10.2190/BUG1-BWC2-BA5Q-3RKY BUG1BWC2BA5Q3RKY 5 Modeling River Water Quality by the Superposition Method 359 374 20020509 20020509 20020509 20020509 BUG1BWC2BA5Q3RKY.pdf http://baywood.metapress.com/link.asp?target=contribution&id=BUG1BWC2BA5Q3RKY 4 F. X. Yu D. D. Adrian V. P. Singh Louisiana State University, Baton Rouge A one-dimensional (1-D) advection-dispersion equation (ADE) with a first-order biochemical reaction was solved using the superposition method. Three sets of initial and boundary conditions were considered. The boundary condition of the model virtually can be any type of chemical or BOD concentration functions. Thus, the model accepts discrete and time-dependent input and produces a continuous concentration distribution over time and space. A simple and accurate equation was derived to calculate the upper-bound memory time of a given river. Since the model requires only a finite record-length, it can be easily updated. The model was compared with some analytical and numerical models and was found to be accurate, simple, and easy to apply. A. D. Koussis, P. Kokitkar, and A. Mehta, Modeling DO Concentrations in Streams with Dispersion, <i>Journal of Environmental Engineering, ASCE, 116</i>:3, pp. 601-614, 1990. G. B. McBride and J. C. Rutherford, Accurate Modeling of River Pollutant Transport, <i>Journal of Environmental Engineering, ASCE, 110</i>:4, pp. 809-827, 1984. J. Siemons, <i>Numerical Methods for the Solution of Diffusion-Advection Equations</i>, Report 88, Delft Hydr. Lab., Delft, The Netherlands, 1970. H. S. Carslaw and J. C. Jaeger, <i>Conduction of Heat in Solids</i>, Oxford University Press, London, England. W. H. Li, Unsteady Dissolved-Oxygen Sag in a Stream, <i>Journal of the Sanitary Engineering, ASCE, 88</i>:SA3, pp. 75-85, 1962. W. H. Li, Effects of Dispersion on DO-SAG in Uniform Flow, <i>Journal of the Sanitary Engineering, ASCE, 98</i>:SA1, pp. 169-182, 1972. R. V. Thomann, <i>Systems Analysis and Water Quality Management</i>, McGraw-Hill Book Co., New York, p. 140, 1974. M. Th. Van Genuchten, and W. J. Alves, <i>Analytical Solutions of the One-Dimensional Convective-Dispersive Solute Transport Equation</i>, U. S. Department of Agriculture, Agriculture Research Service, Technical Bulletin Number 1661. R. V. Thomann and J. A. Mueller, <i>Principles of Surface Water Quality Modeling and Control</i>, Harper and Row Publishers, New York, 1987. G. K. Y. Luk, L. Lau, and W. E. Watt, Two-Dimensional Mixing in Rivers with Unsteady Pollutant Source, <i>Journal of Environmental Engineering, 116</i>:1, pp. 125-143, 1990. M. J. D. Powell, An Efficient Method for Finding the Minimum of a Function of Several Variables without Calculating Derivatives, <i>Computer Journal, 7</i>, pp. 155-162, 1964. R. Dresnack and W. E. Dobbins, Numerical Analysis of BOD and DO Profiles, <i>Journal of Sanitary Engineering Division, ASCE, 94</i>:SA5, pp. 789-807, 1968.