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For advectiondominated transport processes, the traditional numerical techniques for solving the advectiondiffusion equation fail because of numerical oscillations. Fractional step solutions, in which the advection and diffusion processes are treated in separate steps, have been proposed as one way of overcoming this problem. Here a solution to the advection step based on the method of characteristics on a fixed grid is used. Interpolation is achieved with the finite element technique. Linear and quadratic elements are evaluated in terms of artificial diffusion, phase, and other errors. It was found that linear interpolation creates too much numerical diffusion, while the quadratic scheme is reasonably accurate, but under certain conditions generates spurious extrema. A method retaining the accuracy of the quadratic interpolation and eliminating its shortcoming is suggested. Boundary conditions and source loadings are considered in detail. An application of the model to salinity distribution resulting from canal discharges in Biscayne Bay is described.

The essentials of hydrodynamic model application techniques and necessary supporting data are given for the situation of a partially stratified water body. The presentation is aimed at improving numerical predictions of tidal hydrodynamics, and is oriented toward somewhat experienced modelers. So as to guide the modeler, the subjects covered are arranged in the order in which they ideally would be addressed during the execution of a study. These subjects fall broadly under the headings hydrodynamic classification, model selection, model adaptation, model testing and calibration, and model verification and application. Meaningful and quantitative measures are needed to establish model performance, and to provide a basis for model intercomparisons and possible future setting of standards. Various quantitative measures are suggested. To encourage their use, it is recommended that providing a quantitative measure when comparing model data with observed data be a condition for publication. A number of research needs are also identified.

Program ROUTWEIR represents a twodimensional flood routing model designed to analyze twodimensional flow caused by rainfall and runoff flooding events. Input to the program consists of known geometry, topography, initial conditions, and boundary conditions. The geometry and bathymetry of the flood plain are represented by a grid of interconnecting triangular elements. Initial water levels are prescribed to correspond to the normal water elevations in the river channel. Boundary conditions are prescribed by a discharge hydrograph at the upstream boundary of the river basin, and by the water surface elevations at the ocean boundary. The interior water elevations and discharges are computed, allowing flooding and drying to take place in the triangular elements of the grid, based on a conservation of water volume equation and a surface slope dependent dynamic equation. Output consists of time histories of water surface elevations and peak elevations in both tabular and graphical form. ROUTWEIR has been successfully calibrated against recorded flood levels in the Rio Culebrinas Basin in Puerto Rico and has been used in that basin in a federal flood insurance study. A versatile computer program, ROUTWEIR can be applied to many flood routing problems. It is particularly suited for wide river basins with large bottom slopes and for normally dry areas subject to extensive flooding.

Program ROUTWEIR represents a two‐dimensional flood routing model designed to analyze two‐dimensional flow caused by rainfall and runoff flooding events. Input to the program consists of known geometry, topography, initial conditions, and boundary conditions. The geometry and bathymetry of the flood plain are represented by a grid of interconnecting triangular elements. Initial water levels are prescribed to correspond to the normal water elevations in the river channel. Boundary conditions are prescribed by a discharge hydrograph at the upstream boundary of the river basin, and by the water surface elevations at the ocean boundary. The interior water elevations and discharges are computed, allowing flooding and drying to take place in the triangular elements of the grid, based on a conservation of water volume equation and a surface slope dependent dynamic equation. Output consists of time histories of water surface elevations and peak elevations in both tabular and graphical form. ROUTWEIR has been successfully calibrated against recorded flood levels in the Rio Culebrinas Basin in Puerto Rico and has been used in that basin in a federal flood insurance study. A versatile computer program, ROUTWEIR can be applied to many flood routing problems. It is particularly suited for wide river basins with large bottom slopes and for normally dry areas subject to extensive flooding.