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

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At least 487 records · Page 27Linked to original sources
USGS2006

An integrated monitoring approach using multiple reference sites to assess sustainable restoration in coastal Louisiana

Achieving sustainable resource management in coastal Louisiana requires establishing reference conditions that incorporate the goals and objectives of restoration efforts. Since the reference condition is usually considered sustainable, it can be a gauge to assess the present condition of a (degraded) system or to evaluate progress of management actions toward some target system state (the reference or desired conditions). In 2003, the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) Task Force and the Louisiana State Wetlands Authority adopted the “Coastwide Reference Monitoring System -- Wetlands” (CRMS--Wetlands) for Louisiana. This system will provide data from multiple reference sites to explore the properties of a sustained reference condition. CRMS--Wetlands provides links between project-specific and system-wide objectives, criteria for selecting reference sites or conditions, a more robust statistical design, and critical monitoring variables. In addition, a system-wide assessment and monitoring plan (SWAMP) is being developed that incorporates and evaluates existing monitoring efforts (to the extent possible) within a system-wide experimental design. The SWAMP will integrate monitoring of biological, chemical, physical, and climatological variables in four modules: wetlands (CRMS--Wetlands), barrier islands, inshore waters and rivers, and nearshore coastal waters. Data and information collected under SWAMP will contribute to developing a systems-synthesis model for coastal Louisiana. Regional restoration project leaders in coastal Louisiana acknowledge the mutual dependence of monitoring and modeling the coastal landscape. For example, experiments or measurements should not be conducted independently of modeling and vice versa. Assessment should be directed at reducing scientific uncertainty to improve confidence in modeling and monitoring tools and ultimately to assist management actions. An adaptive environmental assessment and management process prescribes modeling, monitoring, and research activities to be conducted from initial stages of restoration planning to optimize the ability to assess and achieve sustainable restoration.

Louisiana↗
USGS2003

Hydraulic logging methods - A summary and field demonstration in Conyers, Rockdale County, Georgia

Geophysical surveying techniques provide important information for ground-water investigations (Zohdy and others, 1974; Keys, 1997; Haeni and others, 2001). Subsurface-geophysical methods are used to delineate and characterize hydraulically active zones; the extent of contamination, and contaminant sources; identify geologic features; optimize monitoring well placement; and guide remediation efforts. Borehole-geophysical methods provide information about the physical, chemical, and hydraulic properties of rock, sediments, and fluids in the subsurface and provide important information on subsurface bedrock structures including lithology, rock fabric, location, orientation, and hydraulic properties of fractures (Keys, 1990). Effective use of geophysical data requires that the data be interpreted in the context of known local and regional geology and hydrogeology. In addition, because of the complexity and heterogeneity of crystalline-rock aquifers, a suite of borehole geophysical methods is used to determine the location, extent, and nature of fractures and other structural features in the bedrock aquifer. The geophysical data from each borehole and method are analyzed together to provide an integrated interpretation, thereby reducing the ambiguity that can occur by interpreting each geophysical log individually (Shapiro and others, 1999). Previous work using borehole geophysics to characterize ground-water availability in crystalline rock aquifers includes Chapman and Lane (1996), Mack and others (1998), and Johnson and others (1999). Other investigations that focused on contamination in fractured-rock aquifers used geophysical methods to relate highly transmissive features to structural features in the bedrock (Hansen and Lane, 1995; and Lane and others, 2002).

Georgia↗
USGS1967

Standards for water quality

The quality which is necessary depends on the use to which the water will be put. Because uses vary, so also must quality standards. Maintaining any level of quality presents a problem of cost and depends on variations in natural water characteristics, in time and space, and variations in volume and types of wastes. For quality standards appropriate to a given water body, hydrologic network data can provide duration curves of flow, concentrations of dissolved oxygen, dissolved solids, including nutrients (nitrates and phosphates), turbidity, temperature, and other significant chemical, physical, and biological parameters. Standards can then be expressed as occurrences in percentage of time or with respect to flow.

Conference Paper↗
USGS2001

Paleoclimate concepts

Interpretation of paleoclimate records requires an understanding of Earth’s climate system, the causes (forcings) of climate changes, and the processes that amplify (positive feedback) or damp (negative feedback) these changes. Paleoclimatologists reconstruct the history of climate from proxies, which are those characteristics of sedimentary deposits that preserve paleoclimate information. A great range of physical, chemical, isotopic, and biological characteristics of lake and ocean sediments, ice cores, cave formations, tree rings, the land surface itself, and more are used to reconstruct past climate. Ages of climate events are obtained by counting annual layers, measuring effects of the decay of radioactive atoms, assessing other changes that accumulate through time at rates that can be assessed accurately, and using time-markers to correlate sediments with others that have had their ages measured more accurately. Not all questions about the history of Earth’s climate can be answered through paleoclimatology: in some cases the necessary sediments are not preserved, or the climatic variable of interest is not recorded in the sediments. Nonetheless, many questions can be answered from the available information. An overview of the history of Arctic climate during the past 65 million years (m.y.) shows a long-term irregular cooling for tens of millions of years. As ice became established in the Arctic, it grew and shrank for tens of thousands of years in regular cycles. During at least the most recent of these cycles, shorter lived, large, and rapid fluctuations occurred, especially around the North Atlantic Ocean. The last 11,000 years or so have remained generally warm and relatively stable, but with small climate changes of varying spacing and size. Assessment of the causes of climate changes, and the records of those causes, shows that reduction in atmospheric carbon-dioxide concentration and changes in continental positions were important in the cooling trend throughout tens of millions of years. The cycling in ice extent was paced by features of Earth’s orbit and amplified by the effects of the ice itself, changes in carbon dioxide and other greenhouse gases, and additional feedbacks. Abrupt climate changes were linked to changes in the circulation of the ocean and the extent of sea ice. Changes in the Sun’s output and in Earth’s orbit, volcanic eruptions, and other factors have contributed to the natural climate changes since the end of the last ice age.

Book chapter↗
USGS1974

Correlation between geophysical data and rock types in the Piedmont and coastal plain of northeast Virginia and related areas

Physical, chemical, and mineralogic characteristics of rock units in parts of the northeast Virginia Piedmont are reflected in the aeromagnelic, aeroradioactivity, and gravity data for this area. Magnetic anomalies show the areal distribution of rocks containing magnetite. Aeroradiometric anomalies in the Piedmont and Coastal Plain provinces are directly related to the K 2 O content of the formations. In the crystalline rocks of the Piedmont this is reflected in their muscovite and microcline content, whereas in the Coastal Plain province it is related to the glauconite content of the Aquia Formation. Locally, in the crystalline rocks of the Piedmont, uranium- and thorium-bearing mineral content is of greater importance than K 2 O-bearing mineral content in producing aeroradiometric anomalies. The region also is characterized by (1) a northern gravity high, (2) a southern gravity high presumed to be caused by mafic rocks, and (3) an intervening zone characterized by low gravity relief and underlain by schist and gneiss. Geologic and geophysical extrapolation southward toward the Arvonia area show that the Chopawamsic Formation and the volcanic rocks of the Evington group are coeval. Also, on the northwest side of these volcanic rocks is a belt of small rootless mafic and ultramafic rocks diapirically ceplaced in folded rocks of Early Cambrian (?) age.

Virginia↗
USGS2023

Achieving water quality goals in the Chesapeake Bay: A comprehensive evaluation of system response

A Comprehensive Evaluation of System Response Achieving Water Quality Goals in the Chesapeake Bay: A Comprehensive Evaluation of System Response (CESR) includes an evaluation of why progress toward meeting the TMDL and water quality standards has been slower than expected and offers options for how progress can be accelerated. This report is a summation of a three year investigation into the 40 year effort to reduce nutrient loads to Chesapeake Bay. History The effort began as a STAC independent initiative in March 2019, after Kurt Stephenson, Zach Easton, and Brian Benham proposed the idea of a report that would identify gaps and uncertainties in system response—physical, chemical, biological, and socioeconomic—that impact efforts designed to attain water quality standards in Chesapeake Bay. As STAC Chair at the time, Benham facilitated the development of a collaborative process that would engage the entire committee. As a first step in approaching the long causal chain that links management actions to their eventual impact on water quality and living resources, workgroups were formed around the subsystems of this chain: nutrient and sediment reductions (watershed), water quality response to nutrient and sediment reductions (estuary) and living resource response to water quality (living resources). Each of these workgroups generated an independent document with a self-determined scope (i.e., workgroups were afforded flexibility to address issues beyond the original objectives). Because the content of each document was both unique and substantial, STAC chose to publish them as stand-alone documents with authorship attribution. In the second step, a steering committee developed a series of framing questions to guide the preparation of this report that would meet the objective of identifying gaps and uncertainties in achieving the Bay TMDL and water quality standards. Coeditors Stephenson and Wardrop, supported to great extent by a subgroup of the Steering Committee (Leonard Shabman, Zach Easton, Jeremy Testa, William Dennison, Kenny Rose, and Mark Monaco) were tasked with assembling ideas and contributions to write a single draft text, drawing material from the aforementioned resource documents, STAC and Chesapeake Bay Program reports, the scientific literature, and a limited amount of additional analyses performed in collaboration with Bay Program scientists. The resulting report was then submitted for several reviews by both steering committee members and the membership at-large to produce a consensus report.

Maryland, Virginia↗
USGS2000

Europa's Crust and Ocean: Origin, Composition, and the Prospects for Life

We have considered a wide array of scenarios for Europa's chemical evolution in an attempt to explain the presence of ice and hydrated materials on its surface and to understand the physical and chemical nature of any ocean that may lie below. We postulate that, following formation of the jovian system, the europan evolutionary sequence has as its major links: (a) initial carbonaceous chondrite rock, (b) global primordial aqueous differentiation and formation of an impure primordial hydrous crust, (c) brine evolution and intracrustal differentiation, (d) degassing of Europa's mantle and gas venting, (e) hydrothermal processes, and (f) chemical surface alteration. Our models were developed in the context of constraints provided by Galileo imaging, near infrared reflectance spectroscopy, and gravity and magnetometer data. Low-temperature aqueous differentiation from a carbonaceous CI or CM chondrite precursor, without further chemical processing, would result in a crust/ocean enriched in magnesium sulfate and sodium sulfate, consistent with Galileo spectroscopy. Within the bounds of this simple model, a wide range of possible layered structures may result; the final state depends on the details of intracrustal differentiation. Devolatilization of the rocky mantle and hydrothermal brine reactions could have produced very different ocean/crust compositions, e.g., an ocean/crust of sodium carbonate or sulfuric acid, or a crust containing abundant clathrate hydrates. Realistic chemical-physical evolution scenarios differ greatly in detailed predictions, but they generally call for a highly impure and chemically layered crust. Some of these models could lead also to lateral chemical heterogeneities by diapiric upwellings and/or cryovolcanism. We describe some plausible geological consequences of the physical-chemical structures predicted from these scenarios. These predicted consequences and observed aspects of Europa's geology may serve as a basis for further analys is and discrimination among several alternative scenarios. Most chemical pathways could support viable ecosystems based on analogy with the metabolic and physiological versatility of terrestrial microorganisms. ?? 2000 Academic Press.

Icarus↗
USGS1994

Hydrologic data from the study of acidic contamination in the Miami Wash-Pinal Creek area, Arizona, water years 1992-93

Since 1984, hydrologic data have been collected as part of a U.S. Geological Survey study of the occurrence and movement of acidic contamination in the aquifer and streams of the Pinal Creek drainage basin near Globe, Arizona. Ground-water data from that study are presented for water years 1992 and 1993 and include location, construction information, site plans, water levels, chemical and physical field measurements, and selected chemical analyses of water samples for 10 monitoring well groups. During January 1993, a flood occurred in Pinal Creek that resulted in a record peak discharge of 5,700 cubic feet per second. During this flood, well group 450 was destroyed. Surface-water data are presented for 13 sites and include discharge measurements, chemical and physical field measure- ments, and chemical analyses of water. Data from a solute-transport study that was conducted in November 1992 are presented for shallow ground-water and surface-water sites along Pinal Creek. During this study, variations in metal chemistry with distance along Pinal Creek and depth below the streambed were determined and two filter sizes were used to quantify the partitioning of metals between dissolved and particulate phases. Monthly precipi- tation data and long-term precipitation statistics are presented for two sites.

Arizona↗
USGS1975

Water resources data for Washington, water year 1974; Part 2, Water quality records

Water resources data for the 1974 water year for Washington include records of data for the chemical and physical characteristics of surface and ground water. Water-quality data on chemical, physical, and biological characteristics of surface and ground water were collected from designated sampling sites at predetermined intervals such as once daily, weekly, monthly or less frequently, and at some sites data were recorded on punched paper tape at 15-, 30-, or 60 minute intervals. Records are given for 157 sampling stations of which 149 are continuous record stations and 8 are miscellaneous sites. Records of chemical analyses also are given for 19 ground-water sites. Locations of the continuous-record sampling stations are shown in figure 1. A few pertinent stations (not included above) in bordering States are also included. The records were collected by the Water Resources Division of the U.S. Geological Survey under the direction of L. B. Laird, district chief. These data represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Washington.

Washington↗
USGS1979

Radioactive springs geochemical data related to uranium exploration: basic data and use of multivariate factor scores

Radioactive springs and wells at 33 localities in the States of Colorado, Utah, Arizona, and New Mexico have been studied and sampled to obtain geochemical data to determine whether such data are useful in a uranium exploration program. Most samples were collected from mineral-rich springs probably related to hydrothermal systems of various ages. Two sets of data were obtained, the first based on the chemical composition and physical and chemical properties of spring and ground water, and the second based on the chemical composition of mineral precipitates deposited by radioactive springs. Multivariate statistical analysis of the water data suggests four major geochemical factors affecting the 23 parameters measured. These factors were labeled as total dissolved solids, alkalinity, temperature, and Fe-U concentration. Multivariate statistical analysis of the precipitate data suggests five factors affecting the 32 element values measured. These factors were labeled as mineral contamination, Mn precipitation, Fe-As-Be precipitation, heavy metals precipitation, and Ba-Ra precipitation. Relative intensities of the geochemical processes represented by the factors were computed using factor scores. Sample localities were ranked on the basis of relative intensities, and the five localities with the highest intensities were selected as being the most favorable for more intensive exploration for uranium. Immediate use of such selection would be experimental because of the lack of industry experience at this time in the exploration of active hydrothermal systems for uranium.

Open-File Report↗
USGS1977

Evaluation of chemical, biological, and physical conditions in the Winter Haven chain of lakes, Florida, March-June 1976

Reconnaissance of water-quality conditions of 14 interconnected navigable lakes, in and around Winter Haven, Fla., revealed that in March and May, 1976 most were eutrophic, on the basis of high nutrient (nitrogen and phosphorus) concentrations. Lakes Lulu and Shipp were the most enriched as a result of surface runoff from residential, agricultural, and highly urbanized areas, and many years of municipal and industrial waste effluent input. Phytoplankton counts were greater than a million cells per milliliter in some lakes sampled; algal blooms have ocurred, and water clarity was low. The level of Lake Howard fell to the lowest stage recorded in 31 years during May 1976. The record low was likely due to rainfall deficiency. Leakage of water through the lake beds to the ground-water system is also possible, but determination of the escaping water volume would require additional study. (Woodard-USGS)

Florida↗