User:Benbella/ Surface Water Quality Modeling
EPA/600/3—85/040 June 1985
RATES, CONSTANTS, AND KINETICS FORMULATIONS IN SURFACE WATER QUALITY MODELING (SECOND EDITION)
By
George L. Bowie, William B. Mills, Donald B. Porcella, Carrie L. Campbell, James R. Pagenkopf,
Gretchen L. Rupp, Kay M. Johnson, Peter W.H. Chan, Steven A. Gherini
Tetra Tech, Incorporated
Lafayette, California 94549
and
Charles E. Chamberlin
Humboldt State University
Arcata, California 95521
Contract 68—03—3131
Project Officer
Thomas 0. Barnwell, Jr.
Technology Development and Applications Branch Environmental Research Laboratory
Athens, Georgia 30613
ENVIRONMENTAL RESEARCH LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT U.S. ENVIRONMENTAL PROTECTION AGENCY
ATHENS, GEORGIA 30613
DISCLAIMER
The information in this document has been funded wholly or in part by the United States Environmental Protection Agency under Contract No. 68-03- 3131 to Tetra Tech, Incorporated. It has been subject to the Agency’s peer and administrative review, and it has been approved for publication as an EPA document. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the U.S. Environmental Protection Agency.
FOREWORD
As environmental controls become more costly to implement and the penalties of judgment errors become more severe, environmental quality management requires more efficient analytical tools based on greater knowledge of the environmental phenomena to be managed. As part of this Laboratory’s research on the occurrence, movement, transformation, impact, and control of environmental contaminants, the Technology Development and Applications Branch develops management or engineering tools to help pollution control officials achieve water quality goals.
Basin planning requires a set of analysis procedures that can provide an assessment on the current state of the environment and a means of predicting the effectiveness of alternative pollution control strategies. This report contains a revised and updated compilation and discussion of rates, constants, and kinetics formulations that have been used to accomplish these tasks. It Is directed. toward all water quality planners who must interpret technical information from many sources and recomend the most prudent course of action that will minimize the cost of implementation of a pollutant control activity and maximize the environmental benefits to the comunity.
Rosemarie C. Russo
Director
Environmental Research Laboratory
Athens, Georgia
ABSTRACT
Recent studies are reviewed to provide a comprehensive volume on state— of—the—art formulations used in surface water quality modeling along with accepted values for rate constants and coefficients. Topics covered include: dispersion, heat budgets, dissolved oxygen saturation, reaeration, CBOD decay, NBOO decay, sediment oxygen demand, photosynthesis, pH and alkalinity, nutrients, algae, zooplankton, and coliform bacteria. Factors affecting the specific phenomena and methods of measurement are discussed in addition to data on rate constants.
This report was submitted in fulfillment of Contract No. 68—03—3131 by Tetra Tech, Incorporated, under the sponsorship of the U.S. Environmental Protection Agency. The report covers the period June 1983 to April 1985, and work was completed as of April 1985.
ACKNOWLEDGMENTS
Special thanks are due to the participants in the Rates Manual Workshop held at Tetra Tech, Lafayette during November 29—30, 1984 to review the first draft of the report. These include Ray Whittemore (National Council of the Paper Industry for Air and Stream Improvement, Inc.), Steve McCutcheori (U.S. Geological Survey), Kent Thornton (Ford, Thornton, and Norton, Inc.), Vic Bierman (U.S. Environmental Protection Agency), Tom Barnwell (U.S. Environmental Protection Agency), Don Scavia (National Oceanic and Atmospheric Administration), Tom Gallagher (HydroQual, Inc.), Carl Chen (Systech, Inc.), Jerry Orlob (University of California, Davis), Lam Lau (National Water Research Institute, Ontario, Canada), Bill Walker (private consultant), and Peter Shanahan (Environmental Research and Technology, Inc.). Betsy Southerland (U.S. Environmental Protection Agency) was unable to attend but also participated in the review of the first draft. The above individuals provided many useful comments and references which were incorporated in the final report.
Numerous other individuals also provided reference materials during the preparation of this report. Although they are too numerous to mention here, their input is greatly appreciated.
We would also like to thank Trudy Rokas, Susan Madson, Gloria Sellers, Belinda Ham, and Faye Connaway for typing and preparing the report, and Marilyn Davies for providing most of the graphics.
Finally, thanks are due most to Tom Barnwell and the U.S. Environmental Protection Agency, Environmental Research Laboratory, Athens, Georgiafor both funding the project and providing technical input and guidance.
INTRODUCTION
Background
The use of mathematical models to Simulate ecological and water quality interactions in surface waters has grown dramatically over the past two decades. Simulation techniques offer an integrated and relatively sound course for evaluating wasteload abatement alternatives. Predictions of system behavior based upon mathematical simulation techniques may be misleading, however, particularly if the physical mechanisms involved are not accurately represented in the model. Furthermore, even where the model does faithfully describe mechanisms in the prototype, poor results may be obtained where insufficient data are available to estimate rate constants and coefficients.
Much of the work done in the water quality modeling field has been oriented toward improvement of models——toward incorporating better numerical solution techniques, toward an expanded complement of water quality constituents simulated, and toward realistic representations of modeled physical, chemical, and biological phenomena. There is, however, a need for a document that summarizes the rate constants and coefficients (e.g., nitrification rates and reaeration rates) needed in the models. This document is intended to satisfy that need.
The first edition of this document was published seven years ago (Zison etal., 1978). Because an extensive body of literature on rate constants and modeling formulations has emerged since that time, the United States Environmental Protection Agency has sponsored an updating of the manual. In addition, a workshop was held to evaluate the manual, to review the formulations and associated coefficients and rate values, and to provide further data for the final document. As a result of the literature review and workshop, a substantially new manual has been produced.
Purpose and Use of this Manual
This manual is intended for use by practitioners as a handbook——a convenient reference on modeling formulations, constants, and rates commonly used in surface water quality simulations. Guidance is provided in selecting appropriate formulations or values àf rate constants for specific applications. The manual also provides a range of coefficient values that can be used to perform sensitivity analyses. Where appropriate, measurement techniques for rate constants are also discussed.
It was impossible, however, to encompass all formulations or to examine all recent reports containing rates data. it is hoped, therefore, that the user will recognize the desirability of seeking additional sources where questions remain about formulations or values. Data used from within this volume should be recognized as representing a sampling from a larger set of data. It should also be noted that there are often very real limitations involved in using literature values for rates rather than observed system values. It is hoped that this document will find its main use as a guide in the search for "the correct value" rather than as the sole source of that value.
Scope and Arrangement of Manual
In preparing this manual, an attempt was made to present a comprehensive set of formulations and associated constants. In contrast to the first edition (Zison et al. ,1978) , the manual has been divided into sections containing specific topics. Following this introduction, chapters are presented that discuss the following topics:
- Physical processes of dispersion and temperature
- Dissolved oxygen
- pH and alkalinity
- Nutrients
- Algae
- Zooplankton
- Coliforms
The parameters that are addressed in this manual are those that traditionally have been the focus of water quality management and the focus for control of conventional pollutants. These include temperature, dissolved oxygen, nutrients and eutrophication, and coliform bacteria. Higher organisms (fish, benthos) are not discussed, nor are the details of higher trophic levels in ecosystem models. Also, hydrodynamic processes, although important, are not dealt with in detail.
General Observations on Model Formulations, Rate, Constants, and Coefficients
Each rate value or expression used in a model should not be chosen as an “afterthought”, but should be considered as an integral part of the modeling process. A substantial portion of any modeling effort should go into selecting specific approaches and formulations based upon the objectives of modeling, the kinds and amounts of data available, and the strengths and weaknesses of the approach or formulation. Once formulations have been selected, a significant effort should be made to determine satisfactory valuers for parameters. Even where the parameter is to be chosen by calibration, it is clearly important to establish whether the calibrated value is within a reasonable range or not. Recent references: on model calibration include Thomann (1983) National Council on Air and Stream Improvement (1982), and Beck (1983). Users should be aware that an acceptable model calibration does not imply that the model has predictive capability. The model may contain incorrect mechanisms, and agreement between model predictions and observations could have been obtained through an unrealistic choice of parameter values. Further, the future status of the prototype may be controlled by processes not even simulated in the model.
Values of many constants and coefficients are dependent upon the way they are used in modeling formulations. For example, while pollutant dispersion is an observable physical process, modeling this process is partly a mathematical construct. Therefore, constants that are used to represent the process (i.e., dispersion coefficients) cannot be chosen purely on the basis of physics since they also depend on the modeling approach. For example, to determine the dispersion coefficients in a model application to an estuary, both the time and length scales of the model must be considered. Whether the model is tidally averaged or simulates intra—tidal variations, and whether the model is 1—, 2—, or 3— dimensional, all influence the value of the appropriate dispersion coefficient for that model. Ford and Thornton (1979) discuss scale effects in ecological models, and conclude that inconsistent scales for the hydrodynamics, chemistry, and biology may produce erroneous model predictions. Since coefficient values are never known with certainty, modelers are constantly faced with the question of how accurately rate constants should be known. The relationship between uncertainty in coefficient values and model predictions can be evaluated by performing sensitivity analyses. For models with few parameters, sensitivity analyses are generally straightforward. However, for complex models, sensitivity analyses are no longer straightforward since many dynamic interactions are involved. Sensitivity analyses are discussed in detail in Thornton and Lessem (1976), Thornton (1983), and Beck (1983).
References
Beck, M.B. 1983. Sensitivity Analysis, Calibration, and Validation. In: Mathematical Modeling of Water Quality: Streams, Lakes, and Reservoirs. The International Institute for Applied Systems Analysis. Editor: G.T. Orlob.
Ford, D.E. and K.S. Thornton. 1979. Time and Length Scales for the One— Dimensional Assumption and its Relation to Ecological Models. Water Resources Research. Vol. 15, No. 1, pp. 113—120.
National Council of the Paper Industry for Air and Stream Improvement, Inc. 1982., A Study of the Selection, Calibration and Verification of Mathematical Water Quality Models. NCASI Tech. Bull. 367, New York.
Thomann, R.V. 1982. Verification of Water Quality Models. Journal of Environmental Engineering Division, ASCE. Vol. 108, No. EE5, October, pp. 923—940.
Thornton, K.W. and A.S. Lessem. 1976. Sensitivity Analysis of the Water Quality for River—Reservoir Systems Model. U.S. Army Waterways Experiment Station. Misc. Paper Y—76—4.
Thornton, K.W. 1983. Sensitivity Analysis in Simulation Experimentation. Encyclopedia of Systems and Control. Pergamon Press.
Zison, S.W., W.B. Mills, D. Deimer, and C.W. Chen. 1978. Rates Constants and Kinetics Formulations in Surface Water Quality Modeling. Prepared by Tetra Tech. Inc., Lafayette, CA, for Environmental Research Laboratory, USEPA, Athens, GA. EPA—600/3—78—105. 335 pp.
PHYSICAL PROCESSES
Introduction
The purpose of this chapter is to give the reader an overview of how the major physical processes are incorporated into water quality and ecosystem simulations. Since a detailed review is beyond the scope of this report, the reader is encouraged to review the articles listed in Table 2-1 which represent several of the more complete and recent reviews of the state-of-the-art in physical process modeling.
Physical processes often simulated in water quality models include flow and circulation patterns, mixing and dispersion, water temperature, and the density distribution (which is a function of temperature, salinity, and suspended solids concentrations) over the water column. It is stressed that quality predictions are very dependent upon the physical processes and how well these are represented in the water quality simulations. Despite this dependence, the modeler often is forced to make a trade-off between acceptable degree of detail in water quality vs. physical process simulation due to cost or other restrictions. It is desirable from the standpoint of both the engineer and ecosystem analyst, therefore, to select the simplest model which satisfies the temporal and spatial resolution required for water quality and/or ecosystem simulation. For example, the optimum time step for dynamic simulation of a fully-mixed impoundment would be 3-6 hours for capturing diurnal fluctuations, and daily or weekly for strongly stratified impoundments which normally exhibit slowly varying conditions. In terms of spatial resolution. required, the analyst should take advantage of the possible simplifications of dominate physical characteristics (i.e., physical shape, stratified layers, mixing zones, etc.). [more]
TABLE 2-1. MAJOR REVIEWS OF MODELING STATE-OF-THE-ART
French, R.H. 1983. Lake Modeling: State-of-the-Art. In: CRC Critical Reviews in Environmental Control, Vol. 13, Issue 4, pgs. 311-357.
Harleman, D.R.F. 1982. Hydrothermal Analysis of Lakes and Reservoirs. Journal of the Hydraulics Division, ASCE. Vol. 108, No. HY3, pp. 302-325.
Johnson, B. 1982. A Review of Multi-Dimensional Numerical Modeling of Reservoir Hydrodynamics. U.S. Army Corps of Engineers, Waterways Experiment Station.
Fischer, H.B., List, E.J., Koh, R.C.Y. Imberger, J., and Brooks, N.H. 1979. Mixing in Inland and Coastal Waters. Academic Press, New York.
Hinwood, J.B., and Wallis, I.G. 1975. Review of Models of Tidal Waters. Journal of the Hydraulics Division, ASCE, Vol. 101, No. HY11, Proc. Paper 11693, November, 1975.
Orlob, G.T., ed. 1984. Mathematical Modeling of Water Quality: Streams, Lakes, and Reservoirs. John Wiley and Sons, Wiley-Interscience, N.Y., N.Y.
Elhadi, N., A. Harrington, I. Hill, Y.L. Lau, B.G. Krishnappan. 1984. River Mixing: A State-of-the-Art Report. Canadian Journal of Civil Engineering. Vol. 11, No. 11, pp. 585—609.