Abstract |
The Columbia River from the Pacific Ocean to Bonneville Dam is treated as a series of two-dimensional finite elements in the formulation of a mathematical model of the system. Currents and stages are simulated along the river via an explicit solution of the one-dimensional equations of motion and continuity; two-dimensional conditions in the horizontal are approached by means of a branched network of connecting channels and junctions. Computed net velocities and stages are used as input to the advection-diffusion equation and solutions are obtained for any coupled (e.g., BOD-DO) or uncoupled, first order reaction, conservative and/or non-conservative substance. Emphasis is placed on obtaining a solution for temperature as the dependent variable. Allowance is made for input of meteorological variables and a stepwise heat budget computation is made in order to predict temperature conditions on an hourly basis. A discussion of some existing pollution models, numerical methods and error sources is given; computer programs and program notes are listed. (Author) |