Download or read book Parameter Estimation and Uncertainty Analysis of Contaminant First Arrival Times at Household Drinking Water Wells written by Mary Kang and published by . This book was released on 2007 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exposure assessment, which is an investigation of the extent of human exposure to a specific contaminant, must include estimates of the duration and frequency of exposure. For a groundwater system, the duration of exposure is controlled largely by the arrival time of the contaminant of concern at a drinking water well. This arrival time, which is normally estimated by using groundwater flow and transport models, can have a range of possible values due to the uncertainties that are typically present in real problems. Earlier arrival times generally represent low likelihood events, but play a crucial role in the decision-making process that must be conservative and precautionary, especially when evaluating the potential for adverse health impacts. Therefore, an emphasis must be placed on the accuracy of the leading tail region in the likelihood distribution of possible arrival times. To demonstrate an approach to quantify the uncertainty of arrival times, a real contaminant transport problem which involves TCE contamination due to releases from the Lockformer Company Facility in Lisle, Illinois is used. The approach used in this research consists of two major components: inverse modelling or parameter estimation, and uncertainty analysis. The parameter estimation process for this case study was selected based on insufficiencies in the model and observational data due to errors, biases, and limitations. A consideration of its purpose, which is to aid in characterising uncertainty, was also made in the process by including many possible variations in attempts to minimize assumptions. A preliminary investigation was conducted using a well-accepted parameter estimation method, PEST, and the corresponding findings were used to define characteristics of the parameter estimation process applied to this case study. Numerous objective functions, which include the well-known L2-estimator, robust estimators (L1-estimators and M-estimators), penalty functions, and deadzones, were incorporated in the parameter estimation process to treat specific insufficiencies. The concept of equifinality was adopted and multiple maximum likelihood parameter sets were accepted if pre-defined physical criteria were met. For each objective function, three procedures were implemented as a part of the parameter estimation approach for the given case study: a multistart procedure, a stochastic search using the Dynamically-Dimensioned Search (DDS), and a test for acceptance based on predefined physical criteria. The best performance in terms of the ability of parameter sets to satisfy the physical criteria was achieved using a Cauchy's M-estimator that was modified for this study and designated as the LRS1 M-estimator. Due to uncertainties, multiple parameter sets obtained with the LRS1 M-estimator, the L1-estimator, and the L2-estimator are recommended for use in uncertainty analysis. Penalty functions had to be incorporated into the objective function definitions to generate a sufficient number of acceptable parameter sets; in contrast, deadzones proved to produce negligible benefits. The characteristics for parameter sets were examined in terms of frequency histograms and plots of parameter value versus objective function value to infer the nature of the likelihood distributions of parameters. The correlation structure was estimated using Pearson's product-moment correlation coefficient. The parameters are generally distributed uniformly or appear to follow a random nature with few correlations in the parameter space that results after the implementation of the multistart procedure. The execution of the search procedure results in the introduction of many correlations and in parameter distributions that appear to follow lognormal, normal, or uniform distributions. The application of the physical criteria refines the parameter characteristics in the parameter space resulting from the search procedure by reducing anomalies. The combined effect of optimization and the application of the physical criteria performs the function of behavioural thresholds by removing parameter sets with high objective function values. Uncertainty analysis is performed with parameter sets obtained through two different sampling methodologies: the Monte Carlo sampling methodology, which randomly and independently samples from user-defined distributions, and the physically-based DDS-AU (P-DDS-AU) sampling methodology, which is developed based on the multiple parameter sets acquired during the parameter estimation process. Monte Carlo samples are found to be inadequate for uncertainty analysis of this case study due to its inability to find parameter sets that meet the predefined physical criteria. Successful results are achieved using the P-DDS-AU sampling methodology that inherently accounts for parameter correlations and does not require assumptions regarding parameter distributions. For the P-DDS-AU samples, uncertainty representation is performed using four definitions based on pseudo-likelihoods: two based on the Nash and Sutcliffe efficiency criterion, and two based on inverse error or residual variance. The definitions consist of shaping factors that strongly affect the resulting likelihood distribution. In addition, some definitions are affected by the objective function definition. Therefore, all variations are considered in the development of likelihood distribution envelopes, which are designed to maximize the amount of information available to decision-makers. The considerations that are important to the creation of an uncertainty envelope are outlined in this thesis. In general, greater uncertainty appears to be present at the tails of the distribution. For a refinement of the uncertainty envelopes, the application of additional physical criteria is recommended. The selection of likelihood and objective function definitions and their properties are made based on the needs of the problem; therefore, preliminary investigations should always be conducted to provide a basis for selecting appropriate methods and definitions. It is imperative to remember that the communication of assumptions and definitions used in both parameter estimation and uncertainty analysis is crucial in decision-making scenarios.
Download or read book Master s Theses Directories written by and published by . This book was released on 2007 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Education, arts and social sciences, natural and technical sciences in the United States and Canada".
Download or read book Parameter Estimation and Uncertainty Quantification in Water Resources Modeling written by Philippe Renard and published by Frontiers Media SA. This book was released on 2020-04-22 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical models of flow and transport processes are heavily employed in the fields of surface, soil, and groundwater hydrology. They are used to interpret field observations, analyze complex and coupled processes, or to support decision making related to large societal issues such as the water-energy nexus or sustainable water management and food production. Parameter estimation and uncertainty quantification are two key features of modern science-based predictions. When applied to water resources, these tasks must cope with many degrees of freedom and large datasets. Both are challenging and require novel theoretical and computational approaches to handle complex models with large number of unknown parameters.
Download or read book Sensitivity and Uncertainty Analyses of Contaminant Fate and Transport in a Field scale Subsurface System written by Jinjun Wang and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Health scientists often rely on simulation models to reconstruct groundwater contaminant exposure data for retrospective epidemiologic studies. Due to the nature of historical reconstruction process, there are inevitably uncertainties associated with the input data and, therefore, with the final results of the simulation models, potentially adversely impacting related epidemiologic investigations. This study examines the uncertainties associated with the historically reconstructed contaminant fate and transport simulations for an epidemiologic study conducted at U.S. Marine Corps Base Camp Lejeune, North Carolina. To achieve an efficient uncertainty analysis, sensitivity analysis was first conducted to identify the critical uncertain variables, which were then adopted in the uncertainty analysis using an improved Monte Carlo simulation (MCS) method. Particularly, uncertainties associated with the historical contaminant arrival time were evaluated. To quantify the uncertainties in an efficient manner, a procedure identified as Pumping Schedule Optimization System (PSOpS) was developed to obtain the extreme (i.e., earliest and latest) contaminant arrival times caused by pumping schedule variations. Two improved nonlinear programming methodsRank-and-Assign (RAA) and Improved Gradient (IG)are used in PSOpS to provide computational efficiency. Furthermore, a quantitative procedure named Pareto Dominance based Critical Realization Identification (PDCRI) was developed to screen out critical realizations for contaminant transport in subsurface system, so that the extreme contaminant arrival times under multi-parameter uncertainties could be evaluated efficiently.
Download or read book Poisoned Patriots written by United States. Congress. House. Committee on Energy and Commerce. Subcommittee on Oversight and Investigations and published by . This book was released on 2008 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Contaminated Water Supplies at Camp Lejeune written by National Research Council and published by National Academies Press. This book was released on 2009-09-06 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the early 1980s, two water-supply systems on the Marine Corps Base Camp Lejeune in North Carolina were found to be contaminated with the industrial solvents trichloroethylene (TCE) and perchloroethylene (PCE). The water systems were supplied by the Tarawa Terrace and Hadnot Point watertreatment plants, which served enlisted-family housing, barracks for unmarried service personnel, base administrative offices, schools, and recreational areas. The Hadnot Point water system also served the base hospital and an industrial area and supplied water to housing on the Holcomb Boulevard water system (full-time until 1972 and periodically thereafter). This book examines what is known about the contamination of the water supplies at Camp Lejeune and whether the contamination can be linked to any adverse health outcomes in former residents and workers at the base.
Download or read book Guidelines for Drinking water Quality written by World Health Organization and published by World Health Organization. This book was released on 1993 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume describes the methods used in the surveillance of drinking water quality in the light of the special problems of small-community supplies, particularly in developing countries, and outlines the strategies necessary to ensure that surveillance is effective.
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1991 with total page 806 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Standard Methods for the Examination of Water and Wastewater written by American Public Health Association and published by . This book was released on 1981 with total page 1254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Water Availability and Use Science Program Estimated Use of Water in the United States In 2015 written by Cheryl A. Dieter and published by Geological Survey. This book was released on 2018-08-16 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estimates of water withdrawals enable the depiction of trends in total water use for the Nation among different geographic areas, categories of use, and sources over time. Water-use information is a critical component of water budgets, which are essential to surface- water and groundwater availability studies. This information is also essential to accurately understand how future water demands will be met while maintaining adequate water quality and quantities for human and ecosystem needs across the United States of America. Data is represented in text abstracts and analysis, tables, chart graphics, and photos presented throughout. The estimates contained within this volume focus on water use for eight (8) categories: Public Supply * Irrigation Self-supplied Domestic * Livestock Aquaculture * Industrial Mining * Thermoelectric Power Related products: Other products produced by the U.S. Geological Survey (USGS) are available here: https://bookstore.gpo.gov/agency/us-geological-survey-usgs Check out our Water Management resources collection here: https://bookstore.gpo.gov/catalog/water-management
Download or read book Poisoned Patriots Contaminated Drinking Water at Camp Lejeune written by Bart Stupak and published by DIANE Publishing. This book was released on 2008-08 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: Witnesses: Jeff Byron; Mike Gros; Jerome Ensminger; Robert Dickerson, Jr., Command. Gen., Camp Lejeune, NC; Kelly Dreyer, Environ. Restoration Program Mgr., U.S. Marine Corps; Pat Leonard, Office of the Judge Advocate Gen., Claims, Invest., and Tort Litigation; Thomas Sinks, deputy dir., Nat. Center of Environmental Health, Agency for Toxic Substances and Disease Registry (ATSDR), accomp. by Frank Bove, Sr. epidemiologist, ATSDR, and Morris Maslia, environmental engineer, ATSDR; Peter Murtha, Dir., Office of Criminal Enforcement, Forensics and Training, Office of Enforcement and Compliance Assurance, EPA; Marcia Crosse, Dir., Public Health and Military Health Care Issues, GAO; Franklin Hill, Superfund Div., EPA. Illustrations.
Download or read book Bulletin of the Atomic Scientists written by and published by . This book was released on 1970-06 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Bulletin of the Atomic Scientists is the premier public resource on scientific and technological developments that impact global security. Founded by Manhattan Project Scientists, the Bulletin's iconic "Doomsday Clock" stimulates solutions for a safer world.
Download or read book Statistical Methods in Water Resources written by D.R. Helsel and published by Elsevier. This book was released on 1993-03-03 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data on water quality and other environmental issues are being collected at an ever-increasing rate. In the past, however, the techniques used by scientists to interpret this data have not progressed as quickly. This is a book of modern statistical methods for analysis of practical problems in water quality and water resources. The last fifteen years have seen major advances in the fields of exploratory data analysis (EDA) and robust statistical methods. The 'real-life' characteristics of environmental data tend to drive analysis towards the use of these methods. These advances are presented in a practical and relevant format. Alternate methods are compared, highlighting the strengths and weaknesses of each as applied to environmental data. Techniques for trend analysis and dealing with water below the detection limit are topics covered, which are of great interest to consultants in water-quality and hydrology, scientists in state, provincial and federal water resources, and geological survey agencies. The practising water resources scientist will find the worked examples using actual field data from case studies of environmental problems, of real value. Exercises at the end of each chapter enable the mechanics of the methodological process to be fully understood, with data sets included on diskette for easy use. The result is a book that is both up-to-date and immediately relevant to ongoing work in the environmental and water sciences.
Download or read book The cost of inaction written by Gretta Goldenman and published by Nordic Council of Ministers. This book was released on 2019-03-17 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: PFAS (per and polyfluoroalkylsubstances) are known to be extremely difficult to degrade in the environment and to be bioaccumulative and toxic. Exposure to PFAS is suspected to increase the risk of adverse health effects, such as impacts on the thyroid gland, the liver, fat metabolism and the immune system. This study estimates the socioeconomic costs that may result from impacts on human health and the environment from the use of PFAS. Better awareness of the costs and problems associated with PFAS exposure will assist decision-makers and the general public to make more efficient and timely risk management decisions. Findings indicate that the costs are substantial, with annual health-related costs estimated to 2.8 – 4.6 billion EUR for the Nordic countries and 52 – 84 billion EUR for all EEA countries. Overall non-health costs are estimated at 46 million – 11 billion EUR for the Nordic countries.Upon request the excel spreadsheets used for the monetarisation and valuation in this report can also be provided along with a guidance on how to use the estimation of costs for value transfer. Please contact any of the consultants or members of the steering group from the Swedish Chemicals Agency or the Danish Environmental Protection Agency if you are interested in receiving these excel spreadsheets.
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1991 with total page 806 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural Attenuation for Groundwater Remediation written by Commission on Geosciences, Environment, and Resources and published by National Academies Press. This book was released on 2000-08-31 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past decade, officials responsible for clean-up of contaminated groundwater have increasingly turned to natural attenuation-essentially allowing naturally occurring processes to reduce the toxic potential of contaminants-versus engineered solutions. This saves both money and headaches. To the people in surrounding communities, though, it can appear that clean-up officials are simply walking away from contaminated sites. When is natural attenuation the appropriate approach to a clean-up? This book presents the consensus of a diverse committee, informed by the views of researchers, regulators, and community activists. The committee reviews the likely effectiveness of natural attenuation with different classes of contaminants-and describes how to evaluate the "footprints" of natural attenuation at a site to determine whether natural processes will provide adequate clean-up. Included are recommendations for regulatory change. The committee emphasizes the importance of the public's belief and attitudes toward remediation and provides guidance on involving community stakeholders throughout the clean-up process. The book explores how contamination occurs, explaining concepts and terms, and includes case studies from the Hanford nuclear site, military bases, as well as other sites. It provides historical background and important data on clean-up processes and goes on to offer critical reviews of 14 published protocols for evaluating natural attenuation.
