A RATING-CURVE METHOD FOR HYDRODYNAMIC SIMULATIONS IN CONTAMINANT TRANSPORT MODELING

Accurate prediction of hydrodynamics is of great importance to modelin g contaminant transport and water quality in a river. Flow conditions are needed in estimating potential exposure contamination levels and t he recovery time for a no-action alternative in contaminated sediments remediation. Considering highly meandering characteristics of the Buf falo River, New York, a three-dimensional hydrodynamic model was selec ted to route upstream flows through the 8-km river section with limite d existing information based on the model's fully predictive capabilit y and process-oriented feature. The model was employed to simulate cha nges in water depth and flow velocity with space and time in response to variation in flow rate and/or water surface elevation at boundaries for given bottom morphometry and initial conditions. Flow conditions of the river reach where historical flow data are not available were c omputed. A rating-curve approach was developed to meet continuous and event contaminant modeling needs. Rating curves (depth-discharge and v elocity-discharge relationships) were constructed at selected stations from the 3-D hydrodynamic simulations of individual flow events. The curves were obtained as steady solutions to an unsteady problem. The r ating-curve approach serves to link flow information provided by the h ydrodynamic model to a contaminant transport model. With the approach, the linking problem resulting from incompatible model dimensions and grid sizes can be solved. The curves will be used to simulate sediment movement and to predict contaminant fate and transport in the river.