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At least 1,135 records · Page 63Linked to original sources

Quaternary geomorphology and modern coastal development in response to an inherent geologic framework: An example from Charleston, South Carolina

Coastal landscapes evolve over wide-ranging spatial and temporal scales in response to physical and biological processes that interact with a wide range of variables. To develop better predictive models for these dynamic areas, we must understand the influence of these variables on coastal morphologies and ultimately how they influence coastal processes. This study defines the influence of geologic framework variability on a classic mixed-energy coastline, and establishes four categorical scales of spatial and temporal influence on the coastal system. The near-surface, geologic framework was delineated using high-resolution seismic profiles, shallow vibracores, detailed geomorphic maps, historical shorelines, aerial photographs, and existing studies, and compared to the long- and short-term development of two coastal compartments near Charleston, South Carolina. Although it is clear that the imprint of a mixed-energy tidal and wave signal (basin-scale) dictates formation of drumstick barriers and that immediate responses to wave climate are dramatic, island size, position, and longer-term dynamics are influenced by a series of inherent, complex near-surface stratigraphic geometries. Major near-surface Tertiary geometries influence inlet placement and drainage development (island-scale) through multiple interglacial cycles and overall channel morphology (local-scale). During the modern marine transgression, the halo of ebb-tidal deltas greatly influence inlet region dynamics, while truncated beach ridges and exposed, differentially erodable Cenozoic deposits in the active system influence historical shoreline dynamics and active shoreface morphologies (block-scale). This study concludes that the mixed-energy imprint of wave and tide theories dominates general coastal morphology, but that underlying stratigraphic influences on the coast provide site-specific, long-standing imprints on coastal evolution.

Journal of Coastal Research↗

Predictions of turbidity due to enhanced sediment resuspension resulting from sea-level rise on a fringing Coral Reef: Evidence from Molokai, Hawaii

Accelerating sea-level rise associated with global climate change will affect sedimentary processes on coral reefs and other shoreline environments by increasing energy and sediment resuspension. On reefs, sedimentation is known to increase coral stress and bleaching as particles that settle on coral surfaces interfere with photosynthesis and feeding, and turbidity induced by suspended sediment reduces incident light levels. Using relationships developed from observations of wave orbital velocity, water-surface elevation, and suspended-sediment concentration on a fringing reef flat of Molokai, Hawaii, predictions of the average daily maximum in suspended-sediment concentration increase from ~11 mg/l to ~20 mg/l with 20 cm sea-level rise. The duration of time concentrations exceeds 10 mg/l increases from 9 to 37. An evaluation of the reduction of wave energy flux through breaking and frictional dissipation across the reef flat shows an increase of ~80 relative to the present will potentially reach the shoreline as sea level increases by 20 cm. Where the shoreline exists on low, flat terrain, the increased energy could cause significant erosion of the shoreline. Considering the sediment budget, the sediment flux is predicted to increase and removal of fine-grained sediment may be expedited on some fringing reefs, and sediment in storage on the inner reef could ultimately be reduced. However, increased shoreline erosion may add sediment and offset removal from the reef flat. The shifts in sediment availability and transport that will occur as result of a modest increase in sea level have wide application to fringing coral reefs elsewhere, as well as other shoreline environments. ?? 2010 the Coastal Education & Research Foundation (CERF).

Journal of Coastal Research↗

Liquefaction evidence for at least two strong Holocene paleo-earthquakes in central and southwestern Illinois, USA

Two strong mid-Holocene earthquakes in Illinois have been documented by paleoliquefaction features such as clastic dikes, sills, and detachments of fine-grained sediment that sunk into liquefied sand. At least one paleo-earthquake occurred in central Illinois about 35 km NE of Springfield, probably sometime between 5,900 and 7,400 yr BP. Dike widths are as much as 0.4 m near the energy center of the earthquake. Outward from this center, dike widths attenuate and ultimately disappear at about 35 km. More than one paleo-earthquake is probably represented by liquefaction features near Springfield. Another paleo-earthquake that appears to have been centered about 65 km ESE of St. Louis, Missouri, occurred near 5,700 yr BP. The energy center is inferred as being in Illinois, and most likely near lowermost Shoal Creek where the meizoseismal region is defined by dikes as wide as 0.5 m and by a regional abundance of dikes. Dikes from this earthquake probably extend at least as far as 35 km from its inferred energy center. The earthquake near Shoal Creek and one earthquake near Springfield almost certainly exceeded M 6. The paleomagnitudes can be more closely bracketed by geotechnical testing and analysis, when used in conjunction with existing data.

Illinois↗

Assessing global geologic carbon dioxide storage resources

The U.S. Geological Survey (USGS), in conjunction with the U.S. Department of Energy (U.S. DOE) Office of Fossil Energy and Carbon Management (FECM), the IEA Greenhouse Gas R&D Programme (IEAGHG), and the Clean Energy Ministerial Carbon Capture, Utilization and Storage Initiative (CEM-CCUS Initiative), plans to work with partner nations to assess geologic carbon dioxide (CO2) storage resources globally. The goal of this work is to help countries, particularly those with emerging economies, understand the mass of CO2 they could potentially store in geologic units within their borders. Knowledge of the CO2 storage resources in their geologic units can provide countries pathways for reducing emissions to meet their future climate mitigation goals.

Conference Paper↗

Sage-grouse habitat selection during winter in Alberta

Greater sage-grouse (Centrocercus urophasianus) are dependent on sagebrush (Artemisia spp.) for food and shelter during winter, yet few studies have assessed winter habitat selection, particularly at scales applicable to conservation planning. Small changes to availability of winter habitats have caused drastic reductions in some sage-grouse populations. We modeled winter habitat selection by sage-grouse in Alberta, Canada, by using a resource selection function. Our purpose was to 1) generate a robust winter habitat-selection model for Alberta sage-grouse; 2) spatially depict habitat suitability in a Geographic Information System to identify areas with a high probability of selection and thus, conservation importance; and 3) assess the relative influence of human development, including oil and gas wells, in landscape models of winter habitat selection. Terrain and vegetation characteristics, sagebrush cover, anthropogenic landscape features, and energy development were important in top Akaike's Information Criterionselected models. During winter, sage-grouse selected dense sagebrush cover and homogenous less rugged areas, and avoided energy development and 2-track truck trails. Sage-grouse avoidance of energy development highlights the need for comprehensive management strategies that maintain suitable habitats across all seasons. ?? 2010 The Wildlife Society.

Journal of Wildlife Management↗

Populations, feeding ecology and molt of Steller's Eiders

This study considers the temporal and spatial distribution of Steller's Eiders ( Polysticta stelleri ) during molt along the north side of the Alaska Peninsula from Port Heiden to Bechevin Bay. Subadult eiders molted primarily at Nelson Lagoon, adult males at Nelson Lagoon and Izembek Bay, and adult females primarily at Izembek Bay. Only a few eiders used Bechevin Bay, Seal Islands, and Port Heiden. Although the flightless period overlapped among different age and sex classes, subadults were flightless first, then adult males, and last, adult females. Eiders maintained spatial and temporal separation during the flightless period, thereby reducing competition for food resources. Eiders at Nelson Lagoon were observed feeding only by head-dipping during the pre-flightless period in 1979, a significant change from 1977 when they fed both by diving and dipping. During both 1977 and 1979 eiders foraged for approximately equal amounts of time during each stage of molt. Foods consisted primarily of bivalve mollusks and amphipods. These foods were consumed in different proportions before and after the wing-feather molt, with mussels being most important when eiders were growing remiges. Comparisons between the amount of energy in blue mussels ( Mytilus edulis ), clams ( Macoma balthica ), and gammarid amphipods showed that mussels yield the most energy per gram of whole wet weight. Apparently Steller's Eiders have adjusted to the increased energy demands of molt by eating invertebrates with high caloric content, rather than by increasing the amount of time feeding.

Alaska↗

Thermally induced chronic developmental stress in coho salmon: Integrating measures of mortality, early growth and fluctuating asymmetry

Developmental stability, or homeostasis, facilitates the production of consistent phenotypes by buffering against stress. Fluctuating asymmetry is produced by developmental instability and is manifested as small random departures from bilateral symmetry. Increased fluctuating asymmetry is thought to parallel compromised fitness, in part, because stress promotes energy dissipation. Compensatory energy expenditures within the organism are required to complete development, thus promoting instability through reductions in homeostasis. Increased heterozygosity may enhance developmental stability by reducing energy dissipation from stress through increased metabolic efficiency, possibly by providing greater flexibility in metabolic pathways. Traditionally, fluctuating asymmetry has been used as a bioindicator of chronic stress, provided that selective mortality of less fit individuals did not reduce stress-mediated increases in fluctuating asymmetry to background levels produced by natural developmental error, or create data inconsistencies such as higher asymmetry in groups exposed to lower stress. Unfortunately, absence of selective mortality and its effects, while often assumed, can be difficult to substantiate. We integrated measures of early growth, mortality, fluctuating asymmetry (mandibular pores, pectoral finrays, pelvic finrays, and gillrakers on the upper and lower arms of the first branchial arch) and directional asymmetry (branchiostegal rays) to assess chronic thermal stress (fluctuating temperatures as opposed to ambient temperatures) in developing eggs from two different coho salmon (Oncorhynchus kisutch) stocks and their reciprocal hybrids. Hybridization provided insight on the capacity of heterozygosity to reduce stress during development. Although egg losses were consistently higher in crosses exposed to fluctuating temperatures, egg mortality was predominantly a function of maternal stock of origin. Post-hatch losses were higher in crosses exposed to ambient temperatures than in crosses exposed to fluctuating temperatures during embryogenesis. Observed patterns of early growth revealed no heterosis, but instead reflected maternal effects, with some crosses slowing growth and yolk utilization when exposed to fluctuating temperatures. Analyses of fluctuating asymmetry also showed no effects from heterosis. While analyses of composite asymmetry scores and branchiostegal rays were inconclusive, analyses of individual characters showed significantly higher fluctuating asymmetry in pelvic finray counts and a marginal change in the numbers of fish asymmetric for this character in crosses exposed to chronic thermal stress. In contrast, the fluctuating asymmetry in lower gillraker counts was significantly higher in crosses exposed to ambient temperatures and there were significantly more fish asymmetric for this character. Data on mortalities and fluctuating asymmetry indicate pelvic finray development was thermally stressed, while the heightened fluctuating asymmetry in lower gillraker counts under ambient temperatures was due to a greater frequency of less fit fish that had not been culled by thermal stress. Changes in early growth patterns in response to developmental stress yielded no parallel responses in meristic characters. We conclude that chronic thermal stress produced both selectively lethal and sublethal effects that directly shaped fluctuating asymmetry and fitness profiles in these crosses. Implicit in this conclusion is that developmental instability analyses can detect more than just chronic sublethal stress, thus providing substantial credence for using instability studies as proactive bioassessment methodologies.

Oikos↗

Effect of hibernation and reproductive status on body mass and condition of coastal brown bears

We investigated the effect of hibernation and reproductive status on changes in body mass and composition of adult female brown bears (Ursus arctos) on the Kenai Peninsula, Alaska. This information is fundamental to understanding nutritional ecology of wild brown bear populations. Six adult females handled in the fall and following spring (paired samples) lost 73 &plusmn; 22 kg (x̄ &plusmn; SD; 32 &plusmn; 10%) of fall body mass over 208 &plusmn; 19 days. Of this mass loss, 56 &plusmn; 22% (55 &plusmn; 22 kg) was lipid and 44 &plusmn; 22% (43 &plusmn; 21 kg) was lean body mass. Catabolism of lipid stores accounted for 88.4 &plusmn; 8.1% of the body energy used to meet maintenance demands. Overwinter differences in body composition of adult females assessed only once in either the fall (n = 21) or spring (n = 32) were similar to those of paired samples. Relative fatness of bears entering the den was positively related to the contribution of fat (%) to body mass (P < 0.01) and body energy (P < 0.01) losses during hibernation. Thus, relative fatness at the onset of fasting influences the relative proportion of lipid stores and lean body mass catabolized to meet protein and energy demands during hibernation. In the spring, lone females had greater body and lean masses than females with cubs of the year or yearlings. Lipid content was greatest in lone females in the fall. Studies using body mass and composition as indices of population health should consider season or reproductive class.

Journal of Wildlife Management↗

Solid-solution aqueous-solution equilibria: Thermodynamic theory and representation

Thorstenson and Plummer's (1977) "stoichiometric saturation' model is reviewed, and a general relation between stoichiometric saturation Kss constants and excess free energies of mixing is derived for a binary solid-solution B1-xCxA: GE = RT[ln Kss - xln(xKCA) - (l-x)ln((l-x)KBA)]. This equation allows a suitable excess free energy function, such as Guggenheim's (1937) sub-regular function, to be fitted from experimentally determined Kss constants. Solid-phase free energies and component activity-coefficients can then be determined from one or two fitted parameters and from the endmember solubility products KBA and KCA. A general form of Lippmann's (1977,1980) "solutus equation is derived from an examination of Lippmann's (1977,1980) "total solubility product' model. Lippmann's II or "total solubility product' variable is used to represent graphically not only thermodynamic equilibrium states and primary saturation states but also stoichiometric saturation and pure phase saturation states.

American Journal of Science↗

United States Geological Survey Yearbook, fiscal year 1980

It is not very often that a single event is so overwhelming that it changes public perceptions of natural hazards for generations. Perhaps for the U.S. Geological Survey, the explosive volcanic activity of Mount St. Helens began such a change. After 101 years of careful science of the Earth's past and meticulous observations and assessments of the present, predictive earth science was in full public view. However vague and faint the glimpse of the future made possible by earth science, it was enough. Warnings were issued, thousands of lives were saved, and the age of real-time geology began. The Survey's basic mission has not changed, but the power of our analytical tools has increased by several orders of magnitude. The Survey's efforts to understand Earth processes and hydrologic principles continued with the collection, during fiscal year 1980, of valuable new data on the geologic origin and framework, seismicity, and mineral and energy resources of the United States. The Survey is also responsible for classification of the leasable minerals on Federal lands and the regulation of mineral exploration and development activities on Federal and Indian lands. As the principal earth science fact-gathering agency, the Survey provides information for sound decisionmaking by government and private industry. Industry uses the Survey's information in exploring for energy and minerals and improving their efforts to make development of energy and minerals compatible with environmental protection standards. Government uses the Survey's information in conducting leasing operations on public lands, in regulating the safe design and siting of nuclear plants, and in establishing guidelines for determining and locating areas that are subject to geologic hazards such as landslides, earthquakes, and volcanic eruptions. The Yearbook reports a broad range of the Survey's accomplishments during the past fiscal year and provides an overview of future directions. Many of the topics covered will continue to be important natural resource and earth science issues of the 1980's.

Yearbook↗

Assessment of lunar resource exploration in 2022

The idea of mining the Moon, once purely science-fiction, is now on the verge of becoming reality. Taking advantage of the resources on the Moon is part of the plans of many nations and some enterprising commercial entities; demonstrating in-situ (in place) resource utilization near the lunar south pole is an explicit goal of the United States’ Artemis program. Economic extraction and sustainable management of these resources require understanding the nature, quantity, and quality of each resource. This publication aims to provide a relatively simple, but technically rigorous, assessment of the status of lunar resource exploration in 2022. Building on the experience of the U.S. Geological Survey in conducting resource assessments for Earth, we propose a general methodology for quantitative lunar resources assessments. Lunar resources can be categorized as energy, mineral, and water and classified with respect to their certainty and their recoverability. The portion of the technically recoverable resource that can be converted to a commodity within budgetary and other mission constraints can be classified as a “reserve.” For energy resources, solar energy is known to be especially abundant along some high ridges near the lunar poles and the technology to exploit it is mature. Mineral resources, largely in the form of loose rock powder that covers the surface of the Moon, are also widely accessible in large quantities. Many different technologies to convert this material into useful commodities (such as landing pads and oxygen) are currently being developed and are likely to be available for industrial-scale application within 30 years. Water ice almost certainly exists in the polar regions of the Moon but there are fundamental unanswered questions about when and how the ice formed—leaving us without knowledge of the form, quantity, quality, and distribution of lunar ice. Until rover missions bring new ground truth data, lunar ice will remain a highly speculative resource that may be both limited and non-renewable.

Circular↗

Mineral resource management of the Outer Continental Shelf : leasing procedures, evaluation of resources, and supervision of production operations on leased lands of the Outer Continental Shelf

An important function of the Geological Survey is the evaluation and management of the mineral resources of the Outer Continental Shelf, particularly with respect to oil and gas, salt, and sulfur. Production of oil and gas from the Outer Continental Shelf of the United States has increased substantially over the past 20 years and represents an increasing percentage of total United States production. As discovery of major onshore production of oil and gas has become more difficult, the search has moved into the surrounding waters where submerged sedimentary formations are conducive to the accumulation of oil and gas. Increased energy demands of recent years have accelerated the pace of offshore operations with a corresponding improvement in technology as exploration and development have proceeded farther from shore and into deeper water. While improved technology and enforcement of more stringent regulations have made offshore operations safer, it is unrealistic to believe that completely accident-free operations can ever be achieved. Only slightly more than six percent of the world's continental terrace is adjacent to the United States, but less than one percent has been explored for oil and gas. Since the lead time for the development of offshore oil and gas resources can be as much as a decade, they do not provide an immediate energy supply but should be viewed in the light of a near-term source with a potential of becoming a medium-range source of supply pending the development of alternative energy sources. Revenues from the Outer Continental Shelf are deposited to the general fund of the United States Treasury. A major portion of these funds is allocated to the Land and Water Conservation Fund, the largest Federal grant-in-aid program of assistance to States, counties, and cities for the acquisition and development of public parks, open space, and recreation lands and water.

Circular↗

Sedimentary properties of shallow marine cores collected in June and September 2006, Hanalei Bay, Kaua'i, Hawai'i

Sedimentary facies, short-lived isotopes 7 Be, 137 Cs, and 210 Pb, and magnetic properties of sediment cores in Hanalei Bay, Kaua‘i, Hawai‘i, were used to assess sediment sources and patterns of deposition associated with seasonal flooding of the Hanalei River. Sediment cores were collected from the seafloor in June and September of 2006 to supplement similar data collected during the summer of 2005. The youngest and thickest terrigenous sediment was observed on the east side of the bay: near the Hanalei River mouth and in a bathymetric depression, known locally as the Black Hole, that acts as a temporary sediment sink. Deposits from floods that occurred between February and April 2006 left flood deposits in the eastern bay that, by June of 2006, were on the order of 10 cm thick. A flood occurred on August 7, 2006, that was smaller than floods that occurred the previous winter but was a substantial discharge event for the summer season. Deposits from the winter 2006 floods continued to dominate the sedimentary record in the eastern bay through early fall, even after the addition of newer sediment during the August 7 flood; this is consistent with the much higher sediment input of the winter floods compared with the August 7 flood. Broad variations in magnetic grain size and relative magnetite-hematite abundance in several sediment cores indicate many sources of upland terrigenous sediment. As a group, recent flood deposits show much less variation in these properties compared with older deposits, implying either that the 2006 winter–spring flood sediment originated from one or more distinct upland settings, or that substantial mixing of sediment from multiple sources occurred during transport. Sediment is most readily remobilized and advected out of the bay during winter, when oceanic conditions are energetic. In summer, wave and current measurements made concurrently with this study showed weak currents and little wave energy, indicating that sediment delivered during summer floods most likely remains in the bay until winter storms can remove it. Increased turbidity and sedimentation on corals resulting from floods of the Hanalei River could affect the sustainability of coral reefs and their many associated species. This possibility is of particular concern during summer months when wave energy is low and sediment is not readily remobilized and transported out of the bay. The timing (seasonality) and magnitude of sediment input to the coastal ocean relative to seasonal variations in wave and current energy could have significant ecological consequences for coral-reef communities in the Hawaiian Islands.

Hawai'i↗

Archive of digital boomer and CHIRP seismic reflection data collected during USGS field activity 08LCA03 in Lake Panasoffkee, Florida, May 2008

In May of 2008, the U.S. Geological Survey (USGS) conducted geophysical surveys in Lake Panasoffkee, located in central Florida, as part of the USGS Lakes and Coastal Aquifers (LCA) study. This report serves as an archive of unprocessed digital boomer and Compressed High Intensity Radar Pulse (CHIRP)* seismic reflection data, trackline maps, navigation files, Field Activity Collection System (FACS) logs, Geographic Information System (GIS) files, and formal Federal Geographic Data Committee (FGDC) metadata. Filtered and gained (a relative increase in signal amplitude) digital images of the seismic profiles and geospatially corrected interactive profiles are also provided. Refer to the Acronyms page for expansions of acronyms and abbreviations used in this report. *Due to poor data acquisition conditions associated with the lake bottom sediments, only two CHIRP tracklines were collected during this field activity. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). Example SU processing scripts and USGS software for viewing the SEG-Y files (Zihlman, 1992) are provided. The USGS Florida Integrated Science Center (FISC) - St. Petersburg assigns a unique identifier to each cruise or field activity. For example, 08LCA03 tells us the data were collected in 2008 for the Lakes and Coastal Aquifers (LCA) study and the data were collected during the third field activity for that study in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the field activity ID. The naming convention used for each seismic line is as follows: yye##a, where 'yy' are the last two digits of the year in which the data were collected, 'e' is a 1-letter abbreviation for the equipment type (for example, b for boomer and c for CHIRP), '##' is a 2-digit number representing a specific track, and 'a' is a letter representing the section of a line if recording was prematurely terminated or rerun for quality or acquisition problems. The boomer plate is an acoustic energy source that consists of capacitors charged to a high voltage and discharged through a transducer in the water. The transducer is towed on a sled floating on the water surface and, when discharged, emits a short acoustic pulse, or shot, which propagates through the water, sediment column, or rock beneath. The acoustic energy is reflected at density boundaries (such as the seafloor, sediment, or rock layers beneath the seafloor), detected by the receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.5 s) and recorded for specific intervals of time (for example, 100 ms). In this way, a two-dimensional (2-D) vertical profile of the shallow geologic structure beneath the ship track is produced. Figure 1 displays the boomer acquisition geometry. The EdgeTech SB-424 CHIRP system used for this survey has a vertical resolution of 4 - 8 cm, a penetration depth that is usually less than 2 m beneath the seafloor, and uses a signal of continuously varying frequency. The towfish is a sound source and receiver, which is typically towed 2 - 5 m above the seafloor. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by a receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.125 s) and recorded for specific intervals of time (for example, 50 ms); the resulting profile is a two-dimensional vertical image of the shallow geologic structure beneath the ship track. Figure 2 displays the acquisition geometry for the CHIRP system. Refer to table 1 for a summary of acquisition parameters and table 2 for trackline statistics.

Florida↗

Biological and ecological science for Nevada—The Silver State

Nevada is rich in minerals, energy, rangelands, mountains, deserts, lakes, fish, and wildlife. Many enterprises critical to Nevada's economy are based on natural resources including solar energy, livestock production, hunting, fishing, and other outdoor recreation. Nevada is a national leader in both geothermal and solar utility-scale energy production, and invested more than $ 1.2 million in 2016 in solar development alone. Agriculture, primarily livestock production, generates more than half a billion dollars annually, and wildlife watching, hunting, and fishing contribute more than $1 billion to Nevada's economy annually.

Nevada↗

Geohydrology of the shallow aquifers in the Greeley-Nunn area, Colorado

Urban areas commonly rely on ground water for at least part of the municipal water supply, and as population increases, urban areas expand and require larger volumes of water. However, the expansion of an urban area can reduce ground-water availability. This may occur through processes of depletion (withdrawal of most of the available ground water), degradation (chemicals used in the urban area seep into the ground and contaminate the ground water), and preemption (cost or restrictions on pumping ground water from under extensively urbanized areas may be prohibitive). Thus, a vital natural resource needed to support the growth of an urban area and its infrastructure can become less available because of growth itself. The diminished availability of natural resources caused by expansion of urban areas is not unique to water resources. For example, large volumes of aggregate (sand and gravel) are used in concrete and asphalt to build and maintain the infrastructure (buildings, roads, airports, and so forth) of an urban area. Yet, mining of aggregate commonly is preempted by urban expansion; for example, it cannot be mined from under a subdivision. Energy resources such as coal, oil, and natural gas likewise are critical to the growth and vitality of an urban area but may become less available as an urban area expands and preempts mining and drilling. In 1996, the U.S. Geological Survey began work on a national initiative designed to provide information on the availability of those natural resources (water, minerals, energy, and biota) that are critical to maintaining the Nation's infrastructure or that may become less available because of urban expansion. The initiative began with a 3-year demonstration project to develop procedures for assessing resources and methods for interpreting and publishing information in digital and traditional paper formats. The Front Range urban corridor of Colorado was chosen as the demonstration area (fig. 1), and the project was titled the Front Range Infrastructure Resources Project (FRIRP). This report and those of Robson (1996), Robson and others (1998), and Robson and others (2000a, 2000b, 2000c) are the results of FRIRP water-resources investigations; reports pertaining to geology, minerals, energy, biota, and cartography of the FRIRP are published separately. The water resources studies of the FRIRP were undertaken in cooperation with the Colorado Department of Natural Resources, Division of Water Resources. and the Colorado Water Conservation Board.

Hydrologic Atlas↗

Geohydrology of the shallow aquifers in the Fort Collins-Loveland area, Colorado

Urban areas commonly rely on ground water for at least part of the municipal water supply, and as population increases, urban areas expand and require larger volumes of water. However, the expansion of an urban area can reduce ground-water availability. This may occur through processes of depletion (withdrawal of most of the available ground water), degradation (chemicals used in the urban area seep into the ground and contaminate the ground water), and preemption (cost or restrictions on pumping ground water from under extensively urbanized areas may be prohibitive). Thus, a vital natural resource needed to support the growth of an urban area and its infrastructure can become less available because of growth itself. The diminished availability of natural resources caused by expansion of urban areas is not unique to water resources. For example, large volumes of aggregate (sand and gravel) are used in concrete and asphalt to build and maintain the infrastructure (buildings, roads, airports, and so forth) of an urban area. Yet, mining of aggregate commonly is preempted by urban expansion; for example, it cannot be mined from under a subdivision. Energy resources such as coal, oil, and natural gas likewise are critical to the growth and existence of an urban area but may become less available as an urban area expands and preempts mining and drilling. In 1996, the U.S. Geological Survey began work on a national initiative designed to provide information on the availability of those natural resources (water, minerals, energy, and biota) that are critical to maintaining the Nation's infrastructure or that may become less available because of urban expansion. The initiative began with a 3-year demonstration project to develop procedures for assessing resources and methods for interpreting and publishing information in digital and traditional paper formats. The Front Range urban corridor of Colorado was chosen as the demonstration area (fig. 1), and the project was titled the Front Range Infrastructure Resources Project (FRIRP). This report and those of Robson (1996), Robson and others (1998), and Robson and others (2000a, 2000b, 2000c) are the results of FRIRP water-resources investigations; reports pertaining to geology, minerals, energy, biota, and cartography of the FRIRP are published separately. The waterresources studies of the FRIRP were undertaken in cooperation with the Colorado Department of Natural Resources, Division of Water Resources, and the Colorado Water Conservation Board.

Hydrologic Atlas↗

Geohydrology of the shallow aquifers in the Fort Lupton-Gilcrest area, Colorado

Urban areas commonly rely on ground water for at least part of the municipal water supply, and as population increases, urban areas expand and require larger volumes of water. However, the expansion of an urban area can reduce ground-water availability. This may occur through processes of depletion (withdrawal of most of the available ground water), degradation (chemicals used in the urban area seep into the ground and contaminate the ground water), and preemption (cost or restrictions on pumping ground water from under extensively urbanized areas may be prohibitive). Thus, a vital natural resource needed to support the growth of an urban area and its infrastructure can become less available because of growth itself. The diminished availability of natural resources caused by expansion of urban areas is not unique to water resources. For example, large volumes of aggregate (sand and gravel) are used in concrete and asphalt to build and maintain the infrastructure (buildings, roads, airports, and so forth) of an urban area. Yet, mining of aggregate commonly is preempted by urban expansion; for example, it cannot be mined from under a subdivision. Energy resources such as coal, oil, and natural gas likewise are critical to the growth and existence of an urban area but may become less available as an urban area expands and preempts mining and drilling. In 1996, the U.S. Geological Survey began work on a national initiative designed to provide information on the availability of those natural resources (water, minerals, energy, and biota) that are critical to maintaining the Nation's infrastructure or that may become less available because of urban expansion. The initiative began with a 3-year demonstration project to develop procedures for assessing resources and methods for interpreting and publishing information in digital and traditional paper formats. The Front Range urban corridor of Colorado was chosen as the demonstration area (fig. 1), and the project was titled the Front Range Infrastructure Resources Project (FRIRP). This report and those of Robson (1996), Robson and others (1998), and Robson and others (2000a, 2000b, 2000c) are the results of FRIRP water-resources investigations; reports pertaining to geology, minerals, energy, biota, and cartography of the FRIRP are published separately. The water resources studies of the FRIRP were undertaken in cooperation with the Colorado Department of Natural Resources, Division of Water Resources, and the Colorado Water Conservation Board.

Colorado↗