SEARCH · Geology Reports

Results for “Environmental Development”

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

SourceResearch connectionFrom yearThrough year

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

At least 1,603 records · Page 89Linked to original sources

USGS2022

Use case development for earth monitoring, analysis, and prediction (EarthMAP)—A road map for future integrated predictive science at the U.S. Geological Survey

Executive Summary The U.S. Geological Survey (USGS) 21st-century science strategy 2020–30 promotes a bureau-wide strategy to develop and deliver an integrated, predictive science capability that works at the scales and timelines needed to inform societally relevant resource management and protection and public safety and environmental health decisions (U.S. Geological Survey, 2021). This is the overarching goal of the USGS Earth Monitoring, Analysis, and Prediction (EarthMAP) vision, which consists of three components: (1) integrated data and information, (2) integrated predictive science, and (3) actionable information—all designed and delivered to respond to user needs. To launch this vision and help shape the design and implementation of integrated predictive science, the USGS Regional Offices each developed a set of use cases (hereafter Use Cases)—short descriptions of potential science applications that could clearly address high priority decision-making needs of our stakeholders and that align with an integrated science focus. Use Cases are not actionable science planning documents, nor stand-alone scholarly works, but should be considered as innovative, next-generation science ideas that can be considered as potential components of science plans still under development. The goal of Use Case development was to (1) identify and characterize existing USGS scientific capacities and expertise that can support science goals and products, (2) identify opportunities to leverage current capacities for next-generation science, and (3) foster engagement across the entire Bureau to further refine the USGS strategy for EarthMAP and integrated predictive science. The Use Case development effort documented in this report was coordinated by the Use Case Development Team (UCDT), consisting of representatives from each region. The UCDT undertook five tasks: (1) develop a unified approach to engage bureau scientists consistently across all regions in aspirational thinking about what can be accomplished; (2) work with the regions and their Science Centers to generate an initial set of Use Cases, authored directly by scientists; (3) characterize, summarize, and document the initial set of Use Case submissions from authors to illuminate bureau-level demand for integrated science; (4) compare existing and needed capacities from the Use Case descriptions with preliminary results of the EarthMAP Capacity Assessment (Keisman and others, 2021); and (5) describe lessons learned from the Use Case development process and provide recommendations to inform future efforts to generate integrated science activities. This report outlines the approach the UCDT developed to solicit Use Cases from the regions and summarizes the high-level qualitative findings from this first-round effort. The UCDT received 36 Use Cases from the regions and identified potential points of convergence and commonalities considered useful in making connections among the participating scientists. The Southwest (SW) Region and the Rocky Mountain (RM) Region asked scientists to give special consideration to Use Cases with applicability to the Colorado River Basin, and seven of the Use Cases specifically named that geographic area as a focus. Coastal hazards and coastal resilience were identified in Use Cases from the Alaska (AK), Northeast (NE), and Southeast (SE) Regions. Aspects of wildfire and post-wildfire response were part of Uses Cases from AK, RM, and SW Regions. The greatest convergence of Use Case themes was related to conservation of public lands and waters, which is a powerful linkage lending strength to future collaborative efforts. The most common type of stakeholder decisions that would be informed by the Use Case science applications were related to adaptation, mitigation, and response (for example, how to increase the resilience of coastal communities to climate-related stressors and how to prevent or respond to harmful algal blooms). Other common types of decisions included water and land management decisions (including operational water management decisions such as reservoir operations and land use planning in the sagebrush biome), decisions about how to manage and conserve habitats and species, and risk management decisions (such as managing the post-wildfire flood risks). These decision types are not exclusive because many Use Cases cross categories. Use Case authors identified existing and needed science and technology capabilities required for Use Case implementation, which were then aligned to capabilities assessed in the EarthMAP Capacity Assessment (Keisman and others, 2021). Strong alignment was found for data and information integration approaches, modeling and prediction approaches, and capabilities related to delivery of actionable information. A majority of Use Cases indicated insufficient current capacity for needed data collection methods, data integration, and modeling and prediction approaches, whereas only 25 percent indicated insufficient capacity for actionable information delivery. Overall, many Use Case capacity demand gaps could potentially be met by existing bureau-wide capacity. In addition, nearly half of the Use Cases could potentially be implemented within 3 years if funding, capabilities, and personnel impediments were removed and science priorities were realigned. Several challenges emerged during the Use Case development process. The first challenge was developing an approach that was flexible enough to accommodate regional differences in planning and implementation, while also ensuring enough guidance to promote meaningful summary analyses. The UCDT encountered a strong demand for continuous communication and education to improve overall understanding of the integrated predictive science strategy. Another challenge was managing expectations about EarthMAP activities as a design effort that was not aligned to an immediate funding opportunity. Connecting the Use Cases to stakeholder needs without the opportunity for direct stakeholder engagement was also challenging. The last notable challenge was in obtaining consistent interpretation and characterization of the qualitative data housed in the narrative descriptions of Use Cases, written in different styles. Overall, the 36 Use Cases can serve as components of a road map for advancing integrated monitoring and predictive science throughout the USGS by revealing opportunities to (1) encourage cross-region initiatives that address shared interests in common themes by integrating similar Use Cases and through direct involvement of stakeholders in identifying needs and designing effective responses, (2) leverage the Use Cases to target investments that are aligned with the Bureau and Department of the Interior (DOI) priorities, (3) connect Use Cases and the results of the companion EarthMAP Capacity Assessment (Keisman and others, 2021) to identify potential priorities for capacity building investments, and (4) raise awareness of common integrated and interdisciplinary science interests within and across the regions through Use Case and Capacity Assessment summary outreach activities.

Open-File Report↗

USGS2021

Annual winter water-level drawdowns influence physical habitat structure and macrophytes in Massachusetts, USA, lakes

Annual wintertime water-level drawdowns are a common management strategy in recreational lakes; however, few studies have estimated their relative impact on lake littoral habitat among a set of typically co-occurring anthropogenic stressors including lakeshore development and herbicide application. Within 21 Massachusetts, USA lakes that represented a drawdown magnitude gradient (0.07–2.26 m), we assessed depth-specific littoral habitat (coarse wood, sediment, macrophytes) at two sites adjacent to forested or developed shorelines. Using generalized linear mixed models, we found coarse wood abundance and branching complexity was not correlated with drawdown magnitude but was primarily explained by the presence of lakeshore development. Drawdown magnitude was negatively correlated with silt cover and positively correlated with coarse substrate cover, with effects further varying by depth (0.5 m vs. 1 m). Macrophyte biomass and biovolume were negatively correlated with drawdown magnitude with effects also varying by depth for biomass. Macrophyte taxa with annual longevity strategies (e.g., Najas flexilis ) and amphibious growth forms increased in biomass proportions with drawdown magnitude. Distance-based redundancy analyses suggested macrophyte taxa composition was driven by drawdown magnitude, coarse substrate, alkalinity, water transparency, and herbicide use. These results suggest the importance of water quality and depth on macrophyte assemblage responses to winter drawdowns and the potential to develop drawdown-tolerant macrophyte assemblages. Altogether, understanding the unique impacts of anthropogenic stressors on littoral zone habitat across heterogeneous environmental lake conditions can help minimize impacts to lake ecological integrity while maintaining recreational value.

Massachusetts↗

USGS2019

Semiautomated process for enumeration of fishes from recreational-grade side-scan sonar imagery

The use of hydroacoustic techniques is increasing as scientists search for less invasive ways to monitor fish populations, and using recreational side‐scan sonar (SSS) imagery for monitoring has become more common in aquatic resource management over the last 15 years due in part to its low cost and user‐friendly interface. The time‐consuming nature of manually counting fish targets has limited the use of the data that is collected by these systems in research or management contexts. To reduce the time and effort that is required to enumerate acoustic targets that are presumed to be fish, we developed a semiautomated process that rapidly quantifies targets from recreational SSS imagery by using an open‐source image processing software. Perceived fish targets were enumerated using a set of macroinstructions that performed similarly to manual enumeration by three experienced assessors. This method reduced variation that arises from individual assessors and eliminated the prohibitive time constraints that are associated with manual processing. Herein, we describe how our semiautomated process could be used in fisheries management contexts after further research and development of sampling methods. Future research will focus on field validation, quantifying relative abundance, testing across a broader range of environmental conditions, and exploring other applications for fisheries management.N

North American Journal of Fisheries Management↗

USGS2024

Modeling the potential spread of the non-native regal demoiselle, Neopomacentrus cyanomos, in the western Atlantic

Predicting the potential distribution of a non-native species can assist management efforts to mitigate impacts on recipient ecosystems. However, such predictions are lacking for marine species, such as the non-native regal demoiselle, Neopomacentrus cyanomos , that is currently expanding its distribution in the western Atlantic. We used correlative species distribution models with three common algorithms to predict suitable habitat for N. cyanomos in the region. We compared models developed using native, non-native, and global occurrences to differentiate drivers across separate ranges using a suite of 12 environmental characteristics. While final models included an ensemble of variables, the majority ranked the combined effect of temperature variables as a key predictor correlated with the distribution of N. cyanomos. Habitat suitability increased as water temperatures increased beyond 16 °C and where annual thermal ranges were greater than 10 °C at the shallowest depth with substrate within a study cell (~ 9.2 km 2 resolution). Habitat suitability also increased where maximum surface temperatures were greater than 27 °C. In the non-native range, the proportion of reef available in each cell was another important variable increasing the suitable habitat for N. cyanomos . Our models predicted high habitat suitability for N. cyanomos throughout the Greater Caribbean, in higher latitudes along North and South American Atlantic coasts, in the eastern Pacific Ocean, and highlights key areas where managers can monitor and target potential removal efforts. The distribution of this non-native species is likely to continue expanding throughout the region with little known about potential implications on native communities.

Coral Reefs↗

USGS2012

Predicting biological condition in southern California streams

As understanding of the complex relations among environmental stressors and biological responses improves, a logical next step is predictive modeling of biological condition at unsampled sites. We developed a boosted regression tree (BRT) model of biological condition, as measured by a benthic macroinvertebrate index of biotic integrity (BIBI), for streams in urbanized Southern Coastal California. We also developed a multiple linear regression (MLR) model as a benchmark for comparison with the BRT model. The BRT model explained 66% of the variance in B-IBI, identifying watershed population density and combined percentage agricultural and urban land cover in the riparian buffer as the most important predictors of B-IBI, but with watershed mean precipitation and watershed density of manmade channels also important. The MLR model explained 48% of the variance in B-IBI and included watershed population density and combined percentage agricultural and urban land cover in the riparian buffer. For a verification data set, the BRT model correctly classified 75% of impaired sites (B-IBI < 40) and 78% of unimpaired sites (B-IBI = 40). For the same verification data set, the MLR model correctly classified 69% of impaired sites and 87% of unimpaired sites. The BRT model should not be used to predict B-IBI for specific sites; however, the model can be useful for general applications such as identifying and prioritizing regions for monitoring, remediation or preservation, stratifying new bioassessments according to anticipated biological condition, or assessing the potential for change in stream biological condition based on anticipated changes in population density and development in stream buffers.

California↗

USGS2001

Effects of thermal regime on ovarian maturation and plasma sex steroids in farmed white sturgeon, Acipenser transmontanus

Recently, commercial aquaculture farms in Northern California have exposed gravid, cultured white sturgeon females to cold water (12 ?? 1??C) throughout the late phase of vitellogenesis and ovarian follicle maturation resulting in improved ovulation rates and egg quality. However, the optimum timing for transfer of broodfish to the cold water and the capacity of transferred broodfish to maintain reproductive competence over an extended time in cold water had not been evaluated. Gravid white sturgeon females that have been raised at water temperatures of 16-20??C were transported to either cold water (12 ?? 1??C; Group 1) in November 1997 or maintained in ambient water temperatures (10-19??C; Group 2) until early spring. In March 1998, half of the fish in Group 2 had regressed ovaries, but the remaining females had intact ovarian follicles and were transported to the cold water. Ovarian follicles and blood were collected from females until they reached the stage of spawning readiness (determined by germinal vesicle position and an oocyte maturation assay) or underwent ovarian regression. Exposure of gravid sturgeon females to ambient water temperatures (14.5 ?? 2.3??C, mean ?? S.D.) from October to March led to a decrease in plasma sex steroids and a high incidence of ovarian regression in fish with a more advanced stage of oocyte development. Transfer of females with intact ovarian follicles to cold water (12 ?? 1??C) in the fall or early spring resulted in normal ovarian development in the majority of females. Holding females in cold water does not seem to override their endogenous reproductive rhythms but extends their capacity to maintain oocyte maturational competence over a longer period of time. A temperature-sensitive phase in ovarian development may occur during the transition from vitellogenic growth to oocyte maturation, and the degree and timing of sensitivity to environmental temperature are dependent on the female's endogenous reproductive rhythm. ?? 2001 Elsevier Science B.V. All Rights reserved.

Aquaculture↗

USGS2003

Fitting population models from field data

The application of population and community ecology to solving real-world problems requires population and community dynamics models that reflect the myriad patterns of interaction among organisms and between the biotic and physical environments. Appropriate models are not hard to construct, but the experimental manipulations needed to evaluate their defining coefficients are often both time consuming and costly, and sometimes environmentally destructive, as well. In this paper we present an empirical approach for finding the coefficients of broadly inclusive models without the need for environmental manipulation, demonstrate the approach with both an animal and a plant example, and suggest possible applications. Software has been developed, and is available from the senior author, with a manual describing both field and analytic procedures.

Ecological Modelling↗

USGS2021

Optical properties of water for prediction of wastewater contamination, human-associated bacteria, and fecal indicator bacteria in surface water at three watershed scales

Relations between spectral absorbance and fluorescence properties of water and human-associated and fecal indicator bacteria were developed for facilitating field sensor applications to estimate wastewater contamination in waterways. Leaking wastewater conveyance infrastructure commonly contaminates receiving waters. Methods to quantify such contamination can be time consuming, expensive, and often nonspecific. Human-associated bacteria are wastewater specific but require discrete sampling and laboratory analyses, introducing latency. Human sewage has fluorescence and absorbance properties different than those of natural waters. To assist real-time field sensor development, this study investigated optical properties for use as surrogates for human-associated bacteria to estimate wastewater prevalence in environmental waters. Three spatial scales were studied: Eight watershed-scale sites, five subwatershed-scale sites, and 213 storm sewers and open channels within three small watersheds (small-scale sites) were sampled (996 total samples) for optical properties, human-associated bacteria, fecal indicator bacteria, and, for selected samples, human viruses. Regression analysis indicated that bacteria concentrations could be estimated by optical properties used in existing field sensors for watershed and subwatershed scales. Human virus occurrence increased with modeled human-associated bacteria concentration, providing confidence in these regressions as surrogates for wastewater contamination. Adequate regressions were not found for small-scale sites to reliably estimate bacteria concentrations likely due to inconsistent local sanitary sewer inputs.

Michigan, New York, Ohio, Wisconsin↗

USGS2004

Effects of environmental change on groundwater recharge in the Desert Southwest

Climate and other environmental conditions have varied in the past, and will almost certainly vary significantly in the near future. The response of groundwater recharge to changes in environmental conditions is thus a matter of active concem for water-resources management. The major mechanisms for this response of recharge are three-fold. First, changes in vegetation communities can shift the water balance at the base of the root zone, increasing or decreasing the amount of recharge. Second, variations in the amount of runoff can affect channel recharge. Finally, shifts in the seasonality of precipitation can strongly affect the fraction that is evapotranspired back into the atmosphere and thus affect the amount that becomes recharge. Increases in recharge (defined as the water flux across the water table) may in some cases significantly increase fluxes through regional aquifers, but in other cases, depending on the hydrogeology, may only result in increased streamflow or evapotranspiration within the recharge area. Basins with relatively low maximum elevations, deep water tables, thin soils, and highly permeable recharge areas experience the largest recharge response to increases in precipitation. The relatively well-known paleoenvironmental history of the American Southwest can be compared with various lines of evidence for changes in recharge. These lines of evidence include timing of speleothem formation, chloride profiles in thick vadose zones, changes in water table shown by subsurface calcite precipitation, and expanded groundwater discharge areas. This evidence indicates that the wettest periods of the past 25 ka, which were generally between 20 and 13 ka, were also periods of enhanced vadose zone fluxes and aquifer discharge. Climate-driven changes in recharge appear to have been substantially mediated through changes in vegetation. This evidence for strong recharge response to past environmental changes indicates that expected future climate and environmental change will also cause changes in recharge. The ability to adequately predict future changes in recharge will depend on developing process-based numerical models that can simulate coupled climate/vegetation/ vadose zone processes and incorporate the outputs into groundwater/surface water models that can resolve processes at scales ranging from the hillslope to the basin.

Water Science and Application↗

USGS2000

Composition of fish communities in relation to stream acidification and habitat in the Neversink River, New York

The effects of acidification in lotic systems are not well documented. Spatial and temporal variability of habitat and water quality complicate the evaluation of acidification effects in streams and rivers. The Neversink River in the Catskill Mountains of southeastern New York, the tributaries of which vary from well buffered to severely acidified, provided an opportunity to investigate the extent and magnitude of acidification effects on fish communities of headwater systems. Composition of fish communities, water quality, stream hydrology, stream habitat, and physiographic factors were characterized from 1991 to 1995 at 16 first- to fourth-order sites in the basin. Correlation and regression analyses were used to develop empirical models and to assess the relations among fish species richness, total fish density, and total fish biomass and environmental variables. Chronic and episodic acidification and elevated concentrations of inorganic monomeric aluminum were common, and fish populations were rare or absent from several sites in the upper reaches of the basin; as many as six fish species were collected from sites in the lower reaches of the basin. Species distributions and species richness were most highly related to stream pH, acid-neutralizing capacity (ANC), inorganic monomeric aluminum (Al im ), calcium (Ca) 2+ , and potassium (K) + concentrations, site elevation, watershed drainage area, and water temperature. Fish density was most highly related to stream pH, Al im , ANC, K + , Ca 2+ , and magnesium (Mg) 2+ concentrations. Fish biomass, unlike species richness and fish density, was most highly related to physical habitat characteristics, water temperature, and concentrations of Mg 2+ and silicon. Acidity characteristics were of secondary importance to fish biomass at all but the most severely acidified sites. Our results indicate that (1) the total biomass of fish communities was not seriously affected at moderately to strongly acidified sites; (2) species richness and total density of fish were adversely affected at strongly to severely acidified sites; and (3) possible changes in competitive interactions may mitigate negative effects of acidification on fish communities in parts of the Neversink River Basin.

New York↗

USGS2012

Evaluating the predictive abilities of community occupancy models using AUC while accounting for imperfect detection

The ability to accurately predict patterns of species' occurrences is fundamental to the successful management of animal communities. To determine optimal management strategies, it is essential to understand species-habitat relationships and how species habitat use is related to natural or human-induced environmental changes. Using five years of monitoring data in the Chesapeake and Ohio Canal National Historical Park, Maryland, USA, we developed four multi-species hierarchical models for estimating amphibian wetland use that account for imperfect detection during sampling. The models were designed to determine which factors (wetland habitat characteristics, annual trend effects, spring/summer precipitation, and previous wetland occupancy) were most important for predicting future habitat use. We used the models to make predictions of species occurrences in sampled and unsampled wetlands and evaluated model projections using additional data. Using a Bayesian approach, we calculated a posterior distribution of receiver operating characteristic area under the curve (ROC AUC) values, which allowed us to explicitly quantify the uncertainty in the quality of our predictions and to account for false negatives in the evaluation dataset. We found that wetland hydroperiod (the length of time that a wetland holds water) as well as the occurrence state in the prior year were generally the most important factors in determining occupancy. The model with only habitat covariates predicted species occurrences well; however, knowledge of wetland use in the previous year significantly improved predictive ability at the community level and for two of 12 species/species complexes. Our results demonstrate the utility of multi-species models for understanding which factors affect species habitat use of an entire community (of species) and provide an improved methodology using AUC that is helpful for quantifying the uncertainty in model predictions while explicitly accounting for detection biases.

Ecological Applications↗

USGS2006

The Environmental Monitoring and Assessment Program (EMAP)-West: Summary of activities and accomplishments in South Dakota, 2000-2004

The Environmental Monitoring and Assessment Program (EMAP)-West was initiated in South Dakota in 2000 by the U.S. Environmental Protection Agency (USEPA). The two primary objectives of the surface waters component of EMAP-West were to (1) develop the monitoring tools (biological indicators, stream survey design, estimates of reference condition) necessary to produce unbiased estimates of the ecological condition of surface waters across a large geographic area of the West; and (2) demonstrate the effectiveness of those tools in a large-scale assessment. Although not specifically defined as an objective, data collected during EMAP-West also will help to establish a baseline for comparisons with data obtained from future monitoring efforts and could document changing biological conditions resulting from changing land-use or land-management practices associated with regulatory or restorative efforts. EMAP-West is a partnership between USEPA, States, Tribes, and other interested parties in USEPA Regions 8, 9, and 10. In South Dakota, the principle EMAP-West cooperators include the USEPA, South Dakota Department of Game, Fish and Parks (GF&P), and the U.S. Geological Survey (USGS). Other agencies such as the Natural Resource Conservation Service, the South Dakota Department of Environment and Natural Resources (SDDENR), State Conservation Districts, and various Tribal departments also have provided valuable expertise and assistance. This fact sheet summarizes the activities and accomplishments associated with EMAP-West in South Dakota during 2000–2004. Efforts were focused on perennial streams that usually can be waded. Large rivers also were assessed during EMAP-West under the auspices of USEPA using boats and similar techniques, but are not included in the activities discussed here. Data-collection activities for wadeable streams were conducted under the auspices of USEPA in South Dakota during 2000 and by the USGS during 2001–2004. A more detailed description of EMAP-West activities and assessments in South Dakota is available in Heakin and others ( in press ).

South Dakota↗

USGS2025

U.S. Geological Survey global seabed mineral resources

The U.S. Geological Survey (USGS) provides science and data on seabed mineral resources and ecosystems, as well as on the potential hazards associated with extraction. The Nation relies on minerals for infrastructure, technology, manufacturing, and energy production. Critical minerals are essential to the economic and national security of the United States and have a supply chain vulnerable to disruption. For decades, USGS scientific innovation has contributed to the delineation of seabed mineral resources, the mechanisms of seabed mineral formation, and the environmental impacts of resource extraction. Since 1962, the USGS has also led scientific inquiries into the potential for deep sea mining. By providing impartial science on seabed minerals and their environmental setting in the deep oceans, the USGS enables decision-makers to evaluate the best practices for mineral resource development.

Fact Sheet↗

USGS2004

Baseline Characteristics of Jordan Creek, Juneau, Alaska

Anadromous fish populations historically have found healthy habitat in Jordan Creek, Juneau, Alaska. Concern regarding potential degradation to the habitat by urban development within the Mendenhall Valley led to a cooperative study among the City and Borough of Juneau, Alaska Department of Environmental Conservation, and the U.S. Geological Survey, that assessed current hydrologic, water-quality, and physical-habitat conditions of the stream corridor. Periods of no streamflow were not uncommon at the Jordan Creek below Egan Drive near Auke Bay stream gaging station. Additional flow measurements indicate that periods of no flow are more frequent downstream of the gaging station. Although periods of no flow typically were in March and April, streamflow measurements collected prior to 1999 indicate similar periods in January, suggesting that no flow conditions may occur at any time during the winter months. This dewatering in the lower reaches likely limits fish rearing and spawning habitat as well as limiting the migration of juvenile salmon out to the ocean during some years. Dissolved-oxygen concentrations may not be suitable for fish survival during some winter periods in the Jordan Creek watershed. Dissolved-oxygen concentrations were measured as low as 2.8 mg/L at the gaging station and were measured as low as 0.85 mg/L in a tributary to Jordan Creek. Intermittent measurements of pH and dissolved-oxygen concentrations in the mid-reaches of Jordan Creek were all within acceptable limits for fish survival, however, few measurements of these parameters were made during winter-low-flow conditions. One set of water quality samples was collected at six different sites in the Jordan Creek watershed and analyzed for major ions and dissolved nutrients. Major-ion chemistry showed Jordan Creek is calcium bicarbonate type water with little variation between sampling sites.

Open-File Report↗

USGS2010

Stratiform chromite deposit model

Stratiform chromite deposits are of great economic importance, yet their origin and evolution remain highly debated. Layered igneous intrusions such as the Bushveld, Great Dyke, Kemi, and Stillwater Complexes, provide opportunities for studying magmatic differentiation processes and assimilation within the crust, as well as related ore-deposit formation. Chromite-rich seams within layered intrusions host the majority of the world's chromium reserves and may contain significant platinum-group-element (PGE) mineralization. This model of stratiform chromite deposits is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. The model focuses on features that may be common to all stratiform chromite deposits as a way to gain insight into the processes that gave rise to their emplacement and to the significant economic resources contained in them.

Open-File Report↗

USGS2011

Carbonatite and alkaline intrusion-related rare earth element deposits–A deposit model

The rare earth elements are not as rare in nature as their name implies, but economic deposits with these elements are not common and few deposits have been large producers. In the past 25 years, demand for rare earth elements has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare earth elements come from only a few sources. China produces more than 95 percent of the world's supply of rare earth elements. Because of China's decision to restrict exports of these elements, the price of rare earth elements has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare earth elements deposits, and identifying and quantifying our nation's rare earth elements resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. The general mineral deposit model summarized here is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Carbonatite and alkaline intrusion-related REE deposits are discussed together because of their spatial association, common enrichment in incompatible elements, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare earth elements, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.

Open-File Report↗

USGS1998

Methods for comparing water-quality conditions among National Water-Quality Assessment Study Units, 1992-1995

The National Water-Quality Assessment is based on intensive investigations of stream and ground-water quality in selected major hydrologic basins (study units) of the United States. One objective of the national assessment is to comparatively evaluate water-quality conditions within and among the different study units. Methods were developed to compare the water-quality conditions of 20 study units that were studied during 1992-1995. Two approaches were taken: (1) water-quality conditions for each study unit were ranked in relation to the findings for all study units, and (2) water-quality conditions for each study unit were compared to established criteria for the protection of human health and aquatic life. Separate rankings were developed for several major characteristics of water quality by using selected combinations of measured values for individual constituents or properties. The water-quality characteristics that were evaluated for streams were nutrients and pesticides in water, organochlorine pesticides and polychlorinated biphenyls in bed sediment and tissue, semivolatile organic compounds and trace elements in bed sediment, fish community degradation, and stream habitat degradation. The water-quality characteristics that were evaluated for ground water were nitrate, pesticides, volatile organic compounds, dissolved solids, and radon. The water-quality rankings are relative strictly to the distribution of conditions measured at sampling sites included in developing the method. Sites in the first 20 National Water-Quality Assessment study units include a broad range of environmental settings, but are not a statistically representative sample of the Nation. > To supplement the relative rankings, established water-quality criteria were used to indicate where particular constituents may have adverse effects, and thus merit further investigation. Established water-quality criteria, which provide consistent benchmarks for national comparisons of individual constituents, were selected from a variety of sources and applied to specific constituents in the specific medium (water or sediment) appropriate for each criterion.

Open-File Report↗

USGS2006

Simulation of Water Levels and Salinity in the Rivers and Tidal Marshes in the Vicinity of the Savannah National Wildlife Refuge, Coastal South Carolina and Georgia

The Savannah Harbor is one of the busiest ports on the East Coast of the United States and is located downstream from the Savannah National Wildlife Refuge, which is one of the Nation?s largest freshwater tidal marshes. The Georgia Ports Authority and the U.S. Army Corps of Engineers funded hydrodynamic and ecological studies to evaluate the potential effects of a proposed deepening of Savannah Harbor as part of the Environmental Impact Statement. These studies included a three-dimensional (3D) model of the Savannah River estuary system, which was developed to simulate changes in water levels and salinity in the system in response to geometry changes as a result of the deepening of Savannah Harbor, and a marsh-succession model that predicts plant distribution in the tidal marshes in response to changes in the water-level and salinity conditions in the marsh. Beginning in May 2001, the U.S. Geological Survey entered into cooperative agreements with the Georgia Ports Authority to develop empirical models to simulate the water level and salinity of the rivers and tidal marshes in the vicinity of the Savannah National Wildlife Refuge and to link the 3D hydrodynamic river-estuary model and the marsh-succession model. For the development of these models, many different databases were created that describe the complexity and behaviors of the estuary. The U.S. Geological Survey has maintained a network of continuous streamflow, water-level, and specific-conductance (field measurement to compute salinity) river gages in the study area since the 1980s and a network of water-level and salinity marsh gages in the study area since 1999. The Georgia Ports Authority collected water-level and salinity data during summer 1997 and 1999 and collected continuous water-level and salinity data in the marsh and connecting tidal creeks from 1999 to 2002. Most of the databases comprise time series that differ by variable type, periods of record, measurement frequency, location, and reliability. Understanding freshwater inflows, tidal water levels, and specific conductance in the rivers and marshes is critical to enhancing the predictive capabilities of a successful marsh succession model. Data-mining techniques, including artificial neural network (ANN) models, were applied to address various needs of the ecology study and to integrate the riverine predictions from the 3D model to the marsh-succession model. ANN models were developed to simulate riverine water levels and specific conductance in the vicinity of the tidal marshes for the full range of historical conditions using data from the river gaging networks. ANN models were also developed to simulate the marsh water levels and pore-water salinities using data from the marsh gaging networks. Using the marsh ANN models, the continuous marsh network was hindcasted to be concurrent with the long-term riverine network. The hindcasted data allow ecologists to compute hydrologic parameters?such as hydroperiods and exposure frequency?to help analyze historical vegetation data. To integrate the 3D hydrodynamic model, the marsh-succession model, and various time-series databases, a decision support system (DSS) was developed to support the various needs of regulatory and scientific stakeholders. The DSS required the development of a spreadsheet application that integrates the database, 3D hydrodynamic model output, and ANN riverine and marsh models into a single package that is easy to use and can be readily disseminated. The DSS allows users to evaluate water-level and salinity response for different hydrologic conditions. Savannah River streamflows can be controlled by the user as constant flow, a percentage of historical flows, a percentile daily flow hydrograph, or as a user-specified hydrograph. The DSS can also use output from the 3D model at stream gages near the Savannah National Wildlife Refuge to simulate the effects in the tidal marshes. The DSS is distributed with a two-dimensional (

Georgia, South Carolina↗