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At least 307 records · Page 17Linked to original sources
USGS2016

Ecological resilience

Resilience is the capacity of complex systems of people and nature to withstand disturbance without shifting into an alternate regime, or a different type of system organized around different processes and structures (Holling, 1973). Resilience theory was developed to explain the non-linear dynamics of complex adaptive systems, like social-ecological systems (SES) (Walker & Salt, 2006). It is often apparent when the resilience of a SES has been exceeded as the system discernibly changes, such as when a thriving city shifts into a poverty trap, but it is difficult to predict when that shift might occur because of the non-linear dynamics of complex systems. Ecological resilience should not be confused with engineering resilience (Angeler & Allen, 2016), which emphasizes the ability of a SES to perform a specific task consistently and predictably, and to re-establish performance quickly should a disturbance occur. Engineering resilience assumes that complex systems are characterized by a single equilibrium state, and this assumption is not appropriate for complex adaptive systems such as SES. In the risk governance context this means that compounded perturbations derived from hazards or global change can have unexpected and highly uncertain effects on natural resources, humans and societies. These effects can manifest in regime shifts, potentially spurring environmental degradation that might lock SES in an undesirable system state that can be difficult to reverse, and as a consequence economic crises, conflict, human health problems.

Book chapter↗
USGS2019

Windows to the deep 2018: Exploration of the southeast US Continental margin

Windows to the Deep 2018: Exploration of the Southeast US Continental Margin was a 36-day expedition aboard NOAA Ship Okeanos Explorer to acquire data on priority exploration areas identified by the ocean management and scientific communities. This expedition involved high-resolution multibeam sonar mapping and ROV dives, ranging from 340 m to 3,400 m depth, across the southeast US continental margin. Operations primarily targeted areas with potential to host deep-sea coral and sponge communities, including mounds, ridges, and terraced features on the continental slope. Dive sites also included maritime heritage sites, a submarine landslide feature, and several submarine canyon slopes, some of which exhibited evidence of active cold seeps. High biological abundance was noted at six of 17 dive sites, three of which also had high biological diversity. Additionally, deep-sea corals or sponges were observed on every dive except one, which was dedicated to gas seep exploration.

Atlantic Ocean, Blake Plateau, Stetson Mesa↗
USGS2012

Elevation uncertainty in coastal inundation hazard assessments

Coastal inundation has been identified as an important natural hazard that affects densely populated and built-up areas (Subcommittee on Disaster Reduction, 2008). Inundation, or coastal flooding, can result from various physical processes, including storm surges, tsunamis, intense precipitation events, and extreme high tides. Such events cause quickly rising water levels. When rapidly rising water levels overwhelm flood defenses, especially in heavily populated areas, the potential of the hazard is realized and a natural disaster results. Two noteworthy recent examples of such natural disasters resulting from coastal inundation are the Hurricane Katrina storm surge in 2005 along the Gulf of Mexico coast in the United States, and the tsunami in northern Japan in 2011. Longer term, slowly varying processes such as land subsidence (Committee on Floodplain Mapping Technologies, 2007) and sea-level rise also can result in coastal inundation, although such conditions do not have the rapid water level rise associated with other flooding events. Geospatial data are a critical resource for conducting assessments of the potential impacts of coastal inundation, and geospatial representations of the topography in the form of elevation measurements are a primary source of information for identifying the natural and human components of the landscape that are at risk. Recently, the quantity and quality of elevation data available for the coastal zone have increased markedly, and this availability facilitates more detailed and comprehensive hazard impact assessments.

Book chapter↗
USGS2017

Reply to comments of Nolan and Cook

The following reply to the comments by Nolan and Cook makes the following points. The Palmer Drought Severity Index (PDSI) is not a measure of summer rainfall. Cahokia's "Big Bang" dates to the end of the Edelhardt phase and continued through the Lohmann phase. The "American Bottom" refers only to the Mississippi River floodplain in the vicinity of East St. Louis, and the exact nature of human response to climate change cannot be predicted from PDSI data alone.

American Antiquity↗
USGS2018

Ecosystems, Ecosystem Services, and Biodiversity

Biodiversity —the variety of life on Earth—provides vital services that support and improve human health and well-being. Ecosystems, which are composed of living things that interact with the physical environment, provide numerous essential benefits to people. These benefits, termed ecosystem services, encompass four primary functions: provisioning materials, such as food and fiber; regulating critical parts of the environment, such as water quality and erosion control; providing cultural services, such as recreational opportunities and aesthetic value; and providing supporting services, such as nutrient cycling. Climate change poses many threats and potential disruptions to ecosystems and biodiversity, as well as to the ecosystem services on which people depend. Building on the findings of the Third National Climate Assessment (NCA3), this chapter provides additional evidence that climate change is significantly impacting ecosystems and biodiversity in the United States. Mounting evidence also demonstrates that climate change is increasingly compromising the ecosystem services that sustain human communities, economies, and well-being. Both human and natural systems respond to change, but their ability to respond and thrive under new conditions is determined by their adaptive capacity, which may be inadequate to keep pace with rapid change. Our understanding of climate change impacts and the responses of biodiversity and ecosystems has improved since NCA3. The expected consequences of climate change will vary by region, species, and ecosystem type. Management responses are evolving as new tools and approaches are developed and implemented; however, they may not be able to overcome the negative impacts of climate change. Although efforts have been made since NCA3 to incorporate climate adaptation strategies into natural resource management, significant work remains to comprehensively implement climate-informed planning. This chapter presents additional evidence for climate change impacts to biodiversity, ecosystems, and ecosystem services, reflecting increased confidence in the findings reported in NCA3. The chapter also illustrates the complex and interrelated nature of climate change impacts to biodiversity, ecosystems, and the services they provide.

Report↗
USGS1996

Trouble in paradise: The brown tree snake in the western Pacific

The brown treesnake (Boiga irregularis) was recognized as a pest species by Congress in Section 1209 of the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 (NANPCA). Like aquatic pests, tree snakes are sometimes dispersed by ships, have wide-ranging effects on natural and human communities, and threaten to spread to other areas. The problems they are causing on Guam, a formerly snake-free island, are unusual in that they involve many aspects of the biota of Guam and directly affect the human residents of the island.

Aquatic Nuisance Species Digest↗
USGS1991

National Water-Quality Assessment (NAWQA) program. A basis for water-resource policy development

The concepts that are the basis for the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program began forming in the early 1980's. By 1986, a pilot phase was initiated to test and refine assessment concepts and in 1991, the NAWQA program began a multi-year transition to a fully operational program. The goals of the program are to describe the status and trends in the quality of a large representative part of the Nation's ground- and surface-water resources and to develop an understanding of the natural and human factors affecting the quality of these resources. This information will provide a sound scientific basis upon which water resources decision making at all governmental levels can be based. To meet its goals, the program will integrate water-quality information at local, regional, and national scales. The program will be perennial and consist of two major components -- study-unit investigations and national assessment activities. Investigations of surface- and ground-water resources of major regional hydrologic systems (river basins and aquifer systems) each covering 1200 to about 60,000 square miles, will be conducted on a rotating basis for 60 study units located throughout the Nation. Key findings from these study-unit investigations will be used along with other information to provide issue-oriented water-quality assessments of regional and national interest.

Conference Paper↗
USGS2012

Using integrated research and interdisciplinary science: Potential benefits and challenges to managers of parks and protected areas

Our purpose in this paper is to build a case for utilizing interdisciplinary science to enhance the management of parks and protected areas. We suggest that interdisciplinary science is necessary for dealing with the complex issues of contemporary resource management, and that using the best available integrated scientific information be embraced and supported at all levels of agencies that manage parks and protected areas. It will take the commitment of park managers, scientists, and agency leaders to achieve the goal of implementing the results of interdisciplinary science into park management. Although such calls go back at least several decades, today interdisciplinary science is sporadically being promoted as necessary for supporting effective protected area management(e.g., Machlis et al. 1981; Kelleher and Kenchington 1991). Despite this history, rarely has "interdisciplinary science" been defined, its importance explained, or guidance provided on how to translate and then implement the associated research results into management actions (Tress et al. 2006; Margles et al. 2010). With the extremely complex issues that now confront protected areas (e.g., climate change influences, extinctions and loss of biodiversity, human and wildlife demographic changes, and unprecedented human population growth) information from more than one scientific discipline will need to be brought to bear in order to achieve sustained management solutions that resonate with stakeholders (Ostrom 2009). Although interdisciplinary science is not the solution to all problems, we argue that interdisciplinary research is an evolving and widely supported best practice. In the case of park and protected area management, interdisciplinary science is being driven by the increasing recognition of the complexity and interconnectedness of human and natural systems, and the notion that addressing many problems can be more rapidly advanced through interdisciplinary study and analysis.

The George Wright Forum↗
USGS2011

Developing climate data records and essential climate variables from landsat data

The series of Landsat missions has compiled the longest record of satellite observation of the Earth’s land surface, extending for more than 38 years for most areas of the globe. Landsat data are particularly important as long term climate data records because the scale of observation is sufficient to differentiate between natural and human drivers of land cover change. The USGS has established consistent radiometric calibration across the Landsat TM and ETM+ sensors, and have extended the calibration back to the earlier MSS sensors. The USGS is developing capabilities to create fundamental climate data records (FCDRs), thematic climate data records (TCDRs), and essential climate variables (ECVs) from the Landsat data archive. Two high priority TCDRs were identified: surface reflectance and land surface temperature because they have direct application or are required as input to the generation of ECVs. We will focus development on a few of the terrestrial ECVs that have a high potential for being derived from Landsat data, that include land cover, albedo, fire disturbance, surface water, snow and ice, and leaf area index (LAI). We are collaborating with scientists who have demonstrated successful algorithm development and application of these science products to develop a framework of processing capabilities to support research projects and land management applications, along with an independent strategy for product validation. Our goal is to scale the creation and validation of these products from specific sites in the conterminous U.S. and Alaska, for extension to continental and global scales.

Conference Paper↗
USGS2006

Coping with climate change

What have we learned so far about how climate change is affecting our global environment? Studies show that it adversely affects human and natural systems by • reducing biodiversity • altering hydrological systems • impairing biological and chemical cycles • making it more difficult to restore degraded ecosystems Climate is not the only factor in the deterioration of natural systems.We are making big changes to the landscape, altering land use and land cover in major ways. These changes combined present a challenge to environmental management. Adaptive management is a scientific approach to managing the adverse impacts of climate and landscape change.

ActionBioscience↗
USGS2007

Procedures for the salvage and necropsy of the dugong (Dugong dugon)

Data and specimens collected from dugong carcasses and live stranded individuals provide vital information for research and management agencies. The ability to assign a cause of death (natural and/or human induced) to a carcass assists managers to identify major threats to a population in certain areas and to evaluate and adapt management measures. Data collected from dugong carcasses have contributed to research in areas such as life history, feeding biology, investigating the stock structure/genetics of dugongs, contaminants studies, heavy metal analyses, parasitology, and the effects of habitat change. Adapted from the 'Manual of Procedures for the Salvage and Necropsy of Carcasses of the West Indian Manatee (Trichechus manatus),' this manual provides a detailed guide for dugong (Dugong dugon) carcass handling and necropsy procedures. It is intended to be used as a resource and training guide for anyone involved in dugong incidents who may lack dugong expertise.

Book↗
USGS2001

Quality of water in alluvial aquifers in eastern Iowa

The goal of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program is to assess the status and trends in the quality of the Nation's surface and ground water, and to better understand the natural and human factors affecting water quality. The Eastern Iowa Basins study unit encompasses an area of about 50,500 square kilometers (19,500 square miles) in eastern Iowa and southern Minnesota and is one of 59 study units in the NAWQA program. Land-use studies are an important component of the NAWQA program, and are designed to assess the concentration and distribution of water-quality constituents in recently recharged ground water associated with the most significant land use and hydrogeologic settings within a study unit. The focus of the land-use study in the Eastern Iowa Basins study unit is agricultural and urban land uses and alluvial aquifers. Agriculture is the dominant land use in the study unit. Urban areas, although not extensive, represent important potential source areas of contaminants associated with residential, commercial, and industrial activities. Alluvial aquifers are present throughout much of the study unit, and constitute a major ground-water supply that is susceptible to contamination from land-use activities. Ground-water samples were collected from monitoring wells at 31 agricultural and 30 urban sites in the Eastern Iowa Basins study unit during June-August 1997 to evaluate the effects of land use and hydrogeology on the water quality of alluvial aquifers. Calcium, magnesium, and bicarbonate were the dominant ions in most samples and were likely derived from solution of carbonate minerals (calcite and dolomite) present in alluvial detrital deposits. Tritium-based ages indicate ground water was most likely recharged after the 1950's at all but one sampling site. Agricultural and urban land-use areas have remained relatively stable in the study area since the 1950's, therefore the effects of current land use should be reflected in ground water sampled during this study. Sodium and chloride concentrations were significantly higher in samples from urban areas, where roads are more numerous and road salts may be more frequently applied, than in agricultural areas. Nitrate was detected in 94 percent of samples from agricultural areas and 77 percent of samples from urban areas. Nitrate concentrations were significantly higher in agricultural areas than in urban areas and exceeded the U.S. Environmental Protection Agency maximum contaminant level for drinking water (10 milligrams per liter as N) in 39 percent of samples from agricultural areas. Nitrate concentrations in samples from urban areas did not exceed the maximum contaminant level. Greater usage of fertilizers in agricultural areas most likely contributes to higher nitrate concentrations in samples from those areas. Pesticides were detected in 84 percent of samples from agricultural areas and 70 percent from urban areas. Atrazine and metolachlor were the most frequently detected pesticides in samples from agricultural areas; atrazine and prometon were the most frequently detected pesticides in samples from urban areas. None of the pesticide concentrations exceeded U.S. Environmental Protection Agency maximum contaminant levels or lifetime health advisories for drinking water. Pesticide degradates were detected in 94 percent of samples from agricultural areas and 53 percent from urban areas. Metolachlor ethane sulfonic acid and deethylatrazine were the most frequently detected metabolites in samples from agricultural areas; metolachlor ethane sulfonic acid and alachlor ethane sulfonic acid were the most frequently detected degradates in samples from urban areas. Total degradate concentrations were significantly higher in samples from agricultural areas than in samples from urban areas. Total pesticide concentrations (parent compounds) tended to be higher in samples from agricultural areas; however, this difference was not statistically significant. Degradates constituted the major portion of the total residue concentration in the alluvial aquifer. Volatile organic compounds were detected in 40 percent of samples from urban areas and 10 percent from agricultural areas. Methyl tert-butyl ether was the most commonly detected volatile organic compound and was present in 23 percent of samples from urban areas. Elevated concentrations (greater than 30 micrograms per liter) of methyl tert-butyl ether and BTEX compounds (benzene, toluene, ethylbenzene, and xylene) in two samples from urban areas suggest the possible presence of point-source gasoline leaks or spills. Factors other than land use may contribute to observed differences in water quality between and within agricultural and urban areas. Nitrate, atrazine, deethylatrazine, and deisopropylatrazine concentrations were significantly higher in shallow wells with sample intervals nearer the water table and in wells with thinner cumulative clay thickness above the sample intervals, suggesting that longer flow paths allow for greater residence time and increase opportunities for sorbtion, degradation, and dispersion which may contribute to decreases in nutrient and pesticide concentrations with depth. Nitrogen speciation was influenced by redox conditions. Nitrate concentrations were significantly higher in ground water with dissolved-oxygen concentrations in excess of 0.5 milligrams per liter. Ammonia concentrations were higher in ground water with dissolved-oxygen concentrations of 0.5 milligrams per liter or less, however, this relation was not statistically significant. The amount of available organic matter may limit denitrification rates. Elevated nitrate concentrations (greater than 2.0 mg/L) were significantly related to lower dissolved organic carbon concentrations in water samples from both agricultural and urban areas. A similar relation between nitrate concentrations (in water) and organic carbon concentrations (in aquifer material) also was observed but was not statistically significant.

Iowa↗
USGS2000

Summary of the major water-quality findings from the Eastern Iowa Basins study unit of the National Water-Quality Assessment Program

An integrated assessment of the water quality in streams and aquifers in the Wapsipinicon, Iowa, Cedar, and Skunk River basins was conducted in 1996 through 1998 as part of the Eastern Iowa Basins (EIWA) study unit of the U.S. Geological Survey's National Water-Quality Assessment Program (NAWQA). The EIWA study unit is one of 59 study units across the Nation designed to assess the status and trends in the quality of the Nation's ground- and surface-water resources and to link the status and trends with an understanding of the natural and human factors that affect the quality of water. Over 90 percent of the land in the EIWA study unit is used for agricultural purposes, while forested areas account for only 4 percent and urban areas about 2 percent of the land. Surface-water samples were collected monthly and during selected storm events from six sites in medium-sized basins (125 to about 400 mi2) and five sites in large river basins (2,300 to 12,500 mi2). The medium-sized basins were selected to be representative of various physical features, hydrogeology, and agricultural landuse (row crops and concentrated animal feeding operations) that may affect water quality. The large river sites were selected to determine the integrated effects of combinations of landuse and hydrogeology on river-water quality. Ground-water samples were collected primarily from the alluvial aquifers because of the aquifers' direct hydraulic connection with rivers and streams and because alluvial aquifers are one of the most important sources for domestic, municipal, and industrial water supplies in the study area. Monitoring wells were installed in agricultural and urban areas of the alluvial aquifers to assess the quality of the most recently recharged water in relation to land use. Existing domestic wells screened in alluvial aquifers and the Silurian/Devonian aquifer were sampled to assess deeper and older ground water. Surface- and ground-water samples were analyzed for a wide variety of chemical constituents (major ions, nutrients, and pesticides) commonly associated with agricultural and urban activities. Because they were not expected to occur in rivers and streams, volatile organic compounds (VOC's), commonly comprising fuels, solvents, and other industrial compounds were only analyzed in ground-water samples. The age of the ground water, important information needed to relate ground-water quality to land use, was determined using both tritium and chlorofluorocarbons (Freon?) age-dating methods. Results from the EIWA NAWQA study build on previous and ongoing research and water-quality monitoring programs in Iowa and provide new insights into the relation between the quality of the State's water resources and human activities. The major findings from the study are listed below.

Iowa↗
USGS2000

Estimating the impacts of oil spills on polar bears

The polar bear is the apical predator and universal symbol of the Arctic. They occur throughout the Arctic marine environment wherever sea ice is prevalent. In the southern Beaufort Sea, polar bears are most common within the area of the outer continental shelf, where the hunt for seals along persistent leads and openings in the ice. Polar bears are a significant cultural and subsistence component of the lifestyles of indigenous people. They may also be one of the most important indicators of the health of the Arctic marine environment. Polar bears have a late age of maturation, a long inter0brth period, and small liter sizes. These life history features make polar bear populations susceptible to natural and human perturbations. Petroleum exploration and extraction have been in progress along the coast of northern Alaska for more than 25 years. Until recently, most activity has taken place on the mainland or at sites connected to the shore by a causeway. In 1999, BP Exploration-Alaska began constructing the first artificial production island designed to transport oil through sub-seafloor pipelines. Other similar projects have been proposed to begin in the next several years. The proximity of oil exploration and development to principal polar bear habitats raises concerns, and with the advent of true off-shore development projects, these concerns are compounded. Contact with oil and other industrial chemicals by polar bears, through grooming, consumption of tainted food, or direct consumption of chemicals, may be lethal. The active ice where polar bears hunt is also where spilled oil may be expected to concentrate during spring break-up and autumn freeze-up. Because of this, we could expect that an oil spill in the waters and ice of the continental shelf would have profound effects on polar bears. Assessments of the effects of spills, however, have not been done. This report described a promising method for estimating the effects of oil spills on polar bears in the Arctic marine environment. It uses enough real data to illuminate necessary calculations and illustrate the value of the methods. The results and conclusions presented here are only examples of possible scenarios resulting from a new estimation method. Final assessment of the potential impacts to polar bears of an oil spill remains a work in progress.

Alaska, Northwest Territories, Yukon↗
USGS2004

Seafloor habitat mapping and classification in Glacier Bay, Alaska: Phase 1 & 2 1996-2004

Glacier Bay is a diverse fjord ecosystem with multiple sills, numerous tidewater glaciers and a highly complex oceanographic system. The Bay was completely glaciated prior to the 1700’s and subsequently experienced the fastest glacial retreat recorded in historical times. Currently, some of the highest sedimentation rates ever observed occur in the Bay, along with rapid uplift (up to 2.5 cm/year) due to a combination of plate tectonics and isostatic rebound. Glacier Bay is the second deepest fjord in Alaska, with depths over 500 meters. This variety of physical processes and bathymetry creates many diverse habitats within a relatively small area (1,255 km 2 ). Habitat can be defined as the locality, including resources and environmental conditions, occupied by a species or population of organisms (Morrison et al 1992). Mapping and characterization of benthic habitat is crucial to an understanding of marine species and can serve a variety of purposes including: understanding species distributions and improving stock assessments, designing special management areas and marine protected areas, monitoring and protecting important habitats, and assessing habitat change due to natural or human impacts. In 1996, Congress recognized the importance of understanding benthic habitat for fisheries management by reauthorizing the Magnuson-Stevens Fishery Conservation and Management Act and amending it with the Sustainable Fisheries Act (SFA). This amendment emphasizes the importance of habitat protection to healthy fisheries and requires identification of essential fish habitat in management decisions. Recently, the National Park Service’s Ocean Stewardship Strategy identified the creation of benthic habitat maps and sediment maps as crucial components to complete basic ocean park resource inventories (Davis 2003). Glacier Bay National Park managers currently have very limited knowledge about the bathymetry, sediment types, and various marine habitats of ecological importance in the Park. Ocean floor bathymetry and sediment type are the building blocks of marine communities. Bottom type and shape affects the kinds of benthic communities that develop in a particular environment as well as the oceanographic conditions that communities are subject to. Accurate mapping of the ocean floor is essential for park manager’s understanding of existing marine communities and will be important in assessing human induced changes (e.g., vessel traffic and commercial fishing), biological change (e.g., rapid sea otter recolonization), and geological processes of change (e.g., deglaciation). Information on animal-habitat relationships, particularly within a marine reserve framework, will be valuable to agencies making decisions about critical habitats, marine reserve design, as well as fishery management. Identification and mapping of benthic habitat provides National Park Service mangers with tools to increase the effectiveness of resource management. The primary objective of this project is to investigate the geological characteristics of the biological habitats of halibut, Dungeness crab, king crab, and Tanner crab within Glacier Bay National Park. Additionally, habitat classification of shallow water regions of Glacier Bay will provide crucial information on the relationship between benthic habitat features and the abundance of benthic prey items for a variety of marine predators, including sea ducks, the rapidly increasing population of sea otters, and other marine mammals.

Alaska↗
USGS2020

New operational national satellite burned area product

Introduction Lack of consistent spatial and temporal fire information with relevant spatial resolution hinders land management and broad-scale assessments of fire activity, especially in the eastern United States and the Great Plains where fi re is important ecologically and culturally. Remote sensing can be used to monitor fi re activity, augment existing fi re data, and fill information gaps. In particular, Landsat offers one of the most complete time series of remote sensing data sets as the Landsat satellites with spectral bands useful for mapping fi res and burn severity have been operational since 1984. Furthermore, Landsat satellite imagery collect data at a resolution useful for on-the-ground comparisons and management decisions. Methods A gradient-boosting regression model algorithm was used to predict burn probabilities (BP), indicating the likelihood that a pixel had burned in a fire. Then the algorithm translated the burn probability images to burn classification (BC) images using thresholding and region growing. Burned areas smaller than 5 acres were removed to reduce noise. The BP and BC products were generated for Landsat scenes collected from 1984 to present with <= 80% cloud cover and are available for download from USGSs EarthExplorer website (www.earthexplorer. usgs.gov). Annual summaries were also produced from the scene-level BC and BP products. These include: 1) the maximum burn probability value from all scenes in a year, (2) the burn classification count, or the number of times a pixel was classified as burned in a year, (3) the burn date, or the day of year of the first Landsat scene a pixel was classified as burned, and (4) a burn classification which removes burned areas still visible from previous years with a filter. Results The Landsat Burned Area Products identified 183% more burned area than the Monitoring Trends in Burn Severity and 56% more burned area than the MODIS MCD64A1.006 products2. From 1984 through 2018, annual burned area mapped by the Landsat Burned Area Products averaged 30,000 km2, ranged between 14,000 km2 in 1991 and 46,500 km2 in 2012, and increased over time at a rate of 356 km2/year. The Landsat Burned Area products consistently map burned areas 5 acres or larger over time while capturing unburned islands within fi res. Such characteristics are critical for understanding long-term impacts of fi res on human and natural systems. The products are being routinely produced as new Landsat data are collected and demonstrate the utility remote sensing offers for monitoring landscape change.

Report↗
USGS2010

Conceptual understanding and groundwater quality of selected basin-fill aquifers in the Southwestern United States

The National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey has been conducting a regional analysis of water quality in the principal aquifer systems in the southwestern United States (hereinafter, “Southwest”) since 2005. Part of the NAWQA Program, the objective of the Southwest Principal Aquifers (SWPA) study is to develop a better understanding of water quality in basin-fill aquifers in the region by synthesizing information from case studies of 15 basins into a common set of important natural and human-related factors found to affect groundwater quality. The synthesis consists of three major components: 1. Summary of current knowledge about the groundwater systems, and the status of, changes in, and influential factors affecting quality of groundwater in basin-fill aquifers in 15 basins previously studied by NAWQA (this report). 2. Development of a conceptual model of the primary natural and human-related factors commonly affecting groundwater quality, thereby building a regional understanding of the susceptibility and vulnerability of basin-fill aquifers to contaminants. 3. Development of statistical models that relate the concentration or occurrence of specific chemical constituents in groundwater to natural and human-related factors linked to the susceptibility and vulnerability of basin-fill aquifers to contamination. Basin-fill aquifers occur in about 200,000 mi 2 of the 410,000 mi 2 SWPA study area and are the primary source of groundwater supply for cities and agricultural communities. Four of the principal aquifers or aquifer systems of the United States are included in the basin-fill aquifers of the study area: (1) the Basin and Range basin-fill aquifers in California, Nevada, Utah, and Arizona; (2) the Rio Grande aquifer system in New Mexico and Colorado; (3) the California Coastal Basin aquifers; and (4) the Central Valley aquifer system in California. Because of the generally limited availability of surface-water supplies in the arid to semiarid climate, cultural and economic activities in the Southwest are particularly dependent on supplies of good-quality groundwater. Irrigation and public-supply withdrawals from basin-fill aquifers in the study area account for about one quarter of the total withdrawals from all aquifers in the United States. Many factors influence the quality of groundwater in the 15 case-study basins, but some common factors emerge from the basin summaries presented in this report. These factors include the chemical composition of the recharge water, consolidated rock geology and composition of aquifer materials derived from consolidated rock, and land and water use. The major water-quality issues in many of the developed case-study basins are increased concentrations of dissolved solids, nitrate, and VOCs in groundwater as a result of human activities. The information presented and the citations listed in this report serve as a resource for those interested in the groundwater-flow systems in the NAWQA case-study basins. The summaries of water-development history, hydrogeology, conceptual understanding of the groundwater system under both predevelopment and modern conditions, and effects of natural and human-related factors on groundwater quality presented in the sections on each basin also serve as a foundation for the synthesis and modeling phases of the SWPA regional study.

Arizona, California, Colorado, Nevada, New Mexico,↗
USGS2008

The Global Flows of Metals and Minerals

This paper provides a preliminary review of the trends in worldwide metals and industrial minerals production and consumption based on newly developed global metals and minerals Material Flow Accounts (MFA). The MFA developed encompass data on extraction and consumption for 25 metal and mineral commodities, on a country-by-country and year-by-year basis, for the period 1970 to 2004. The data-base, jointly developed by the authors, resides with the U.S. Geological Survey (USGS) as individual commodity Excel workbooks and within a Filemaker data management system for use in analysis. Numerous national MFA have been developed to provide information on the industrial metabolism of individual countries. These MFA include material flows associated with the four commodity categories of goods that are inputs to a country's economy, agriculture, forestry, metals and minerals, and nonrenewable organic material. In some cases, the material flows associated with the creation and maintenance of the built infrastructure (such as houses, buildings, roads, airports, dams, and so forth) were also examined. The creation of global metals and industrial minerals flows is viewed as a first step in the creation of comprehensive global MFA documenting the historical and current flows of all of the four categories of physical goods that support world economies. Metals and minerals represent a major category of nonrenewable resources that humans extract from and return to the natural ecosystem. As human populations and economies have increased, metals and industrial minerals use has increased concomitantly. This dramatic growth in metals and minerals use has serious implications for both the availability of future resources and the health of the environment, which is affected by the outputs associated with their use. This paper provides an overview of a number of the trends observed by examining the database and suggests areas for future study.

Open-File Report↗