rocks predominate in the remainder. Some of the rocks, especially the Tintic Quartzite and some shales, are commonly limonitic, an important factor in analysis of Landsat MSS images. The volcanic rocks, mainly tuffs, flows, and agglomerates of quartz latitic and latitic composition, are limonitic in a few places where hematite is present in the groundmass. Emplacement of monzonite and biotite monzonite porphyry bodies resulted in several types of altered rocks. Most widespread are argillized and silicified rocks, which are commonly bleached and limonitic. Locally, the intrusive rocks arc also altered. Hydrothermal dolomite is common in the northern part of the area, and in the East Tintic mining district, calcitic, chloritic, and weakly argillized volcanic rocks and pebble dikes are widespread. Volcanic rocks subjected to an early phase of "intravolcanic weathering" in this district are weakly altered but commonly limonitic. Barren as well as mineralized veins are present throughout the study area. In situ spectral reflectance curves representing the most abundant altered and unaltered rocks show that the argillized and silicified rocks generally have intense ferric-iron and hydroxyl absorption bands owing to the presence of iron-oxide and hydroxyl-bearing phases, respectively. These features are generally absent in the unaltered rocks, except the limonitic rocks, which have prominent iron absorption hands. Both spectral features are weakly expressed in the volcanic rocks subjected to accelerated weathering, On the other hand, hydrothermal dolomite and calcitic volcanic rocks generally lack both features, and thus are spectrally similar to the unaltered rocks. Chloritic rocks are of limited distribution and have not been measured spectrally. Most of the silicified and argillized areas are apparent in Skylab S190B, high altitude-, and low altitude color aerial photographs because of the high albedo of these rocks. However, many unaltered rocks have similar albedos and therefore are not distinguishable from the altered rocks. Moreover, very little color information is available in these photographs. These problems are further complicated by brightness variations related to topographic slope. MSS ratio images were generated to subdue the effects of topographic slope and albedo, and combined into several color composite images for displaying the spectral reflectance differences between the most widespread altered and unaltered rocks. The most effective combination proved to be MSS 4/5, MSS 4/6, and MSS 6/7 using blue, yellow and magenta diazo films, respectively, rather than the MSS 4/5, MSS 5/6, and MSS 6/7 combination used so successfully in south-central Nevada. Consideration of schematic frequency distributions of ratio values for these two areas suggests that the lack of enhancement of limonitic rocks in MSS 5/6 images of the present study area is due to the higher frequency of low ratios representing vegetation. Comparison of a limonitic bedrock map produced by scanning the optimum color-ratio composite image with a map of the silicified rocks shows good agreement, except where they are obscured by vegetation. Measurements of vegetation density indicate that shrub cover and. juniper, pinyon, and sage cover greater than 40-50 and 33-43 percent, respectively, obscure limonitic rocks in these images. Argillized rocks, the most widely distributed altered rock type, were consistently detected in exposed areas. On the other hand, hydrothermal dolomite and calcitic and chloritic volcanic rocks are not portrayed in the limonitic bedrock map because of their general lack of limonite. Some altered rocks, especially veins and pebble dikes, are too small to be detected by the MSS except where they are closely spaced and well exposed. Another important limitation is that exposures of unaltered limonitic sedimentary and volcanic rocks are included in the limonitic bedrock map. Analysis of in situ spectral reflectance measurements indicates that this limitation can be largely overcome by obtaining radiance information in the 2.2 and 1.6 μ m regions.

Utah↗

USGS1996

Analysis of fractures intersecting Kahi Puka Well 1 and its relation to the growth of the island of Hawaii

As part of the Hawaii Scientific Drilling Project, Kahi Puka Well 1 penetrated about 275 m of Mauna Loa basalts overlying a sequence of Mauna Kea flow units as it was drilled and cored to a total depth of 1053 m below land surface. A borehole televiewer (BHTV) was run in most of the well in successive stages prior to casing in order to obtain magnetically oriented acoustic images of the borehole wall. A total of 283 individual fractures were identified from this log and characterized in terms of strike and dip. These data are divided into three vertical sections based upon age and volcanic source, and lower hemisphere stereographic plots identify two predominant, subparallel fracture subsets common to each section. Assuming that most of the steeply dipping fractures observed in the BHTV log are tensile features generated within basalt flows during deposition and cooling, this fracture information can be combined with models of the evolution of the island of Hawaii to investigate the depositional history of these Mauna Loa and Mauna Kea basalts over the past 400 kyr. The directions of high-angle fractures appear to be generally parallel to topography or to the coastline at the time of deposition, as is supported by surface mapping of modern flows. Consequently, an overall counterclockwise rotation of about 75?? in the strike of these fractures from the bottom to the top of the well represents a systematic change in depositional slope direction over time. We attribute the observed rotation in the orientations of the two predominant fracture subsets over the past 400 kyr to changes in the configurations of volcanic sources during shield building and to the structural interference of adjacent volcanoes that produces shifts in topographic patterns.

Journal of Geophysical Research B: Solid Earth↗

USGS1995

Geologic map and structure sections of the Clear Lake Volcanics, Northern California

The Clear Lake Volcanics are located in the California Coast Ranges about 150 km north of San Francisco. This Quaternary volcanic field has erupted intermittently since 2.1 million years ago. This volcanic field is considered a high-threat volcanic system (Ewert and others, 2005) The adjacent Geysers geothermal field, largest power-producing geothermal field in the world, is powered by the magmatic heat source for the volcanic field. This report consists of three sheets that include the geologic map, one table, two figures, three cross sections, description of map units, charts of standard and diagrammatic correlation of map units, and references. This map supersedes U.S. Geological Survey Open-File Report 76-751. Descriptions of map units are grouped by geographic area. Summaries of the evolution, chemistry, structure, and tectonic setting of the Clear Lake Volcanics are given in Hearn and others (1981) and Donnelly-Nolan and others (1981). The geology of parts of the area underlain by the Cache Formation is based on mapping by Rymer (1981); the geology of parts of the areas underlain by the Sonoma Volcanics, Franciscan assemblage, and Great Valley sequence is based on mapping by McLaughlin (1978). Volcanic compositional map units are basalt, basaltic andesite, andesite, dacite, rhyodacite, and rhyolite, based on SiO2 content. Included in this report are maps showing the distribution of volcanic rocks through time and a chart showing erupted volumes of different lava types through time. A table gives petrographic data for each map unit by mineral type, abundance, and size. Most ages are potassium-argon (K/Ar) ages determined for whole-rock samples and mineral separates by Donnelly-Nolan and others (1981), unless otherwise noted. A few ages are carbon-14 ages or were estimated from geologic relationships. Magnetic polarities are from Mankinen and others (1978; 1981) or were determined in the field by B.C. Hearn, Jr., using a portable fluxgate magnetometer. Thickness for most units is estimated from topographic relief except where drill-hole data were available.

California↗

USGS2009

Reservoir uncertainty, Precambrian topography, and carbon sequestration in the Mt. Simon Sandstone, Illinois Basin

Sequestration sites are evaluated by studying the local geological structure and confirming the presence of both a reservoir facies and an impermeable seal not breached by significant faulting. The Cambrian Mt. Simon Sandstone is a blanket sandstone that underlies large parts of Midwest United States and is this region's most significant carbon sequestration reservoir. An assessment of the geological structure of any Mt. Simon sequestration site must also include knowledge of the paleotopography prior to deposition. Understanding Precambrian paleotopography is critical in estimating reservoir thickness and quality. Regional outcrop and borehole mapping of the Mt. Simon in conjunction with mapping seismic reflection data can facilitate the prediction of basement highs. Any potential site must, at the minimum, have seismic reflection data, calibrated with drill-hole information, to evaluate the presence of Precambrian topography and alleviate some of the uncertainty surrounding the thickness or possible absence of the Mt. Simon at a particular sequestration site. The Mt. Simon is thought to commonly overlie Precambrian basement granitic or rhyolitic rocks. In places, at least about 549 m (1800 ft) of topographic relief on the top of the basement surface prior to Mt. Simon deposition was observed. The Mt. Simon reservoir sandstone is thin or not present where basement is topographically high, whereas the low areas can have thick Mt. Simon. The paleotopography on the basement and its correlation to Mt. Simon thickness have been observed at both outcrops and in the subsurface from the states of Illinois, Ohio, Wisconsin, and Missouri. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗

USGS1986

Aeromagnetic map of the Wet Beaver Roadless Area, Yavapai and Coconino counties, Arizona

The Wet Beaver Roadless Area includes 9,890 acres (15.4 mi2) of the Coconino National Forest and is in T. 15 N., Rs. 6, 7, and 8 E., Yavapai and Coconino Counties, central Arizona. Camp Verde, the nearest major population center, is about 13 mi southwest of the road less area. The area boundary closely follows the rim of the steep-walled canyon cut by Wet Beaver Creek into the gently westward sloping surface of the Colorado Plateau. The mouth of the canyon and the western boundary of the roadless area are near the Mogollon Rim, an escarpment that marks the southwestern margin of the Colorado Plateau. Here, the plateau surface falls off sharply in the Verde Valley, and Wet Beaver Creek flows 12 mi farther west where it joins the Verde River, the master stream of the region. The maximum elevation within the area, just east of Hog Hill, is 6,470 ft. The lowest point, at 4,000 ft, is the stream bed of Wet Beaver Creek near the western area boundary. Topographic relief within the area ranges from 1,200 ft near the mouth of the canyon at Casner Butte to about 150 ft at the eastern boundary. Perennial springs, located south of Hog Hill, discharge about 1,200-1,500 gallons of water per minute into Wet Beaver Creek (Twenter and Metzger, 1963, p. 94). The western boundary of the roadless area and the mouth of Wet Beaver Creek canyon are accessible by Forest Service roads from either Camp Verde or the Sedona interchange on Interstate Highway 17. Various points along the canyon rim and the area boundary can be reached by unimproved roads, jeep trails, and pack trails. The canyon floor is accessible only on foot; in several places, deep pools require a swim or steep climb and descent for traverse of the canyon.

Arizona↗

USGS2022

Regional-scale mapping of landscape response to extreme precipitation using repeat lidar and object-based image analysis

Extreme precipitation events may cause flooding, slope failure, erosion, deposition, and damage to infrastructure over a regional scale, but the impacts of these events are often difficult to fully characterize. Regional-scale landscape change occurred during an extreme rain event in June 2012 in northeastern Minnesota. Landscape change was documented by 8,000 km 2 of airborne lidar data collected before and after the event. Following improved alignment of the lidar point data and reducing error using insight from analysis of extensive stable areas, elevation differences were classified into map objects representing geomorphic change in relation to process and landscape position using object-based image analysis. This remote mapping compares favorably to field and imagery-based mapping and provides the basis for volumetric sediment budgeting. Elevation differences in these objects indicate that 4.5 × 10 6 ± 1.0 × 10 6 m 3 of sediment was eroded in the study area. Of this, 2.5 × 10 6 ± 3.3 × 10 5 m 3 was deposited in deposits on hillslopes and valley floors, and 2.0 × 10 6 ± 4.6 × 10 5 m 3 were removed from watersheds and exported to the Saint Louis River Estuary and Lake Superior. Multivariate logistic regression analysis emphasized that topographic slope and presence of glaciolacustrine clay lithology are the primary control on landslide occurrence, and landslides occur most frequently on slopes within tens of meters of stream channels. These results provide the basis to anticipate the impacts of similar future storm events. Because precipitation events are forecast to continue to increase in frequency and intensity owing to climate change, characterizing and anticipating their effects may support hazard planning.

Minnesota↗

USGS2023

National map of focus areas for potential critical mineral resources in the United States

Introduction The U.S. Geological Survey (USGS) launched the Earth Mapping Resources Initiative (Earth MRI) to modernize the surface and subsurface geologic mapping of the United States, with a focus on identifying areas that may have the potential to contain critical mineral resources. EarthMRI can inform strategies to ensure secure and reliable domestic critical mineral supplies for the United States as mandated by Executive Order 13817 and the Infrastructure and Jobs Act of 2021 (Public Law 117–58, 135 Stat. 529). Earth MRI is a collaborative effort between the USGS and the State geological surveys as represented by the Association of American State Geologists to identify, prioritize, and acquire new geoscience data for geographic areas, or focus areas, across the Nation that have potential to host critical mineral resources. Mapping of focus areas was based on a framework of mineral systems and their associated mineral deposit types that could possibly host critical minerals. Using readily available geologic, geophysical, geochemical, and mineral deposit data, teams of USGS scientists worked with representatives of State geological surveys in a series of workshops to outline focus areas that contain evidence of key features for one or more mineral systems. These areas can be used to guide future efforts to collect new geologic, geophysical, geochemical, and topographic data that focus on critical minerals through Earth MRI.

Fact Sheet↗

USGS2004

The nucleus of Comet Borrelly: A study of morphology and surface brightness

Stereo images obtained during the DS1 flyby were analyzed to derive a topographic model for the nucleus of Comet 19P/Borrelly for morphologic and photometric studies. The elongated nucleus has an overall concave shape, resembling a peanut, with the lower end tilted towards the camera. The bimodal character of surface-slopes and curvatures support the idea that the nucleus is a gravitational aggregate, consisting of two fragments in contact. Our photometric modeling suggests that topographic shading effects on Borrelly's surface are very minor (<10%) at the given resolution of the terrain model. Instead, albedo effects are thought to dominate Borrelly's large variations in surface brightness. With 90% of the visible surface having single scattering albedos between 0.008 and 0.024, Borrelly is confirmed to be among the darkest of the known Solar System objects. Photometrically corrected images emphasize that the nucleus has distinct, contiguous terrains covered with either bright or dark, smooth or mottled materials. Also, mapping of the changes in surface brightness with phase angle suggests that terrain roughness at subpixel scale is not uniform over the nucleus. High surface roughness is noted in particular near the transition between the upper and lower end of the nucleus, as well as near the presumed source region of Borrelly's main jets. Borrelly's surface is complex and characterized by distinct types of materials that have different compositional and/or physical properties.

Icarus↗

USGS2008

Sediment deposition, erosion, and bathymetric change in central San Francisco Bay: 1855-1979

Central San Francisco Bay is the hub of a dynamic estuarine system connecting the San Joaquin and Sacramento River Deltas, Suisun Bay, and San Pablo Bay to the Pacific Ocean and South San Francisco Bay. To understand the role that Central San Francisco Bay plays in sediment transport throughout the system, it is necessary to first determine historical changes in patterns of sediment deposition and erosion from both natural and anthropogenic forces. The first extensive hydrographic survey of Central San Francisco Bay was conducted in 1853 by the National Ocean Service (NOS) (formerly the United States Coast and Geodetic Survey (USCGS)). From 1894 to 1979, four additional surveys, composed of a total of approximately 700,000 bathymetric soundings, were collected within Central San Francisco Bay. Converting these soundings into accurate bathymetric models involved many steps. The soundings were either hand digitized directly from the original USCGS and NOS hydrographic sheets (H-sheets) or obtained digitally from the National Geophysical Data Center's (NGDC) Geophysical Data System (GEODAS) (National Geophysical Data Center, 1996). Soundings were supplemented with contours that were either taken directly from the H-sheets or added in by hand. Shorelines and marsh areas were obtained from topographic sheets. The digitized soundings, depth contours, shorelines, and marsh areas were entered into a geographic information system (GIS) and georeferenced to a common horizontal datum. Using surface modeling software, bathymetric grids with a horizontal resolution of 25 m were developed for each of the five hydrographic surveys. Before analyses of sediment deposition and erosion were conducted, interpolation bias was removed and all of the grids were converted to a common vertical datum. These bathymetric grids were then used to develop bathymetric change maps for subsequent survey periods and to determine long-term changes in deposition and erosion by calculating volumes and rates of net sediment change. Central San Francisco Bay experienced periods of both deposition and erosion, but overall experienced a net gain in sediment from 1855 to 1979 of approximately 42x10 6 m 3 (0.33x10 6 m 3 / yr). Over this same time period, 92 percent of the tidal marsh and 69 percent of the intertidal mudflats were lost as human activity increased and the shorefront was developed. During the first time period, from 1855 to 1895, Central San Francisco Bay was erosional, losing roughly 2x10 6 m 3 / yr of sediment. The next time period was depositional, with a net gain of approximately 3x10 6 m 3 / yr of sediment from 1895 to 1947. The last time period, from 1947 to 1979, was erosional again, losing roughly 2x10 6 m 3 / yr of sediment. Sedimentation patterns also varied spatially. The northern part of Central San Francisco Bay was depositional during all change periods while the eastern region alternated between erosional and depositional. Central San Francisco Bay sedimentation patterns have also been strongly impacted by anthropogenic activities, such as dredging and dredge disposal, borrow pits, and sand mining. For example, bathymetric change at a borrow pit created near Bay Farm Island sometime between the 1947 and 1979 surveys indicates roughly 25x10 6 m 3 of sediment was removed from the system

California↗

USGS2014

Monitoring fine-sediment volume in the Colorado River ecosystem, Arizona: construction and analysis of digital elevation models

Digital elevation models (DEMs) of eleven 2–5 kilometer reaches of the Colorado River ecosystem (CRE) in Grand Canyon were constructed from repeat bathymetric and topographic surveys collected between August 2000 and December 2004. The DEMs will be used by researchers to study the effects of Glen Canyon Dam (GCD) operations on the sediment resources of the CRE in Grand Canyon by quantifying morphological changes and sediment transfer within and among the study reaches. Airborne surveys collected light detection and ranging (lidar) and photogrammetric data, whereas ground topographic and bathymetric data were collected simultaneously on river trips. Surveys were conducted in August 2000, September 2000, May 2002, May 2004, November 2004, and December 2004. The aerial lidar and photogrammetric data were merged with the ground topographic and bathymetric data to create DEMs of the study areas with a grid resolution of 1 meter. For each survey period, the vertical component of uncertainty (specifically, reproducibility or precision) was estimated for each data type (lidar/photogrammetry, ground surveys, bathymetry) and for two different types of bed-surface texture (smooth and rough). The resulting DEMs from this study are a valuable contribution to ongoing efforts in assessing the effects of GCD operations on the CRE. The DEMs can be used to map the spatial characteristics of geomorphic change within the study reaches and to estimate sediment budgets for different time periods by calculating the difference in sediment volume between surveys. In addition, the DEMs provide essential boundary conditions for numerical models of sediment transport and deposition, as well as help define the spatial distribution of habitat for fisheries investigations.

Arizona↗

USGS2013

An evaluation of automated GIS tools for delineating karst sinkholes and closed depressions from 1-meter LIDAR-derived digital elevation data

LiDAR (Light Detection and Ranging) surveys of karst terrains provide high-resolution digital elevation models (DEMs) that are particularly useful for mapping sinkholes. In this study, we used automated processing tools within ArcGIS (v. 10.0) operating on a 1.0 m resolution LiDAR DEM in order to delineate sinkholes and closed depressions in the Boyce 7.5 minute quadrangle located in the northern Shenandoah Valley of Virginia. The results derived from the use of the automated tools were then compared with depressions manually delineated by a geologist. Manual delineation of closed depressions was conducted using a combination of 1.0 m DEM hillshade, slopeshade, aerial imagery, and Topographic Position Index (TPI) rasters. The most effective means of visualizing depressions in the GIS was using an overlay of the partially transparent TPI raster atop the slopeshade raster at 1.0 m resolution. Manually identified depressions were subsequently checked using aerial imagery to screen for false positives, and targeted ground-truthing was undertaken in the field. The automated tools that were utilized include the routines in ArcHydro Tools (v. 2.0) for prescreening, evaluating, and selecting sinks and depressions as well as thresholding, grouping, and assessing depressions from the TPI raster. Results showed that the automated delineation of sinks and depressions within the ArcHydro tools was highly dependent upon pre-conditioning of the DEM to produce "hydrologically correct" surface flow routes. Using stream vectors obtained from the National Hydrologic Dataset alone to condition the flow routing was not sufficient to produce a suitable drainage network, and numerous artificial depressions were generated where roads, railways, or other manmade structures acted as flow barriers in the elevation model. Additional conditioning of the DEM with drainage paths across these barriers was required prior to automated 2delineation of sinks and depressions. In regions where the DEM had been properly conditioned, the tools for automated delineation performed reasonably well as compared to the manually delineated depressions, but generally overestimated the number of depressions thus necessitating manual filtering of the final results. Results from the TPI thresholding analysis were not dependent on DEM pre-conditioning, but the ability to extract meaningful depressions depended on careful assessment of analysis scale and TPI thresholding.

Conference Paper↗

USGS2013

Massachusetts Shoreline Change Mapping and Analysis Project, 2013 Update

Information on rates and trends of shoreline change can be used to improve the understanding of the underlying causes and potential effects of coastal erosion on coastal populations and infrastructure and can support informed coastal management decisions. In this report, we summarize the changes in the historical positions of the shoreline of the Massachusetts coast for the 165 years from 1844 through 2009. The study area includes the Massachusetts coastal region from Salisbury to Westport, including Cape Cod, as well as Martha’s Vineyard, Nantucket, and the Elizabeth Islands. New statewide shoreline data were developed for approximately 1,804 kilometers (1,121 miles) of shoreline using color aerial orthoimagery from 2008 and 2009 and topographic lidar from 2007. The shoreline data were integrated with existing historical shoreline data from the U.S. Geological Survey (USGS) and Massachusetts Office of Coastal Zone Management (CZM) to compute long- (about 150 years) and short-term (about 30 years) rates of shoreline change. A linear regression method was used to calculate long- and short-term rates of shoreline change at 26,510 transects along the Massachusetts coast. In locations where shoreline data were insufficient to use the linear regression method, short-term rates were calculated using an end-point method. Long-term rates of shoreline change are calculated with (LTw) and without (LTwo) shorelines from the 1970s and 1994 to examine the effect of removing these data on measured rates of change. Regionally averaged rates are used to assess the general characteristics of the two-rate computations, and we find that (1) the rates of change for both LTw and LTwo are essentially the same; (2) including more data slightly reduces the uncertainty of the rate, which is expected as the number of shorelines increases; and (3) the data for the shorelines from the 1970s and 1994 are not outliers with respect to the long-term trend. These findings are true for regional averages, but may not hold at specific transects.

Massachusetts↗