Journal articleWater research · June 2009
Water resource management decisions often depend on mechanistic or empirical models to predict water quality conditions under future pollutant loading scenarios. These decisions, such as whether or not to restrict public access to a water resource area, ma ...
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Journal articleJournal of the American Water Resources Association · December 1, 2007
The National Research Council recommended Adaptive Total Maximum Daily Load implementation with the recognition that the predictive uncertainty of water quality models can be high. Quantifying predictive uncertainty provides important information for model ...
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Journal articleEcological Modelling · November 10, 2007
We examined the spatiotemporal phytoplankton community patterns and identified the nature of the underlying causal mechanisms in a freshwater-saltwater continuum, the Neuse River Estuary (North Carolina, USA). We used a Bayesian structural equation modelin ...
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Journal articleEcological Modelling · November 10, 2007
We introduce the Bayesian calibration of process-based models to address the urgent need for robust modeling tools that can effectively support environmental management. The proposed framework aims to combine the advantageous features of both mechanistic a ...
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Journal articleEnvironmental science & technology · July 2007
A Bayesian approach is used to update and improve water quality model predictions with monitoring data. The objective of this work is to facilitate adaptive management by providing a framework for sequentially updating the assessment of water quality statu ...
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Journal articleEstuarine Coastal and Shelf Science · March 1, 2007
We introduce a Bayesian structural equation modeling framework to explore the spatiotemporal phytoplankton community patterns in the Neuse River Estuary (study period 1995-2001). The initial hypothesized model considered the influence of the physical envir ...
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Journal articleThe Science of the total environment · March 2007
Uncertainty is an inevitable source of noise in water quality management and will weaken the adequacy of decisions. Uncertainty is derived from imperfect information, natural variability, and knowledge-based inconsistency. To make better decisions, it is n ...
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Journal articleEnvironmental science & technology · November 2006
We examined the factors that determine the citations of 153 mechanistic aquatic biogeochemical modeling papers published from 1990 to 2002. Our analysis provides overwhelming evidence that ocean modeling is a dynamic area of the current modeling practice. ...
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Journal articleEcology · June 2006
Ecological data analysis often involves fitting linear or nonlinear equations to data after transforming either the response variable, the right side of the equation, or both, so that the standard suite of regression assumptions are more closely met. Howev ...
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Journal articleWater Resources Research · March 1, 2006
The hydrologic sciences must play a major role in improving our understanding of the transport and fate of the vast amount of reactive nitrogen that is being added to the environment by human activities. Detailed understanding of the function of different ...
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Journal articleEcological Modelling · February 25, 2006
Structural equation modeling is a multivariate statistical method that allows evaluation of a network of relationships between manifest and latent variables. In this statistical technique, preconceptualizations that reflect research questions or existing k ...
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Journal articleWater Resources Research · July 1, 2005
A Bayesian nonlinear regression modeling method is introduced and compared with the least squares method for modeling nutrient loads in stream networks. The objective of the study is to better model spatial correlation in river basin hydrology and land use ...
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Journal articleEnvironmental science & technology · May 2005
Violation of a water quality standard triggers the need for a total maximum daily load (TMDL); this should result in actions that improve water quality, but sometimes at significant cost. If the standard is well-conceived, a designated-use statement charac ...
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Journal articleJournal of Environmental Engineering · June 1, 2004
The total maximum daily load (TMDL) concept provides the basis for regulating pollution load from riverine sources to impaired water bodies. However, load is comprised of two components: flow and concentration. These two components may have confounding, or ...
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Journal articleEcological Modelling · April 1, 2004
A Bayesian network consists of a graphical structure and a probabilistic description of the relationships among variables in a system. The graphical structure explicitly represents cause-and-effect assumptions that allow a complex causal chain linking acti ...
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Journal articleJournal of Water Resources Planning and Management · July 1, 2003
We develop a probability network model to characterize eutrophication in the Neuse River Estuary, North Carolina, and support the estimation of a total maximum daily load (TMDL) for nitrogen. Unlike conventional simulation models, probability networks desc ...
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Journal articleJournal of Water Resources Planning and Management · July 1, 2003
The North Carolina Division of Water Quality developed a total maximum daily load (TMDL) to reduce nitrogen inputs into the Neuse River Estuary to address the problem of repeated violations of the ambient chlorophyll a criterion. Three distinct water quali ...
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Journal articleEnvironmental science & technology · May 2002
To address the impaired condition of the water bodies listed under Section 303(d) of the Clean Water Act, over 40 000 total maximum daily loads (TMDLs) for pollutants must be developed during the next 10-15 years. Most of these will be based on the results ...
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Journal articleGroup Decision and Negotiation · December 1, 2001
In 1998, the North Carolina Legislature mandated a 30% reduction in the nitrogen loading in the Neuse River in an attempt to reduce undesirable environmental conditions in the lower river and estuary. Although sophisticated scientific models of the Neuse e ...
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Journal articleEcological Modelling · September 15, 2001
Ecological models that have a theoretical basis and yet are mathematically simple enough to be parameterized using available data are likely to be the most useful for environmental management and decision-making. Mechanistic foundations improve confidence ...
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Journal articleJAWRA Journal of the American Water Resources Association · December 2000
ABSTRACT: A survey of numerous field studies shows that nitrogen and phosphorous export coefficients are significantly different across forest, agriculture, and urban land‐cover types. We used simulations to estimate the lan ...
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Journal articleEnvironmental pollution (Barking, Essex : 1987) · January 1999
Models addressing excessive nutrient loading in the environment originated over 50 years ago with the simple nutrient concentration thresholds proposed by Sawyer (1947. Fertilization of lakes by agricultural and urban drainage. New Engl. Water Works Assoc. ...
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Journal articleCanadian Journal of Fisheries and Aquatic Sciences · January 1, 1999
It is a common strategy in surface water quality modeling to attempt to remedy predictive inadequacies by incorporating additional mechanistic detail into the model. This approach reflects the reasonable belief that enhanced scientific understanding of bas ...
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Journal articleHuman and Ecological Risk Assessment Hera · January 1, 1999
Risk assessment and uncertainty analysis are important tools for improving environmental decision making. However, their value is limited when the environmental endpoints assessed by scientists do not coincide with the publicly-meaningful attributes that a ...
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Journal articleEnvironmental Monitoring and Assessment · January 1, 1999
The United States funds a number of national monitoring programs to measure the status and trends of ecological and natural resources. Each of these programs has a unique focus; the scientific objectives are different as are the sample designs. However, in ...
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Journal articleWater Resources Research · January 1, 1998
Phosphorus-enriched agricultural runoff from the Everglades Agriculture Area is believed to have caused ecological changes in the northern part of the Everglades wetlands. A number of efforts have been made to assess the effectiveness of using constructed ...
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Journal articleEcological Modelling · April 15, 1997
As a first step in a Bayesian analysis of PCB fate and transport in the upper Hudson River, a joint probability density function for parameters in a simulation model is created. The density function describes the joint probabilities of the following parame ...
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Journal articleGround Water · January 1, 1997
Cost-effective monitoring strategies exist for estimating mean depth to the water table and for characterizing fluctuations about that mean. These strategies can also be used to evaluate the utility of sparse water level data sets for making such estimates ...
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Journal articleJournal of Environmental Engineering ASCE · May 1, 1996
Modelers of contaminant fate and transport in surface waters typically rely on literature values when selecting parameter values for mechanistic models. While the expert judgment with which these selections are made is valuable, the information contained i ...
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Journal articleWater Resources Research · January 1, 1996
We investigated observation-error-induced parameter bias using least squares and Stein-corrected least squares estimators in a model for predicting lake phosphorus. The Stein-corrected estimator performed better than the uncorrected estimator from bias and ...
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Journal articleWater Resources Bulletin · January 1, 1996
The US Environmental Protection Agency is currently developing guidance for assessing environmental impact using biocriteria within a regulatory framework. Of particular interest are statistical methods of design and analysis to test for impairment of biol ...
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Journal articleEnvironmental Management · March 1, 1994
Uncertainty in environmental decision making should not be thought of as a problem that is best ignored. In fact, as is illustrated in a simple example, we often informally make use of awareness of uncertainty by hedging decisions away from large losses. T ...
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Journal articleWater Resources Research · January 1, 1994
In the past several years, wetlands have become increasingly used for wastewater treatment purposes. As a consequence, nutrient trapping and accumulation, particularly for phosphorus, have emerged as important environmental management issues. To predict th ...
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Journal articleEnvironmental Toxicology and Chemistry · January 1, 1994
A decision analytic approach is proposed for environmental planning and analysis under scientific uncertainty. This approach begins with the creation of a planning framework that consists of all relevant objectives and attributes, along with all feasible m ...
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Journal articleEcological Modelling · January 1, 1994
The usefulness of water quality simulation models for environmental management is explored with a focus on prediction uncertainty. Ecological risk and environmental analysis often involve scientific assessments that are highly uncertain. Still, environment ...
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Journal articleEcological Modelling · January 1, 1993
Statistical models of nutrient-phytoplankton relationships in lakes are usually fitted on cross-sectional data sets and thus describe multi-lake behavior using a single set of global model parameters. As a result, prediction of individual lake response ref ...
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Journal articleEcology · January 1, 1990
Classical hypothesis testing is founded on a long-run frequency perspective that is the basis for error rates and P values used in classical statistical inference. Thus in ecological studies involving formal hypothesis testing, it is common practice to rep ...
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Journal articleJournal of Environmental Engineering United States · January 1, 1990
Current practice for the verification of water-quality simulation models is to use a combination of modeler judgment and graphical analysis to assess the adequacy of a model. Statistical testing of goodness-of-fit is sometimes undertaken, but usually with ...
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Journal articleWater Resources Research · January 1, 1988
Empirical models of fish response to lake acidification were recently fit to a large historical data set from the Adirondack region of the United States using classical and Bayesian methods. The models may be used to predict species presence/absence for br ...
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Journal articleCanadian Journal of Fisheries and Aquatic Sciences · January 1, 1987
A large historical data set from the Adirondack region of New York was compiled to study the relationship between water chemistry variables associated with acid precipitation and the presence/absence of selected fish species. The data set was used to exami ...
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Journal articleJawra Journal of the American Water Resources Association · January 1, 1985
Models for pollutant runoff can be useful in water quality management planning if appropriately structured for the problem at hand. Accordingly, a “top‐down” approach is proposed for the examination of extant pollutant runoff models. The approach consists ...
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Journal articleWater Research · January 1, 1983
Recent work on methods of error analysis to accompany the application of lake models has not enjoyed great acceptance in part because of the magnitude of the error term. For the models that have undergone a rigorous error analysis (generally the single equ ...
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Journal articleEcological Modelling · January 1, 1983
Water quality simulation models, whether descriptive or predictive, must undergo confirmatory analyses if inferences drawn from the models are to be meaningful. Current practices in the confirmation of simulation models are examined and criticized from thi ...
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Journal articleCanadian Journal of Fisheries and Aquatic Sciences · September 1, 1980
Recent work in the area of empirical lake modeling and error analysis has resulted in some useful methods for the assessment of lake trophic quality. These methods are incorporated into the procedure presented herein for the prediction of lake pho ...
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Journal articleCanadian Journal of Fisheries and Aquatic Sciences · February 1, 1980
Water quality sampling and data analysis are undertaken to acquire and convey information. Therefore, when data are presented, the form of this presentation should be such that information transfer is high. For example, a graph or table of average ...
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Journal articleWater Resources Research · December 1979
A statistical technique proposed for the estimation of the uncertainty in the prediction of phosphorus concentration in lakes using the Dillon‐Rigler‐Kirchner model can increase the practical value of this and similar models. The usefulness of this ...
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Journal articleJournal of the Fisheries Research Board of Canada · February 1, 1979
Data from North Temperate lakes were used to estimate the uncertainty of a phosphorus loading model. A number of graphical representations of the uncertainty were developed to demonstrate the importance of including probabilistic information in ph ...
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